12/22/16 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

Preliminary Aquatic Risk Assessment to Support the Registration Review of Imidacloprid

NH Cl CH2 N 3l N Imidacloprid N

- + O N O December 22, 2016

PC Code: 129099. IUPAC Name: N-{1-[(6-Chloro-3-pyridyl)methyl]-4,5-dihydroimidazol-2-yl}nitramide

Prepared by: United States Environmental Protection Agency Keith G. Sappington, M.S, Senior Science Advisor Office of Pesticide Programs Mohammed A. Ruhman, Ph.D., Senior Agronomist Environmental Fate and Effects Division Justin Housenger, M.S., Risk Assessment Process Leader Environmental Risk Branch V 1200 Pennsylvania Ave. Approved by Mail Code 7507P Mah T. Shamim, Ph.D. Branch Chief Washington, D.C. 20460

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Contents 1. EXECUTIVE SUMMARY ...... 7 Background and Scope ...... 7 Assessment Approach ...... 7 Assessment Findings ...... 8 2. PROBLEM FORMULATION ...... 11 2.1. Nature of Regulatory Action and Assessment Scope ...... 11 2.2. Nature of the Chemical Stressor ...... 11 2.2.1. Overview of Pesticide Usage ...... 12 2.2.2. Pesticide Type, Class, and Mode of Action ...... 12 2.2.3. Overview of Physicochemical, Fate, and Transport Properties ...... 13 2.3. Ecological Receptors ...... 13 2.4. Ecosystems at Risk ...... 14 2.5. Assessment Endpoints ...... 14 2.6. Conceptual Models ...... 14 2.6.1. Diagram ...... 15 2.6.2. Risk Hypothesis ...... 16 2.7. Analysis Plan...... 16 2.7.1. Methods of Conducting Ecological Risk Assessment ...... 16 2.7.2. Measures of Exposure ...... 17 2.7.3. Measures of Effect ...... 17 2.7.4. Stressors of Toxicological Concern...... 18 3. EXPOSURE ASSESSMENT ...... 19 3.1. Use characterization ...... 19 3.1.1. Imidacloprid Labelled Use ...... 19 3.1.2. Imidacloprid Usage ...... 21 3.2. Environmental Fate and Transport Characterization ...... 27 3.3. Transformation Products/Degradates ...... 31 3.3.1. Persistence ...... 31 3.3.2. Degradation Profile ...... 32 3.3.3. Mobility ...... 33 3.4. Aquatic Exposure Modeling ...... 34 3.4.1. Inputs/Models ...... 34 3.4.2. Outputs ...... 40 3.5. Aquatic Exposure Monitoring ...... 48

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3.5.1. Surface Water Monitoring Data ...... 48 4. ECOLOGICAL EFFECTS CHARACTERIZATION ...... 66 4.1. Effects on Fish and Aquatic Phase Amphibians ...... 67 4.1.1. Acute Toxicity Studies ...... 67 4.1.2. Chronic Toxicity Studies ...... 68 4.2. Toxicity to Aquatic Invertebrates ...... 69 4.2.1. Acute Toxicity to Non-Insect Taxa ...... 70 4.2.2. Acute Toxicity to Insect Taxa...... 72 4.2.3. Acute Toxicity to Saltwater Aquatic Invertebrates ...... 76 4.2.4. Chronic Toxicity to Freshwater Aquatic Invertebrates ...... 77 4.2.5. Chronic Toxicity to Saltwater Aquatic Invertebrates ...... 81 4.3. Degradate Toxicity ...... 81 4.4. Reported Wildlife Incidents ...... 82 5. RISK CHARACTERIZATION ...... 85 5.1. Risk Estimation – Integration of Exposure and Effects Data ...... 85 5.1.1. Risks to Fish and Amphibians ...... 86 5.1.2. Risks to Aquatic Invertebrates ...... 86 5.2. Risk Description – Interpretation of Direct Effects ...... 99 5.2.1. Risks to Fish and Amphibians ...... 99 5.2.2. Risks to Aquatic Invertebrates ...... 100 5.2.3. Description of Assumptions, Sensitivity, Uncertainty and Data Gaps ...... 103 5.2.4. Endocrine Effects ...... 117 5.2.5. Threatened and Endangered Species Concerns ...... 118 6. RISK CONCLUSIONS ...... 119 6.1. Fish and Aquatic-phase Amphibians: ...... 119 6.2. Aquatic Invertebrates ...... 120 7. REFERENCES ...... 122 7.1. General References ...... 122 7.2. Registrant-submitted Environmental Fate Study Database ...... 126 7.3. Registrant-submitted Ecological Effects Study Database ...... 132 Appendix A: Labeled Use Patterns Tables...... 137 Appendix B. Example PWC Model Runs ...... 162 Appendix C. Relevant Ecotoxicity Data (Apical Endpoints) from EPA’s ECOTOX Database ...... 176 Appendix D: Additional Details on Modelling Approaches ...... 201

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Table of Tables

Table 1-1. Summary of Aquatic Invertebrate Acute and Chronic RQ Values for All Modeled Uses ...... 9 Table 2-1. Summary of Assessment and Measurement Endpoints for Imidacloprid ...... 18 Table 3-1. Summary of Registered Use Patterns and Associated Application Methods for the Agricultural Uses of Imidacloprid...... 20 Table 3-2. Name and Description of Non-Agricultural Usage Entries ...... 26 Table 3-3. Chemical Profile of Imidacloprid ...... 27 Table 3-4. Fate and Transport Properties for Imidacloprid ...... 28 Table 3-5. Chemical Input Parameters for Surface Water Modeling of Imidacloprid ...... 35 Table 3-6. Modeled Application Rates for Various Agricultural Use Patterns of Imidacloprid...... 36 Table 3-7. Modeled Application Rates for Various Non-Agricultural Use Patterns of Imidacloprid ...... 39 Table 3-8 Drift Fractions Associated with Varied Imidacloprid Application Procedures ...... 39 Table 3-9. EECs for Registered Foliar Use Patterns for Imidacloprid...... 41 Table 3-10. EECs for Registered Soil Use Patterns for Imidacloprid...... 42 Table 3-11. EECs for Registered Seed Treatment Use Patterns for Imidacloprid...... 43 Table 3-12. EECs for Registered Combined Application Method Use Patterns for Imidacloprid...... 44 Table 3-13. Summary Statistics for the USGS Nationwide Monitoring Data ...... 49 Table 3-14. Summary Statistics for CDPR Monitoring Data (Agricultural Waterbodies/Watersheds) ...... 54 Table 3-15. Summary Statistics for CDPR Monitoring Data (Northern and Southern CA Urban Waterbodies/Watersheds)1,2 ...... 55 Table 3-16 Summary Statistics for Surface Water Monitoring Data during Storms and Floods ...... 61 Table 3-17 Monitoring Data Summary for Two and Three Storm Events ...... 66 Table 4-1. Acute and Chronic Effects of Imidacloprid on Fish ...... 67 Table 4-2. Most Sensitive Acute Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid (and Selected Metabolites on Non-Insect, Freshwater Invertebrates ...... 71 Table 4-3. Most Sensitive Acute Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid (and Selected Metabolites) on Freshwater Dipteran Insects ...... 73 Table 4-4. Most Sensitive Acute Toxicity Values on the Effects of Imidacloprid on Ephemeropteran Insects (Mayflies) ...... 74 Table 4-5. Most Sensitive Acute Toxicity Values on the Effects of Imidacloprid on Other Aquatic Insect Taxa ...... 75 Table 4-6. Most Sensitive Acute Toxicity Values on the Effects of Imidacloprid on Saltwater Aquatic Invertebrates ...... 76 Table 4-7. Most Sensitive Chronic Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid on Non-Insect, Freshwater Invertebrates ...... 78 Table 4-8. Most Sensitive Chronic Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid (and One Metabolite) on Freshwater Insects ...... 79 Table 4-9. Summary of Chronic Toxicity Data on the Effects of Imidacloprid on Saltwater Aquatic Invertebrates ...... 81 Table 4-10. Summary of available acute degradate toxicity data to freshwater invertebrates...... 82 Table 4-11. Summary of reported aquatic wildlife incident reports ...... 84 Table 5-1. Risk Presumptions for Aquatic Animals ...... 86 Table 5-2. Maximum Acute and Chronic Risk Quotients for Freshwater and Saltwater Fish ...... 86 Table 5-3. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Soil Use Patterns of Imidacloprid ...... 87

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Table 5-4. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Foliar Use Patterns of Imidacloprid ...... 91 Table 5-5. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Seed Treatment Use Patterns of Imidacloprid ...... 93 Table 5-6. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Use Patterns Where Combined Application Methods of Imidacloprid Are Permitted ...... 95 Table 5-7. Summary of Aquatic Invertebrate Acute and Chronic RQ Values for All Modeled Uses ...... 101 Table 5-8. Summary of Recent Regulatory Assessments and Literature Reviews of Imidacloprid Higher Tier Aquatic Effects Studies ...... 115 Table 5-9. Comparison of Recent Regulatory and Non-Regulatory Aquatic Risk Assessments for Imidacloprid ...... 116

Table of Figures

Figure 2-1. Conceptual Diagram Foliar, Soil, or Seed Treatment Applications of Imidacloprid ...... 15 Figure 3-1 Estimated Imidacloprid Average Annual Crop Usage (lbs. a.i) from 2004 to 2013 ...... 21 Figure 3-2. Imidacloprid Estimated Annual Usage in lbs a.i by Crop/Crop Group...... 22 Figure 3-3 USGS Usage Estimates for Imidacloprid by Year and Crop ...... 23 Figure 3-4. USGS Spatial Distribution of Imidacloprid Usage in lbs. a.i/sq. mile (Preliminary E-Pest-High) ...... 24 Figure 3-5. Usage of Imidacloprid in Agricultural and Non-Agricultural Sites in California (Years 2000 and 2006 to 2012) ...... 25 Figure 3-6. Imidacloprid Agricultural Usage by Crop in 2014 ...... 26 Figure 3-7. Imidacloprid Usage, by Non-crop, in 2014 ...... 27 Figure 3-8. Expected Degradation Profile for Imidacloprid in Various Compartments of the Environment ...... 33 Figure 3-9. USGS Monitoring Data for Streams, Rivers and Lakes Compared to Usage Data for the Same Years...... 51 Figure 3-10. Spatial Distribution of the National Monitoring Data (With Detects & Non-Detects; 2014 Crop Layer on the Background) ...... 52 Figure 3-11. Detected Concentrations of Imidacloprid in Sope Creek and Chattahoochee River, GA (4- Oct-2011 to Apr-4-2012)...... 53 Figure 3-12 Spatial Distribution of California Monitoring Data (panel A = Detects, panel B = Non-detects) ...... 56 Figure 3-13. Monitored Concentrations in Ditches, Creeks and Sloughs Compared to Concentrations in Rivers and Lakes ...... 57 Figure 3-14 Imidacloprid Usage in Agriculture and Observed Concentrations in Santa Barbra County, California from 2010 to 2013...... 58 Figure 3-15. Imidacloprid Usage and Observed Concentrations in the Urban Areas of Placer, CA from 2011 to 2015 (Empty Brown Circles Represent lbs a.i. Used in Non-Agricultural Areas)...... 59 Figure 3-16. Mixed Urban and Agricultural usage and observed concentrations of imidacloprid in Imperial County, CA during 2010 to 2015...... 60 Figure 3-17 Spatial Distribution of Storm Water Monitoring Sites ...... 62 Figure 3-18. Chemo-graphs of Imidacloprid Concentrations in Storm Waters from Four Sites in AL and NC...... 63 Figure 3-19 (continued) Chemo-graphs of Imidacloprid Concentrations in Storm Waters from Four Sites in NY and MA...... 64

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Figure 3-20 Monitored Concentrations of Imidacloprid in Storm Waters Carried by Five Streams Entering Suisun Marsh in California...... 65 Figure 4-1. Acute Toxicity of Imidacloprid to Freshwater Invertebrates (most sensitive value for each species; open symbols = open literature; solid symbols = registrant data; solid arrow = endpoint used for risk estimation)...... 72 Figure 4-2. Acute Toxicity of Imidacloprid to Mayflies as a Function of Endpoint (EC50, LC50) and Season (Source: Van den Brink et al., 2016) ...... 75 Figure 4-3. Most Sensitive Chronic Toxicity Values on the Effects of Imidacloprid on Freshwater Invertebrates (most sensitive value for each species; open symbols = open lit., closed symbols = registrant data; solid arrow = endpoint used for risk estimation)...... 77 Figure 4-4. Chronic Toxicity of Imidacloprid to Two Species of Mayflies and Two Seasons (Source: Roessink et al., 2013; Van den Brink et al., 2016) ...... 81 Figure 5-1. Detected Imidacloprid Concentrations in Surface Water (USGS, CDPR) Relative to the Range of Modeled Peak EECs ...... 102 Figure 5-2. Detected Imidacloprid Concentrations in Surface Water (USGS, CDPR) Relative to Acute and Chronic Toxicity Endpoints for the Mayfly, C. dipterum and C. horaria, Respectively...... 103 Figure 5-3. Change in Modeled EECs as a Function of Seeding Depth Used in Modeling...... 106 Figure 5-4. Monitored Maximum Concentrations Frequency of Detection in 9 Midwestern Streams. ... 108 Figure 5-5. Observed Change in Mean Concentrations and Detection Frequencies of Imidacloprid in During the Planting Season of Corn in Drained Wetlands in Iowa ...... 109 Figure 5-6. Percentage of Imidacloprid Acute EECs That Exceed Taxon-Specific Acute Toxicity Values for Freshwater Invertebrates ...... 112 Figure 5-7. Percentage of Imidacloprid Chronic EECs That Exceed Taxon-Specific Chronic Toxicity Values for Freshwater Invertebrates ...... 112 Figure 5-8. Exceedance Frequency of Imidacloprid in USGS Surface Water Monitoring Samples Relative to Chronic Toxicity Endpoints for Freshwater Invertebrates (non-detects assumed = 0) ...... 113 Figure 6-1. Acute and Chronic Risk Quotients for Freshwater Invertebrates Associated with Various Application Methods ...... 120

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1. EXECUTIVE SUMMARY Background and Scope

Imidacloprid, along with the other nitroguanidine-substituted neonicotinoid insecticides (clothianidin, thiamethoxam, and dinotefuran) are currently undergoing Registration Review by the USEPA. With imidacloprid, the EPA published a final registration review Work Plan in 2009 and issued a Generic Data Call-in in 2010 to obtain data required for assessing risks to bees and other taxa. Earlier in 2016, a Preliminary Pollinator Assessment was published for imidacloprid which examined the risks associated with agricultural uses to bees (USEPA 2016). This 2017 Preliminary Aquatic Risk Assessment evaluates risks to aquatic organisms from both agricultural and non-agriculture uses of imidacloprid. The focus of this assessment is on aquatic organisms since multiple regulatory and non-regulatory assessments have shown that aquatic organisms may be exposed to imidacloprid and aquatic invertebrates in particular are highly sensitive to imidacloprid exposure. Furthermore, a substantial body of aquatic monitoring and toxicity data have been generated for imidacloprid since the Agency’s last comprehensive risk assessment was conducted. In contrast, very little new data have been generated on the toxicity of imidacloprid to birds and mammals since the Agency’s most recent ecological risk assessments. The Agency therefore will rely on its previously conducted assessments for characterizing the risk of imidacloprid to non-insect terrestrial organisms. For its final ecological risk assessment, the Agency will fully evaluate risks to birds, mammals, and terrestrial plants.

Imidacloprid has been registered for use in the United States since 1994. Currently, imidacloprid is registered on a wide variety of agricultural crops covering most major crop groups in addition to numerous non-agricultural uses. Imidacloprid is a systemic, neonicotinoid insecticide which acts on the insect nicotinic acetylcholine receptors (nAChRs) of the nervous system via competitive modulation. The chemical properties of imidacloprid indicate it is readily soluble in water and that volatilization and bioaccumulation in aquatic organisms are negligible. Imidacloprid is considered persistent in terrestrial and aquatic environments with the exception of conditions that favor aqueous photolysis. The major routes transporting imidacloprid from treatment sites to aquatic habitats include runoff and spray drift.

Assessment Approach

A wide variety of agricultural and non-agricultural uses of imidacloprid were modeled in this risk assessment. Agricultural uses were grouped by the type of application method (soil, foliar spray, seed treatment and combinations thereof) whereas a subset of representative non-agriculture uses were modeled. All uses were modeled using the maximum single and annual application rates specified on the labels. Within each crop group and type of application method, estimated environmental concentrations (EECs) were calculated using standard exposure models. For risk assessment purposes, the highest and lowest EEC among all EECs within a crop group and unique application method were compared to acute and chronic toxicity endpoints to generate acute and chronic risk quotients (RQs). Aquatic toxicity data were obtained and reviewed from both registrant-submitted and open literature sources. The available toxicity data indicates that aquatic insects (and mayflies in particular) are among the most sensitive taxonomic groups tested to date with imidacloprid. Information on aquatic incidents and monitoring data were also considered as additional lines of evidence for characterizing risk.

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Assessment Findings

Fish and Aquatic-phase Amphibians (all application methods): No direct risk to fish or aquatic phase amphibians is indicated from any of the agricultural or non-agricultural uses assessed since all acute and chronic RQs were below their respective LOCs. The limited number of aquatic incidents reported for imidacloprid did not indicate direct adverse impacts on fish. Furthermore, available monitoring data indicate detected concentrations of imidacloprid are several orders of magnitude below levels shown to cause adverse effects in fish and aquatic-phase amphibians. While the risk of direct effects of imidacloprid to fish and amphibians is considered low, the potential exists for indirect risks to fish and aquatic-phase amphibians through reduction in their invertebrate prey base.

Aquatic Invertebrates (Foliar Spray and Combination Application Methods): The greatest potential risks identified for aquatic invertebrates pertained to uses with foliar and combination application methods (Table 1-1). Specifically, all modeled uses associated with foliar spray and combination application methods showed the potential for acute and chronic risks to listed and non-listed freshwater invertebrates (for both methods, acute RQ values ranged from 1.6 to 44 while chronic RQs ranged from 39 to 2130). Chronic risks were also identified for saltwater invertebrates from all foliar spray and combination application method scenarios modeled. With foliar applications, acute risks were not identified for non-listed saltwater invertebrates but risks were identified for listed saltwater invertebrates.

Aquatic Invertebrates (Soil Application Methods): Acute and chronic risks to freshwater invertebrates were identified for both agricultural and non-agricultural soil application uses (Table 1-1). Acute RQ values ranged from <0.01 to 15 and exceeded the acute risk to non-listed species LOC of 0.5 for over half of the agricultural and non-agricultural use scenarios modeled. Acute risks to listed freshwater invertebrate species were identified with 29 of the 31 agricultural use scenarios modeled (94%) and 8 of the 11 non-agricultural use scenarios modeled (73%). Soil applications made at depths > 2 cm resulted in no acute or chronic risks to aquatic invertebrates (coffee-soil injected; cucurbits-10 cm drench; poplar and Christmas trees-shanked in 20 cm). In addition, the commercial perimeter treatment (California scenario) resulted in RQ values below all levels of concern for freshwater invertebrates but those for the Florida scenario exceeded acute and chronic LOCs. Since acute toxicity endpoints were higher for saltwater invertebrates, none of the acute RQ values for the agricultural or non-agricultural use scenarios modeled with soil applications exceeded the non-listed species LOC of 0.5, however, 39% and 18% of the acute RQ values exceeded the listed species LOC of 0.05 for agricultural and non-agricultural uses, respectively. The vast majority of use scenarios modeled with soil applications also indicated chronic risk concerns with freshwater and saltwater invertebrates (RQ range: <0.01 to 699).

Aquatic Invertebrates (Seed Treatment). The lowest overall aquatic risk profile among the application methods was indicated for application of imidacloprid-treated seeds, although risks were still identified with some use scenarios. Those uses with planting depths greater than 2 cm resulted in no runoff to aquatic ecosystems based on exposure modeling. This modeling does not take into account the potential contamination from deposition of abraded seed coat dust onto the treated field or adjacent areas and therefore, may underestimate aquatic exposure from the planting of treated seeds. Currently, EPA does not have standardized methods for quantitatively modeling dust off of abraded

8 coating from treated seeds. With respect to potential exposure via drift of abraded seed coat dust, the Agency is working with different stakeholders to identify best management practices and to promote technology-based solutions that reduce this potential route of exposure. For freshwater invertebrates, acute RQ values range from <0.01 to 1.6 while chronic RQ values ranged from <0.01 to 84. No acute risks were identified for listed or non-listed saltwater invertebrates. Chronic risks were identified for saltwater invertebrates with 3 of the 8 (38%) scenarios modeled (RQ range: <0.01 to 5.1).

Table 1-1. Summary of Aquatic Invertebrate Acute and Chronic RQ Values for All Modeled Uses Acute RQ 1 Chronic RQ 1 Appl. Method Use Type (n) RQ Statistic FW SW RQ Statistic FW SW Agricultural Soil (31) min <0.01 <0.01 min <0.01 <0.01 max 15 0.35 max 699 43 RQ>0.5 61% 0% RQ>1 94% 81% RQ>0.05 94% 39% Non-Ag. Soil (11) min <0.01 <0.01 min <0.01 <0.01 max 4.5 0.10 max 226 14 RQ>0.5 55% 0% RQ>1 73% 64% RQ>0.05 73% 18% Agricultural Foliar (15) min 1.6 0.04 min 82 5.0 max 20 0.47 max 988 61 RQ>0.5 100% 0% RQ>1 100% 100% RQ>0.05 100% 60% Non-Ag. Foliar (9) min 1.7 0.04 min 95 5.9 max 20 0.47 max 1020 63 RQ>0.5 100% 0% RQ>1 100% 100% RQ>0.05 100% 89% Agricultural Seed (8) min <0.01 <0.01 min <0.01 <0.01 max 1.6 0.04 max 84 5.1 RQ>0.5 38% 0% RQ>1 50% 38% RQ>0.05 50% 0% Agricultural Combined (48) min 0.66 0.02 min 39 2.4 max 44 1.0 max 2130 131 RQ>0.5 100% 2% RQ>1 100% 100% RQ>0.05 100% 69% 1. RQ values in bold exceed the acute, non-listed or listed species LOC values (0.5 or 0.05, respectively) or the chronic LOC of 1.0

Other Lines of Evidence. Surface water monitoring data with imidacloprid were available from over 7,000 samples spanning approximately 15 years. Nationwide monitoring by the U.S. Geological Survey revealed frequencies of detection from 5% (rivers and lakes) to 13% in streams. High detection frequencies were identified for estuaries (67%) and drainage canals (61%) but these values are uncertain due to the low number of samples available for these systems. It is evident, however, that concentrations of imidacloprid detected in streams, rivers, lakes and drainage canals routinely exceed acute and chronic toxicity endpoints derived for freshwater invertebrates. Maximum values reported exceed the freshwater chronic toxicity endpoint by two orders of magnitude and the acute toxicity 9 endpoint by one order of magnitude. Only one aquatic incident was identified that involved a registered use of imidacloprid to turf. This incident involved mortality of crayfish along a stream following a runoff event after application to turf. Fish were not reported to be impacted in the stream. Lastly, the risk findings summarized in this assessment are in general agreement with recent findings published by Canada’s Pest Management Regulatory Agency and the European Food Safety Authority.

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2. PROBLEM FORMULATION

Problem formulation serves as the first step of a risk assessment and it provides the foundation for the entire ecological risk assessment. In addition to identifying the risk assessment scope and objectives, the problem formulation includes three major components: (1) assessment and measurement endpoints that reflect management goals and the ecosystem they represent, (2) conceptual models that describe key relationships between a stressor (i.e., pesticide) and assessment endpoint or between several stressors and assessment endpoints, and (3) an analysis plan that summarizes the key sources of data and methods to be used in the risk assessment (USEPA 1998).

2.1. Nature of Regulatory Action and Assessment Scope

As articulated by the Agency’s Registration Review Schedule, the nitroguanidine-substituted neonicotinoid insecticides (imidacloprid, clothianidin, thiamethoxam, dinotefuran) are currently undergoing Registration Review. With imidacloprid, the first installment of the Registration Review process was the publication of the Problem Formulation and Preliminary Work Plan documents in 2008, (USEPA 2008a; 2008b). With respect to assessing ecological risk, these documents summarized the available data on ecological effects and environmental fate of imidacloprid, identified key data gaps, and set forth a schedule for obtaining these data and completing the ecological risk assessment. Following its receipt and response to public comment comments, the Agency published a Final Work Plan in 2009 (USEPA 2009), which was subsequently amended in 2010 to request additional data related to assessing risks to bees (USEPA 2010a). Also in 2010, a Generic Data Call-In (GDCI) was issued (USEPA 2010b) that required registrants to submit certain types of environmental fate and effects data in preparation for the forthcoming Preliminary Ecological Risk Assessment document.

2.2. Nature of the Chemical Stressor

While the Agency’s Preliminary Ecological Risk Assessment typically focus on multiple taxa of aquatic and terrestrial non-target organisms, this preliminary assessment focuses solely on the risk of registered agricultural and non-agricultural imidacloprid uses to aquatic organisms, specifically fish and invertebrates. Aquatic plants will not be assessed as available data for vascular and non-vascular aquatic plants indicate toxicity endpoints that are several orders of magnitude above the highest estimated environmental concentrations (EECs) in surface waters. The rationale for focusing this risk assessment on aquatic animals is as follows:

 The environmental fate properties of imidacloprid suggest high mobility and solubility and therefore the likelihood to reach aquatic systems via runoff and spray drift events. Movement of imidacloprid to aquatic ecosystems has been confirmed by an extensive body of aquatic monitoring data summarized in this assessment.  Aquatic invertebrates, specifically aquatic insects, have been shown to be among the most sensitive taxa to acute and chronic exposures of imidacloprid Anderson et al. (2015), EFSA (2015), BCS (2016); Morrissey et al. (2015), PMRA (2016), Pisa et al. (2015), and Smit et al.

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(2015). This finding is consistent with the high sensitivity of terrestrial insects (bees) reported in 1 the Agency’s recently published Preliminary Pollinator Risk Assessment for Imidacloprid0F  An extensive amount of new aquatic toxicity data has been generated for imidacloprid since the 2 Agency conducted its most recent ecological risk assessments.1F Many of these data represent previously untested taxa and therefore, there is need to update the Agency’s previous aquatic risk assessment with this new information.  In contrast, very little new data have been generated on the toxicity of imidacloprid to birds and 3 mammals since the Agency’s most recent ecological risk assessments.2F The Agency therefore will rely on its previously conducted assessments for characterizing the risk of imidacloprid to 4 non-insect terrestrial organisms3F For its final environmental risk assessment, the Agency will fully evaluate toxicity to birds, mammals, and terrestrial plants that includes consideration of registrant submitted and open literature data as well as employing the most current methodologies for assessing potential risks to these taxa from the agricultural and non- agricultural uses of imidacloprid.

2.2.1. Overview of Pesticide Usage

Imidacloprid is registered on a wide variety of agricultural crops, including (but not limited to): several vegetable groups (root, tuber, bulb, leafy, brassica, cucurbit, and fruiting), cereal grains, citrus fruit, pome fruit, stone fruit, berries, tree nuts, beans and other legumes, herbs, oilseed crops (e.g., canola, cotton) and other use patterns not associated with a crop group such as peanuts and tobacco. It has been registered for use in the United States since 1994. Maximum application rates vary by crop and method, but typically do not exceed 0.5 pounds of active ingredient per acre (lbs a.i/A; single application or per year). Imidacloprid may be applied to crops via a variety of methods including aerial and ground foliar sprays, soil drench, chemigation, soil injection, in-furrow sprays, and seed treatment. There are a wide variety of non-agricultural uses, some examples of which include tree trunk injection, forestry, pet spot-on treatments, turf, and applications to ornamentals. A detailed summary of registered agricultural and non-agricultural uses of imidacloprid to be included in this assessment is provided in Section 3.

2.2.2. Pesticide Type, Class, and Mode of Action

Imidacloprid (IUPAC name: N-[1-[(6-chloropyridin-3-yl)methyl]-4,5-dihydroimidazol-2-yl]nitramide) is a systemic, neonicotinoid insecticide which acts on the insect nicotinic acetylcholine receptors (nAChRs) of the nervous system via competitive modulation (IRAC 2016). Imidacloprid is in the N-nitroguanidine 5 group of neonicotinoids (IRAC subclass 4A) along with clothianidin, thiamethoxam and dinotefuran.4F Its

1 USEPA 2016. Preliminary Pollinator Assessment to Support the Registration Review of Imidacloprid. D429937, 01/04/16. 2 Assessment examples include: IR4 Petition for the Use of Imidacloprid on Shellfish Beds in Willapa Bay and Grays Harbor, State of Washington (D399685+, 03/2013); EFED Section 3 and IR$ Risk Assessment for Imidacloprid for Use on Soybeans, Peanuts, Kava, Millet, Oats, Artichoke, Wild Raspberry, and Caneberry Subgroup (D344030+, 05/2007); and EFED Section 3 Risk Assessment for Imidacloprid to be used as a Seed and Spray Treatment for Multiple Crop Uses (D311925+, 04/2006) 3 Ibid 4 Ibid 5 http://www.irac-online.org/ 12 mode of action on target insects (terrestrial and aquatic) involves out-competing the neurotransmitter, acetylcholine for available binding sites on the nAChRs (Zhang et al. 2008). At low concentrations, neonicotinoids cause excessive nervous stimulation and at high concentrations, insect paralysis and death will occur (Tomizawa and Casida 2005). Imidacloprid is a xylem and phloem-mobile systemic compound that is readily taken up by the roots of the plant and translocated throughout the plant via 6 the transpiration stream5F .

2.2.3. Overview of Physicochemical, Fate, and Transport Properties

As will be described in Section 3.2, imidacloprid is a highly water soluble chemical with low vapor pressure and Henry’s Law Constants. These properties suggest that the chemical will be readily soluble for movement with water and that it is unlikely to volatilize to a meaningful degree. Furthermore, the organic carbon: water partitioning coefficient (KOC) for imidacloprid is low which suggests imidacloprid is unlikely to bioaccumulate in living tissues. The major routes transporting imidacloprid from treatment sites to aquatic habitats include runoff and spray drift.

As will be discussed in Section 3.2, imidacloprid is considered persistent in terrestrial and aquatic environments with the exception of conditions that favor aqueous photolysis. The dominant transformation process for imidacloprid are photolysis (very fast in the presence of water) and aerobic soil degradation. However, aerobic soil transformation for imidacloprid is very slow (half- life values range from 200 days to more than a year) and therefore, it is expected to persist in the soil system. Photodegradation may occur on soil surfaces via soil application and on wet foliage in case of foliar application, although photolysis on dry soil appears to be slow. Several metabolites of imidacloprid may be formed in the terrestrial soil/plant system but as will be shown in Section 3.2, all are determined to be minor in aquatic systems (i.e. <10% of the applied residues). Imidacloprid is considered xylem 7 mobile, with dominant uptake routes following the transpiration stream6F . Details of imidacloprid fate and transformation pathways are provided in Section 3.2.

2.3. Ecological Receptors

The receptor is the biological entity that is exposed to the stressor (US EPA, 1998). As indicated previously, this assessment focuses on aquatic organisms, specifically fish and invertebrates. Accordingly, aquatic receptors potentially at risk include (but are not limited to): fish, amphibians, and invertebrates (e.g., aquatic insects, mollusks, crustaceans, and worms).

Consistent with the process described in the Overview Document (US EPA, 2004), this risk assessment uses the surrogate species approach in its evaluation of imidacloprid. Toxicological data generated from surrogate test species that are intended to be representative of broad taxonomic groups are used to extrapolate to potential effects on a variety of species (receptors) among these taxonomic groupings.

Acute and chronic toxicity data from studies submitted by pesticide registrants along with data from the

6 Sur, R. and Stork, A. (2003). Uptake, translocation, and metabolism of imidacloprid in plants. Bulletin of Insectology. 56 (1), 35 – 40. 7 Ibid 13 available open literature are used to evaluate potential direct effects of imidacloprid to the aquatic receptors identified in this section. As stated earlier in the Problem Formulation, this assessment will be restricted to characterizing the risk of imidacloprid to aquatic organisms. The open literature studies are identified through EPA’s ECOTOX database (http://cfpub.epa.gov/ecotox/), which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of imidacloprid on biotic communities due to loss of species that are sensitive to the chemical and changes in structure and functional characteristics of the affected communities.

It is noted that data from a wide variety of species, particularly for aquatic invertebrates, are available from both registrant- submitted and open literature sources. Specifically, relevant acute and chronic effects data for imidacloprid were evaluated for 28 species of freshwater invertebrates and 7 species of estuarine/marine invertebrates.

2.4. Ecosystems at Risk

The ecosystems at potential risk from imidacloprid are extensive in scope due to the wide geographic distribution of potential imidacloprid application sites. As the assessment is focused on aquatic risks, the potential risks associated with terrestrial ecosystems will not be further discussed in this assessment.

Aquatic ecosystems potentially at risk include water bodies adjacent to (or downstream from) the treatment area and might include: static water bodies such as ponds, lakes, and wetland areas, impounded water bodies such as reservoirs or flowing waterways such as streams and rivers. For uses in coastal areas, aquatic habitat also includes marine ecosystems, including estuaries and salt marshes.

2.5. Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by an ecological entity (species, community, or other entity) and its attribute or characteristics (US EPA, 1998). For imidacloprid, the ecological entities may include the following, which are again restricted to aquatic organisms only: freshwater fish and invertebrates and estuarine/marine fish and invertebrates. The attributes for each of these entities may include growth, reproduction, and survival and are discussed further in Section 2.7 (Analysis Plan).

2.6. Conceptual Models

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically significant concentrations. An exposure pathway is the means by which a pesticide moves in the environment from a source to an ecological receptor. For an ecological pathway to be complete, it must have a source, a release mechanism, an environmental transport medium, a point of exposure for ecological receptors, and a feasible route of exposure.

A conceptual model is used in this risk assessment to provide a written and visual description of the

14 predicted relationships between the stressor, potential routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model consists of two major components: risk hypotheses and a conceptual diagram (US EPA, 1998).

2.6.1. Diagram

Based on the preliminary iterative process of examining fate and effects data, the conceptual model or the risk hypothesis model for foliar spray, soil, and seed treatment application is shown in Figure 2-1. In establishing the diagram for the conceptual model, it was necessary to go through an iterative process to identify: (1) likely stressors/exposure pathways; and (2) organisms that are most relevant and applicable to this assessment. Primary exposure routes for aquatic organisms include spray drift and runoff of imidacloprid into nearby bodies of water. Once in the water, the primary exposure route to aquatic organisms is direct uptake across respiratory membranes.

As the terrestrial assessment will rely on previous identified risks, the associated exposure routes will not be further discussed. As such, the potential for inhalation risk, as well as ingestion of contaminated drinking water will also not be discussed. The potential for imidacloprid to bioaccumulate in living tissues is determined to be low based on its log KOW.

Figure 2-1. Conceptual Diagram Foliar, Soil, or Seed Treatment Applications of Imidacloprid

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2.6.2. Risk Hypothesis

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in assessment endpoints) and may be based on theory and logic, empirical data, mathematical models, or probability models (EPA 1998). The ensuing risk assessment will evaluate whether or not the specific risk hypotheses are supported. For foliar, soil, and seed treatment applications of imidacloprid, the following ecological risk hypothesis is being employed for this risk assessment:

Based on the environmental fate, specifically the high solubility and mobility of imidacloprid as well as its broad range of registered uses and application methods, there is a potential that aquatic organisms will be exposed when imidacloprid is used in accordance with the label. Consequently, considering the MOA and toxicity of imidacloprid, the registered uses have the potential to cause adverse effects upon the survival, growth, and reproduction of non-target aquatic organisms.

2.7. Analysis Plan

The analysis plan provides a rationale for selecting and omitting risk hypotheses in the risk assessment. As with any risk assessment process, the analysis plan also articulates data gaps, the methods used to evaluate existing and anticipated data, and the assumptions that will be made where data may be missing. The analysis plan also identifies the specific measures of exposure (e.g., estimated environmental concentrations; EECs) and effect (e.g., median lethal dose for 50% of the organisms tested; LD50) which will be used to develop risk estimates.

2.7.1. Methods of Conducting Ecological Risk Assessment

The primary method used to assess risk in this screening-level assessment is the risk quotient (RQ) and follows closely methods outlined in the EPA Overview Document (USEPA 2004). The RQ is the risk value for the screening-level assessment and is the result of comparing measures of exposure to measures of effect. A commonly used measure of exposure is the estimated exposure concentration (EEC) and commonly used measures of effect include toxicity values such as the median lethal dose to 50% of the organisms tested (LD50), medial lethal concentration to 50% of tested organisms (LC50), the no observed 8 adverse effect level (NOAEL)7F , and the no observed adverse effect concentration (NOAEC). The resulting ratio of the point estimate of exposure and the point estimate of toxicity, i.e., the RQ, is then compared to a specified level of concern (LOC), which represents a threshold for concern; if the RQ exceeds the LOC, risks concerns are triggered. Risk presumptions, along with the corresponding RQs, equations, and LOCs are summarized in Section 5. Generation of robust RQs is dependent on the quality of data from both fate and toxicological studies. The adequacy of the submitted data was evaluated relative to Agency guidelines.

One aquatic effects data gap was identified for chronic effects of imidacloprid on saltwater fish. In this case, an acute to chronic ratio will be used to estimate the chronic NOAEC for saltwater fish.

8 A NOAEL refers to a dose-based toxicity endpoint whereas a NOAEC refers to a concentration based endpoint. 16

2.7.2. Measures of Exposure

Measures of exposure are estimates for a receptor that can be determined by modeling or monitoring data. Measures of exposure for imidacloprid are obtained from both modeling effort and available monitoring data. Exposure models used for this assessment include the suite of standard exposure models commonly used in pesticide risk assessments (USEPA 2004).

Modeling of aquatic Estimated Environmental Concentrations (EECs) was executed using tier II pesticide water calculator (PWC version 1.52). Detailed information about this model and other water models 9 used by the Agency can be found in the US EPA website8F .

2.7.3. Measures of Effect

Measures of ecological effects are obtained from a suite of registrant-submitted guideline studies conducted with a limited number of surrogate species. The test species are not intended to be representative of the most sensitive species but rather were selected based on their ability to thrive under laboratory conditions. Measures of effect are based on deleterious changes in an organism as a result of chemical exposure. Functionally, measures of effect typically used in risk assessments include changes in survival, reproduction, or growth as determined from standard laboratory toxicity tests. The focus on these effects for quantitative risk assessment is due to their clear relationship to higher-order ecological systems such as populations, communities, and ecosystems. Monitoring data such as adverse effect incident reports may also be used to provide supporting lines of evidence for the risk characterization.

In addition, effects other than survival, reproduction, and growth may be considered, though rarely are they used quantitatively to estimate risks since, in many cases, the relationship between these effects and higher-order processes is tenuous at best. Commonly used laboratory-derived toxicity values include estimates of acute mortality (e.g., LD50, LC50) and estimates of effects due to longer term, chronic exposures (e.g., NOAEC, NOAEL). The latter can reflect changes seen in mortality, reproduction, or growth. In general, for a given assessment endpoint the lowest (i.e., most sensitive) relevant measure of effect is used in calculating the RQ.

Assessment endpoints and their respective measures of effect are listed in Table 2-1.

9 URL for water models: : https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/models-pesticide-risk- assessment 17

Table 2-1. Summary of Assessment and Measurement Endpoints for Imidacloprid Measures of Exposure Measures of Effect Assessment Endpoint 1. Survival and reproduction Peak EEC (acute), 21-d 1a. Most sensitive freshwater fish of individuals and & 60-d surface water acute LC50. communities of freshwater EEC (chronic)1 1b. Most sensitive freshwater fish fish2 and invertebrates. early life stage chronic NOAEC and LOAEC. 1c. Most sensitive freshwater invertebrate acute EC50/LC50. 1d. Most sensitive freshwater invertebrate chronic reproduction NOAEC and LOAEC. 2. Survival and reproduction Peak EEC (acute), 21-d 2a. Most sensitive estuarine/marine of individuals and & 60-d surface water fish acute LC50. communities of EEC (chronic)1 2b. Most sensitive estuarine/marine estuarine/marine fish and fish early life stage chronic NOAEC and invertebrates. LOAEC. 2c. Most sensitive estuarine/marine invertebrate acute EC50/LC50. 2d. Most sensitive estuarine/marine invertebrate chronic reproduction NOAEC and LOAEC. LD50 = Lethal dose to 50% of the test population; NOAEC = No-observed-adverse-effect level; LOAEC = Lowest- observed-adverse-effect level; LC50 = Lethal concentration to 50% of the test population; EC50 = Effect concentration to 50% of the test population. 1 Based on a 1-in-10-year return frequency. 2 In the absence of data, freshwater fish may be used as surrogates for aquatic-phase amphibians in accordance with EFED risk assessment guidance.

2.7.4. Stressors of Toxicological Concern

As will be discussed in Section 3.3, imidacloprid may degrade into various products through multiple pathways. Metabolites identified from aerobic soil metabolism studies include IMI-olefin, nitrosamine, guanidine, and 5-keto urea isomers. The formation rates of the degradates from this pathway do not exceed 2% of the applied residues and are therefore considered to be minor. Conversely, in the aqueous photolysis pathway, imidacloprid degradates to the guanidine and urea metabolites at rates up to 17 and 10% of the applied residues, respectively. Formation rates for guanidine also reach 12 and 21% for the aerobic and anaerobic aquatic metabolism pathways, respectively. As will be discussed in Section 4.3, available acute toxicity data for the guanidine and urea degradates indicate their toxicity is at least 3 orders of magnitude less than parent imidacloprid. Therefore, the stressor of concern for this assessment is determined to be parent imidacloprid alone.

10 It is noted that in its previous Preliminary Pollinator Assessment9F , the Agency identified parent imidacloprid as well as the degradates IMI-olefin and IMI-5-hydroxy as the stressor of concern.

10 USEPA (2016). Preliminary Pollinator Assessment to Support the Registration Review of Imidacloprid. 18

Available environmental fate data suggest these two degradates are primarily plant metabolites and do not form to a significant degree via other degradation pathways.

3. EXPOSURE ASSESSMENT

Exposure assessment for the registered uses of imidacloprid begins with a detailed characterization of its labeled uses and current data on its usage across all crops and application methods (Section 3.1). Information regarding the fate and transport of imidacloprid and its transformation products is also evaluated (Sections 3.2 & 3.3). The labeled uses combined with environmental fate parameters serve as key inputs to the aquatic exposure modeling (Section 3.4). In addition to modeled concentrations, available data on concentrations of imidacloprid measured in surface waters of the U.S. is also considered and evaluated (Section 3.5).

3.1. Use characterization

3.1.1. Imidacloprid Labelled Use

Imidacloprid has over four hundred Section 3 and Section 24(c) (Special Local Needs) registrations in the U.S. In addition, it has twenty registrations for technical grade active ingredient and twelve formulation intermediates. Typical end use products (TEPs) include the following formulations: granules; ready-to- use solutions; emulsifiable concentrates; flowable concentrates; water soluble packaging; pelleted/tableted products; water dispersible granules; wettable powders; impregnated materials; dust; solid soluble concentrates; and pressurized liquids. End use products are applied as: liquid spray or drench; broadcast or in-band granules; broadcast or in station baits; and as seed coating. Based on examination of most of the labels, TEP use patterns may be categorized into two main categories: agricultural and non-agricultural.

Agricultural use patterns include the following:

(a) Foliar use patterns where TEPs are diluted and applied directly to the crop foliage as liquid spray mainly by ground, air or airblast for tree crops;

(b) Soil use patterns where TEPs are either diluted and applied directly to the soil as liquid spray/drench, or applied as is directly into the soil (e.g., granules); and

(c) Seed treatment use patterns where TEPs are applied to the seeds in various procedures.

Additionally, for certain use patterns, imidacloprid can be applied to the same crop through various application methods within the same growing season. For example, imidacloprid can be applied to stone fruits via a soil application which is then followed by a foliar application so long as the maximum annual rate does not exceed 0.5 lbs a.i/A.

Appendix A contains a list of the crops belonging to designated crop groups and subgroups on various imidacloprid labels. Detailed information on agricultural use patterns was extracted from the labels and 19 is presented in summary tables in Appendix A, as follows: Tables A-2 to A-4 for foliar application; Tables A-5 to A-10 for soil application; Tables A-11 to A-13 and Figure A-1 for seed treatment.

Non-agricultural use patterns include the following:

(a) Turf & Ornamentals in Nurseries and Residential/Commercial Areas;

(b) Poplar/Cottonwood and Christmas Tree Plantations;

(c) Forestry;

(d) Bait & Pellets in farms/residential/commercial areas; and

(e) Controlling burrowing shrimp in commercial shellfish beds in Willapa Bay, WA.

Labels for non-agricultural use patterns contain application parameters, procedure, timing, intervals, restrictions, and other information. Tables A-14 to A-21 (Appendix A) contains a summary of these use patterns.

Table 3-1 summarizes the registered agricultural use patterns of imidacloprid and the associated application methods.

Table 3-1. Summary of Registered Use Patterns and Associated Application Methods for the Agricultural Uses of Imidacloprid. Crop Group Foliar Soil Seed Treatment 1 – Root and Tuber Vegetables X1 X X2 3 – Bulb Vegetables X X3 4 – Leafy Green Vegetables X4 X 5 – Brassica (Cole) Leafy Vegetables X X X5 6 – Legume Vegetables X X6 X 8 – Fruiting Vegetables X X 9 – Cucurbit Vegetables X 10 – Citrus Fruits X X 11 – Pome Fruits X X 12 – Stone Fruits X X 13 – Berries and Small Fruits X7 X8 14 – Tree Nuts X X 15 – Cereal Grains X 19 – Herbs and Spices X X X9 20 – Oilseed X10 X10 X 23/24 (Tropical and subtropical Fruit (edible and X X inedible peel, respectively) Globe artichoke (no crop group) X X Hops (no crop group) X X Coffee (no crop group) X X Peanuts (no crop group) X X X Tobacco (no crop group) X X 20

1Potato and tuberous and corm only (1C and 1D, respectively); 2Sugar beet, root vegetables, and potato only (1A, 1B, and 1C, respectively); 3Onion, leek, and scallion only; 4Leafy green vegetables only (4A) 5Broccoli and mustard only; 6Legumes vegetables except soybean only (6B); 7Caneberry, bushberry, grape and strawberry only (13A, 13B, 13-07D/F, and 13-07G, respectively); 8 Caneberry, bushberry, grape, cranberry, and strawberry only (13A, 13B, 13-07D/F, 13-07G/H and 13-07G, respectively); 9Borage and mustard only; 10Cotton only

3.1.2. Imidacloprid Usage

Estimated national level usage data for imidacloprid were obtained from two sources: the Biological and 11 Economic Analysis Division of the Office of Chemical Safety and Pollution Prevention (BEAD/OCSPP) 10F and the pesticide usage maps of the United States Geological Survey (USGS) pesticide national synthesis 12 project11F . BEAD data were generated in support of the registration review of imidacloprid and cover average usage from 2004 to 2013 (Figure 3-1).

Right side of the graph: Seed treatment usage= 56% (labels in Red); Left side of the graph: Foliar and soil usage= 44% (labels in Green) Figure 3-1 Estimated Imidacloprid Average Annual Crop Usage (lbs. a.i) from 2004 to 2013

The average total annual crop usage of imidacloprid reported by BEAD was 1,116,000 pounds for the years 2004 to 2013 with 56% used for seed treatment and 44% used for other uses (foliar and soil applied). Soybean was the major seed treatment usage representing 36% of the total annual usage. Seed treatment for wheat, cotton, corn, potatoes and sorghum ranged from 1 to 9% of the total annual usage. Soil and foliar usage represented 44% of the total annual usage distributed in the range of 1 to 7% of the total annual usage between citrus, potatoes, grapes, cotton, leafy green vegetables, fruiting

11 BEAD 2015. Usage Report in Support of Registration Review Draft Risk Assessment Purposes for Imidacloprid; PC Code # 129099 (Claire Paisley-Jones Memo dated October 6, 2015). 12USGS website; URL: https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2014&map=IMIDACLOPRID&hilo=L

21 vegetables, soybeans, tree nuts, cucurbits, brassica vegetables, pome fruits, tobacco and others. Non- agricultural usage data for imidacloprid was not available.

Figure 3-2 summarizes the total annual lbs. (average lbs./year) usage distributed between various crops/crop groups and into seed treatment (SDT)/foliar and soil (CRP), when available. Usage on soybeans was the highest (430,000 lbs./year) followed by cotton, potatoes and wheat (100,000 each), citrus and grapes (78,000 and 60,000 lbs., each/year). Usage on leafy greens, fruiting vegetables, corn, tree nuts and others ranged from 27,000 to 42,000 lbs./year and on brassica, pome fruits, sorghum and tobacco ranged from 10,000 to 20,000 lbs/year.

Figure 3-2. Imidacloprid Estimated Annual Usage in lbs a.i by Crop/Crop Group.

It is noted that the BEAD data represent a screening level usage analysis (SLUA) estimated for agricultural crops in the United States. The SLUA does not include usage information on non-agricultural uses of imidacloprid (e.g. ornamental). Data are obtained from various sources, merged, averaged, and rounded so that the presented information is not proprietary, business confidential, or trade secret. Sources of the data include the United States Department of Agriculture's National Agricultural Statistics Service (USDA-NASS) for the years from 2004 to 2013; private pesticide market research for the years from 2004 to 2013; and California Department of Pesticide Regulation (CDPR) pesticide use reporting (PUR) database for the years from 2004 to 2012.

Based on average annual pounds of imidacloprid applied through the period from 2004 to 2013, usage increased on apples, carrots, cauliflower, cherries, cucumbers, grapefruit, grapes, lemons, oranges, pistachios, pomegranates, potatoes, walnuts, watermelons, and wheat (seed treatment), and usage on avocado was recorded for the first time. In contrast, imidacloprid usage decreased on corn (seed treatment), and peppers, while usage on apricots and eggplant dropped off completely. The largest increase in usage was observed in soybeans seed treatment usage, which increased from 300,000 to 400,000 lbs. a.i average applied annually. Usage in terms of pounds a.i. applied remained constant on

22 the remaining crops. Increases in usage measured in average and maximum percent crop treated (PCT) were also seen for many crops. Almonds, artichokes, broccoli, cabbage, cantaloupe, carrots, cauliflower, cherries, com (seed treatment), cucumbers, grapefruit, grapes, lemon, lettuce, onions, oranges, pistachios, plums/prunes, soybeans (conventional and seed treatment), spinach, squash, sugar beets (seed treatment), tomatoes, walnuts, and wheat (seed treatment) all show increased usage, in terms of PCT. On average, these crops showed five percent increases in average PCT. The largest maximum PCT increase was observed in artichokes, which increased from a maximum of 20 PCT to 60 PCT.

More detailed national usage data were also reported by the USGS in the form of estimates in pounds per year and per crop (Figure 3-3) and as spatial distribution in lbs a.i/sq. mile (Figure 3-4).

13 Figure 3-3 USGS Usage Estimates for Imidacloprid by Year and Crop12F

13 Graph obtained from URL: https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2014&map=IMIDACLOPRID&hilo=L

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Figure 3-4. USGS Spatial Distribution of Imidacloprid Usage in lbs. a.i/sq. mile (Preliminary E-Pest- 14 High)13F

As shown in Figure 3-3, imidacloprid annual usage steadily, but gradually, increased from nearly ¼ to ½ million pounds during the period spanning from the year 2000 up to and including 2006. In the years 2007, 2008 and 2009, usage increased to nearly ¾ million pounds. In the year 2010 up to and including the year 2014 usage sharply increased to >1.5 to nearly 2 million pounds. Additionally, major usage in the period from 2010 to 2014 was on soybeans followed by vegetables & fruits, orchards & crapes, cotton and wheat. Spatial distribution of imidacloprid usage shows a substantial increase in distribution of usage from the year 2000 to 2014 reflecting the increase in usage in areas of the country where soybeans, wheat, vegetables and cotton are planted. Data on crop usage show that the chemical is used throughout the country especially if non-agricultural usage in urban areas is included.

15 It is noted that California pesticide use reporting (PUR)14F data are the most detailed available as they include all the agricultural and most of the non-agricultural usage. Data are available for each county of the state and include the following entries: usage date (year/month/day), Site name (crop or non-crop name), Product name and % of a.i, usage in pounds of product and in pounds of a.i, acres treated and the application method (ground or aerial).

14 Maps obtained from URL: https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2014&map=IMIDACLOPRID&hilo=L 15 CDPR; PUR datasets URL: California Pesticide Information Portal ftp://pestreg.cdpr.ca.gov/pub/outgoing/pur_archives 24

The total pounds of a.i usage of imidacloprid throughout the years from the year 2000 to 2014 is shown in Figure 3-4.

Based on the most recent agricultural crop usage (from 2014), three categories of agricultural crop usage may be recognized: low usage period (~0.1 million lbs.) in the year 2000 up to and including 2008), medium usage period (~0.2 to 0.25 million lbs.) in the years 2009 up to and including 2012) and high usage period (~0.3 million lbs.) in the years 2013 and 2014 (Figure 3-5). The level of increase in agricultural crop usage in California appears to match that shown earlier for the National crop usage (USGS data) in the years from 2000 to 2012 however that level was lower (two-fold increase in California compared to three-fold increase nationally).

Figure 3-5. Usage of Imidacloprid in Agricultural and Non-Agricultural Sites in California (Years 2000 16 and 2006 to 2012)15F

California crop usage by crop for the year 2014 was graphed in Figure 3-6. Data show that imidacloprid major usage was on grapes (32% of the total) followed by fruiting vegetables and citrus (15-16%); brassica and leafy green vegetables (9%); and tree nuts (6%). Relatively low use was reported for cucurbits, cotton and strawberries (2-3%). The total for all other usage was 6% including usage on artichoke, bulb vegetables, Bush/Cane berries, herbs & spices, leafy petioles, legumes, peanuts oats, sweet potato watercress, pome fruits, pomegranate, potato, rooting vegetables, stone fruits, sugar beet, sunflower and tropical fruits. In contrast, the major national usage for the same year was on soybeans, cotton, potatoes and wheat followed by citrus and grapes.

16 *Note: The value for 2007 was adjusted on the assumption that the entry of 140,270 lbs. for "N-OUTDR TRANSPLANTS" is a possible error (Assume the entry= 1,402.70 lbs.). Entries for this item was <439 lbs. for all the other years (2000 and 2006 to 2012). 25

Figure 3-6. Imidacloprid Agricultural Usage by Crop in 2014

Non-agricultural usage data are available for California and usage varied through the years as it ranged from 26,000 to 92,000 lbs./year. California non-agricultural usage data include those reported by the professional pest control operators in entries summarized in Table 3-2. Homeowner usage is not reported.

Table 3-2. Name and Description of Non-Agricultural Usage Entries Entry Name Entry Description Structural Pest Control Any pest control work performed within or on buildings and other structures Landscape Maintenance Any pest control work performed on landscape plantings around residences or Pest Control other buildings, golf courses, parks, cemeteries, etc. Any pest control work performed along roadsides, power lines, median strips, Right-of-Way Pest Control ditch banks, and similar sites Any vertebrate pest control work performed by public agencies or work under the Vertebrate Pest Control supervision of the State or county agricultural commissioner Commodity Fumigation Fumigation of nonfood/non-feed commodities such as pallets, dunnage, furniture, (Nonfood/Non-feed) burlap bags, etc. Any pest control work performed by public employees or contractors in the Regulatory Pest Control control of regulated pests

Other entries considered as non-agricultural usage herein included: Christmas trees, forestry, turf and all nursery entries (N-GRNHS/N-OUTDR “flower/plants in containers”). N-OUTDR “transplants” is considered in this assessment as agricultural usage on the assumption that it is referred to transplants of crops such as tomatoes, peppers and others. Data for non-agricultural usage for the year 2014 are summarized in Figure 3-7. As shown in Figure 3-7, major non-agricultural usage for 2014 was on structural pest control (56%) followed by landscape maintenance (19%), animal husbandry and public health pest control (10% each) and nurseries (4%). Relatively low use (1% or less) was reported for others including: right of way/un-cultivated land, turf, forest trees and others.

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Figure 3-7. Imidacloprid Usage, by Non-crop, in 2014

3.2. Environmental Fate and Transport Characterization

Table 3-3 contains a summary of the chemical profile of imidacloprid. Available data indicate that imidacloprid is highly soluble with low vapor pressure and Henry’s Law Constants. These properties suggest that the chemical will be readily soluble and thus available for movement with water, and that it is unlikely to volatilize to a meaningful degree. Furthermore, the Kow for imidacloprid is low, and this property along with the high solubility are known attributes of systemic pesticides that can move upward in the plant within the xylem and phloem. Furthermore, the relatively high persistence of imidacloprid in the soil system and its predicted mobility are characteristics of pesticides that are expected to leach and may contaminate vulnerable ground water resources.

Table 3-3. Chemical Profile of Imidacloprid Property Value

NH Cl CH2 N 3l N Imidacloprid Chemical Structure: Name N - + O N O 1-(6-chloro-3-pyridin-3-ylmethyl)-N-nitroimidazolidin-2- ylidenamine CAS Number 138261-41-3 Molecular Formula C9H10ClN5O2 Molecular Weight (CAS No.) 255.7 g/mole (13826-41-3)

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Property Value Water Solubility @ 20 oC 580-610 mg/L (ppm) o Octanol: Water Coefficient Kow 3.7 @ 21 C Vapor pressure (Henry’s Law Constant) 1.5 x 10-9 torr (9.9 x 10-13 atm m3 mol-1) @ 20 oC

The environmental fate and transport characteristics of imidacloprid are summarized in Table 3-4. These data suggest that the compound is relatively stable to multiple routes of degradation other than photolysis in water, and to some extent biolysis in aerobic and anaerobic aquatic systems. Given the persistence of imidacloprid in soil and its mobility, the compound has the potential to leach to ground water and/or to be transported by runoff into surface water, a potential that may exist for extended periods of time depending on the soil permeability and climatic conditions.

Table 3-4. Fate and Transport Properties for Imidacloprid Property Values1 MRID2 Stable @ pH 5, 7 and hydrolyzed slowly (Extrapolated Hydrolysis t½ 420553-37 (A) t½= 355 d) in sterile alkaline solutions @ pH 9 0.2 days Major Metabolites: Guanidine or desnitro compound (NTN-333823): Max 17% and urea compound (NTN-33519): Max 10% @ End of study= EOS Additionally, three major unknowns reached Maximums of 8-13% after 2 Environmentally hrs. Relevant Direct Minor Metabolites: Several unknowns with a total Max of 13% after 2 hrs. Aqueous Important Notes: 422563-76 (A) Photolysis t½ (1) UV spectrum of the chemical has a maximum absorption at 269 nm, (Two-hour therefore degradation by sunlight is expected study) (2) Under natural sunlight, in a dilute aqueous solution in the greenhouse: 60% of the chemical degraded within 4 hours supporting the results of the study

171 days in a sandy loam soil from Kansas (pH= 5.2; O.C= 1.4% and CEC= 22 meq/100 g) Major Metabolites: None Environmentally Minor Metabolites: 5-hydroxy compound (WAK-4103): Max 6%; Relevant Soil Nitrosimine compound (WAK-3839): Max 1% and a mixture of urea 422563-77 (A) Photolysis t½ (15- compound (NTN-33519) and Olefin compound (NTN-35884): Max 3%; and d study) 6-Chloronictonic acid: Max 2%; All Maximums @ EOS. Additionally, two unidentified reached Maximums of >>5% after 15 days Un-extracted Residues (UER): Max 11% after 15 days 608 days (SFO*; Extrapolated value because parent reached only 62% @ EOS) in a sandy loam soil from Kansas (pH= 4.8; O.C= 1.4% and CEC= 16 meq/100 g). Aerobic soil t½ @ Note: Levels of metabolites were insufficient to permit their identification 20 oC (Needed 20x to 100x the rate) (End of study Major Metabolites: None “EOS” = 366 420735-01 (A) Minor Metabolites: M1= Olefin compound (NTN-35884); M2= WAK-4230-1; days; Pyridinyl- M3= Nitrosamine compound (WAK-3839); M4= Guanidine compound 14C-methylene (NTN-33823) and M5 & M6= Two isomers of 5-keto-urea compounds (Max imidacloprid) 0.2-2% each). Additionally, one unidentified compound reached maximums of nearly 1% @ EOS; (Max for Total Minor Metabolites= 6%) Un-extracted Residues (UER): Max 32% @ EOS reduced to 13% after

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Property Values1 MRID2 additional reflux extraction yielding parent (considered as bound parent as it was extracted with harsh extraction) Mineralization to CO2: Max 7.4% @ EOS 172 days (Slow DFOP; Extrapolated value because parent reached only 63% @ EOS) in BBA 2.2, a loamy sand soil from Germany (pH= 5.5; O.C= 2.2% and CEC= 10 meq/100 g). Aerobic soil t½ @ Note: Levels of metabolites were insufficient to permit their identification; 20 ± 2 oC Needed 20x to 100x the rate (End of study Major Metabolites: None “EOS” = 100 452393-01 (A) Minor Metabolites: M1; M2; M3; M5 & M6 (refer to the soil, above) plus days; Pyridinyl- M7= 6-chloronicotinic acid (Max= 2.2% each with a total Max of 4%) 14C-methylene Mineralization to CO2: Max 10% @ EOS imidacloprid) Un-extracted Residues (UER): Max 22% @ EOS reduced to 14% after additional reflux extraction yielding parent (considered as bound parent as it was extracted with harsh extraction) 193 days (SFO; Extrapolated value because parent reached only 67% @ EOS) in Hoefchen, a silt soil from Germany (pH= 5.3; O.C= 1.2% and CEC= 11 Aerobic soil t½ @ meq/100 g). 20 ± 2 oC Major Metabolites: None (End of study Minor Metabolites: Several metabolites occurred at very low levels (not “EOS” = 100 452393-02 (A) identified nor quantified) days; Pyridinyl- Mineralization to CO2: Max 6.4% @ EOS 14C-methylene Un-extracted Residues (UER): Max 22% @ EOS reduced to 13% after imidacloprid) additional reflux extraction yielding parent (considered as bound parent as it was extracted with harsh extraction) 336 days (SFO; Parent reached 52% @ EOS) in Monheim 1, a sandy loam Aerobic soil t½ soil from Germany (pH= 5.3; O.C= 1.2% and CEC= 11 meq/100 g). @ 22 ± 2 oC (End Major Metabolites: None of study “EOS” = 452393-03 Minor Metabolites: None were tracked, if any 366 days; Or 425329-03 Mineralization to CO2: Max 5% @ EOS Pyridinyl-14C- (A) Un-extracted Residues (UER): Max 40% @ EOS decreased to 18% after methylene additional reflux extraction yielding parent (considered as bound parent as it imidacloprid) was extracted with harsh extraction) 139 days (slow DFOP*; Parent reached 40% @ EOS) in Sarotti (silt loam, pH 7.0, O.C= 1.46% and CEC= 13 meq/100 g) soil from Germany 242 days (slow DFOP*; Parent reached 50% @ EOS) in Laacherhof (sandy loam, pH 6.2, O.C= 1.88% and CEC= 9 meq/100 g) soil from Germany Aerobic soil t½ 332 days (slow DFOP*; Parent reached 57% @ EOS) in Wurmwiese (sandy @ 20 ± 0.2 oC loam, pH 5.4, O.C= 1.69% and CEC= 10 meq/100 g) soil from Germany (End of study 177 days (slow DFOP*; Parent reached 38% @ EOS) in Hoefchen am 498358-02 “EOS” = 120 Hohenseh 4a (silt loam, pH 6.5, O.C= 2.59% and CEC= 14 meq/100 g) soil with days; Pyridinyl- from Germany 498358-03 (A) 14C-methylene Major Metabolites: None imidacloprid) Minor Metabolites: Multiple unknowns with Max ranging from 9.8 to 11.3% consisting of minor multi degradate residues. Attempts to identify residues was not successful (MRID 498358-03) Mineralization to CO2: Max 12-28% @ EOS Un-extracted Residues (UER): Max 15-21% @ EOS Anaerobic 33 days (SFO) in pond water sediment system from Stanly, Kansas (Water: 422563-78 Aquatic t½ Total organic carbon (TOC) 5 mg/L; Sediment: silt loam, pH 6.9, O.C= 3.15% (S) @ 22 ± 1 oC (End and CEC= 14 meq/100 g) soil from Germany

29

Property Values1 MRID2 of study “EOS” = 358 days; Major Metabolites: Guanidine= Max 21% @ 60 d declined to 16% @ EOS Pyridinyl-14C- Minor Metabolites: None methylene Mineralization to CO2: Max 0.2-0.5% @ 249 d to EOS imidacloprid) Un-extracted Residues (UER): Max 73% @ EOS Noting that harsh reflux boiling with acetone: 1 N HCl yielded high levels of Guanidine. Therefore, the authors suggested that the major part of the UER is Guanidine noting (without data) that parent could withstand the harsh extraction and that Guanidine is not an artificial product resulting from the effect of harsh extraction on parent. The possibility of parent artificially converting to Guanidine may not be ruled out without submittal of data supporting the claim that parent could withstand the harsh extraction. The 73% of radioactivity, above, contains radioactivity attributed to the UER (left after the harsh extraction) plus the radioactivity attributed, by the authors, to be Guanidine 32 days (SFO) in an orchard ditch water: loamy silt sediment system (Water: pH 8.4 and TOC= 5 mg/L; Sediment: OC%= 4.1%) from IJzendoorn, Netherlands

Major Metabolites: Guanidine= 12% @ EOS Minor Metabolites: 6-chloronictonic Acid= Max 1% @ 29 d declined to <1% @ EOS; and DIJ 9646-2= Max <1% throughout and un-characterized Aerobic Aquatic residues= Max 6% @ 29 d declining to 4% @ EOS t½ Mineralization to CO2: Max 1.4% @ EOS @ 22 oC (End of Un-extracted Residues (UER): Max 66% @ EOS study “EOS” = 92 484169-01 (S) days; Pyridinyl- 159 days (SFO) in a re-cultivated quarry water: loamy sand sediment system 14C-methylene (water: pH 8.1 and TOC= 4 mg/L; sediment: OC%= 0.9%) from Lienden, imidacloprid) Netherlands

Major Metabolites: None Minor Metabolites: Guanidine= Max 9% and 6-chloronictonic Acid= 4% @ EOS; and DIJ 9646-2= Max 2% @ EOS and un-characterized residues= Max 4% @ 60-EOS Mineralization to CO2: Max 2% @ EOS Un-extracted Residues (UER): Max 15% @ EOS >30 days (parent was 84% @ EOS) in a pond water: silty clay sediment Aerobic Aquatic system (water: pH 8.5 and TOC= 4 mg/L; sediment: pH 7.6 and OC%= 2.1%) t½ from Kansas, USA @ 22oC (End of study “EOS” = 30 Major Metabolites: None 484169-02 (S) days; Pyridinyl- Minor Metabolites: WAK 4103= Max 3% @ 7 d declined to 2% @ EOS; 14C-methylene Nitrosimine, Cyclic Urea & GBH 4315= 1% 14 d- EOS imidacloprid) Mineralization to CO2: Max 0.7% @ EOS Un-extracted Residues (UER): Max 8-10% 21 d-EOS 484169-03 Non-guideline study (In the natural environment light attenuation in deep (none- Aerobic Aquatic water bodies is expected to reduce the effects of aqueous photolysis) guideline study) Terrestrial Field All studies were Unacceptable. Studies were conducted on turf, bare 422563- Dissipation ground, Tomatoes and corn in the States of GA, MN, CA, GA and MN 9/80/81/82/83

30

Property Values1 MRID2 (U) Parent: Average= 266 (n=15) ranging from 98-487 in soils with varied Parent: texture, Clay= 1 to 43%, Organic carbon (O.C) = 0.23 to 3.95%, pH= 4.5 to 425208-01 7.8, and Cation exchange capacity (C.E.C) = 4 to 41 meq/100 g 420553-38 -1 Koc (L Kg ) and Guanidine Metabolite: Average= 742 (n=4) ranging from 327 to 942 in soils 476994-44 with varied texture (Sand, Loamy sand, Sandy loam and Loam, O.C= 0.23 to 1.51%, pH= 5.1 to 6.5, and C.E.C= 4 to 16 meq/100 g 425208-02 1 Values for half-lives were estimated as per NAFTA degradation kinetic: SFO model= Single Order; DFOP model= Double First Order; and IORE model= Indeterminate Order Rate Equation; 2 Study classification: A= Acceptable; S= Supplemental

3.3. Transformation Products/Degradates

3.3.1. Persistence

Fate data suggest that imidacloprid is persistent in terrestrial and aquatic environments with the exception of conditions that favor aqueous photolysis. It is noted however, that imidacloprid persistence in aerobic soil system is more than that expected in anaerobic/aerobic aquatic systems. Photo- degradation may occur on soil surfaces in the case of direct/indirect soil application and on foliage in case of foliar application. Photolysis on soil data suggest that dissipation of imidacloprid through this process is expected to be slow (t½ = 171 days). In contrast, aqueous photolysis is expected to be a significant process for imidacloprid transformation on wet foliage during daylight when the chemical is applied directly to foliage. The significance of this process is dependent on the presence of light and moisture (rain and/or irrigation) and on factors that determine how much of the chemical is present on foliage: application rate, formulation, tank mixes, timing, procedure and plant foliage density/characteristics) and for how long (affected by plant wash-off by rain and/or irrigation). Although many factors are required for dissipation of the chemical by aqueous photolysis, laboratory data suggest that abiotic photolysis may play an important role in imidacloprid dissipation (t½ = 0.2 days).

As will be shown later in this assessment, available field data do not show that the aqueous photolysis process is important from a dissipation standpoint. Aerobic and anaerobic aquatic transformation are expected to contribute to dissipation of imidacloprid reaching aquatic systems by run-off and drift. Metabolism appears to be more pronounced in anaerobic conditions (t½ = 33 days; n=1) compared to th aerobic conditions (upper 90 confidence limit on the mean t½ 236 days; n=2). Aerobic soil transformation of imidacloprid is expected to be relatively slow with degradation half-lives ranging from th 172 to 608 days and upper 90 confidence limit on the mean t½ of 254 days (n=8). Based on this route of degradation alone, imidacloprid is expected to be highly persistent in the soil system. This persistence in soils may lead to accumulation over the years with repeated applications. However, the magnitude of soil accumulation is expected to be highly affected by other important routs of dissipation including: leaching, run-off and plant up-take which are expected to reduce this accumulation.

For persistence of imidacloprid in the field, available terrestrial field dissipation studies are all classified as invalid for several reasons including application rates not confirmed, and metabolites were not

31 tracked. However, available rotational crop studies confirmed occurrence of soil carry-over from application to one crop to the following crop based on data obtained for magnitude of residues in rotational crops (MRIDs: 432459-01 and 440637-01). In these studies, detectable residues of imidacloprid were found in variable quantities in rotational crops planted after 1, 4, 8 and 11 months rotational intervals following a single granular application of 0.29-0.32 lb. a.i/A. Measured average residues of imidacloprid plus its metabolites (parent plus metabolites containing the 6-chloropyridinyl moiety) were observed in California: wheat forage/straw (0.12-0.19 (ppm), turnip tops (0.58 ppm), and spinach leaves (0.32 ppm) all planted-back after 8 months. It is noted however, that residues were much lower in other parts of the plant such as roots and grain (e.g., grains: <0.05 ppm) and that the magnitude of residues varies within a given crop depending on the planting location (i.e., CA vs. KS or MS).

3.3.2. Degradation Profile

The degradation pathways for imidacloprid in the environment are summarized in Figure 3-8. In the soil system, imidacloprid is expected to resist degradation producing only minor amounts of degradation products (maximum of 2%). Formed degradates include olefin, 5-keto-urea isomers, nitrosimine and guanidine. Formed degradates preserve the structure of their parent. Eventually, degradation products degrade into the 6-chloronicotinic acid and varied amounts CO2 (5-28%) and bound residues.

In aquatic systems, imidacloprid is expected to be affected by biotic metabolism which is more pronounced under anaerobic conditions than aerobic conditions. Guanidine is the major degradation products as it reached maximums of 9% of the applied under aerobic conditions and 21% of the applied under anaerobic conditions. Under aerobic aquatic conditions, three other degradates appear to form namely, 5-hydroxy (Max= 3%), the transitional degradate DIJ 9646-2 and the terminal degradate 6- chloronicotinic acid (Max= 4%). Mineralization to CO2 ranged from a maximum of 0.5% under anaerobic conditions to a maximum of 2% under aerobic conditions.

32

NH Cl CH2 N 3l N Guanidine NH Max= 12/21%

PARENT

NH Cl CH2 N 3l N Imidacloprid DIJ 9646-2 (Max 2% Aerobic only) N - + O N O 5-Hydroxy WAK-4103 (Max= 3%, aerobic only) Direct Photolysis t½ = 0.2 days 6-chloronicotinic acid (Max 4% Aerobic only) + Bound Residues

+ CO2= 2%/0.5%

NH NH2 Cl CH2 N Cl CH2 NH NH 3l 3l N N

Olefin WAK-4230-1 NO2 N NO2 N

O O

NH NH 5-Hydroxy WAK-4103 Cl CH2 N Cl CH2 N 3l 3l (Max= 6% in photolysis on soil only) N N

O 5 - Keto-Urea Isomers O

5-Keto – Urea Isomers

NH Cl CH2 N 3l N Nitrosimine N NO Max= 17% Maximum for each of the six Metabolites, above: 0.2-2%

NH Cl CH2 N 3l N Urea O Max= 10% 6-chloronicotinic acid (Max= 2%) + Bound Residues + CO2= 5-28%

Figure 3-8. Expected Degradation Profile for Imidacloprid in Various Compartments of the Environment

3.3.3. Mobility

Based on laboratory batch equilibrium studies, parent imidacloprid is expected to be moderately mobile -1 (Average Koc = 266 L Kg , n=125; FAO Classification). Persistence/mobility data suggest that imidacloprid has the potential to leach to groundwater and/or to move to surface waters in run-off and this potentially may exist for long periods of time. Leaching of imidacloprid was confirmed in the field by 33 two prospective ground water (PGW) studies. One of the studies was conducted in Montcalm County, Michigan (0.34 lbs. a.i/A to potatoes) and the other in Monterey County, California (0.45 lb. a.i/A to broccoli). In both studies, the registrant monitored for imidacloprid parent, imidacloprid guanidine, imidacloprid olefin, and imidacloprid urea in the vadose zone (area between ground surface and where groundwater is at atmospheric pressure) and in shallow ground water. In both studies, the predominant compound detected in soil, soil-pore water throughout the vadose zone, and in ground-water (when detectable) was parent imidacloprid. Of the three degradates analyzed for (guanidine, olefin, and urea compounds) only the urea compound leached at concentrations that were frequently detectable in the shallow ground water. It was noted that detections in ground water (i.e., breakthrough) started after 500 days from application and continued five years after application. Residues of imidacloprid in ground water were most frequently observed under use conditions which promoted greater ground-water recharge and/or when imidacloprid was used in multiple growing seasons at the same site.

3.4. Aquatic Exposure Modeling

Modeling for aquatic exposure EECs was conducted using tier II pesticide water calculator (PWC version 1.52). Detailed information about this model and other water models used by the Agency can be found 17 at the US EPA website16F .

3.4.1. Inputs/Models

Aquatic modeling requires inputs related to labeled uses, application parameters and the chemical, physical and fate and transport characteristics of imidacloprid. In addition, label restrictions should also be considered such as those related to drift reduction (i.e., buffer zones), pollinator protection (i.e., modification of the application window) and others.

For this ecological risk assessment, the Agency used modeling to estimate the range of aquatic exposure EECs (lowest and highest) expected from all of the current agricultural and no-agricultural use patterns. In this respect, it is noted that identifying the range of exposure for imidacloprid was difficult because of its extensive use patterns which were varied in the application procedures, rates, intervals, restrictions, combined applications, and in most cases application windows extending from planting to near harvesting. Varied modeling inputs were determined as shown below.

A. Chemical Input parameters

Required chemical parameters are summarized in Table 3-5. These parameters are based on the 18 physical, chemical, fate and transport properties of imidacloprid and are selected as per the guidance.17F

17 URL for water models: https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/models-pesticide-risk- assessment 18 The chemical parameters guidance is available at US EPA web; URL: https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/guidance-selecting-input-parameters-modeling

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Table 3-5. Chemical Input Parameters for Surface Water Modeling of Imidacloprid Parameter Value Reference Average for 15 soils (MRIDs 425208-01; 420553-38 and -1 266 Sorption Coefficient (Koc, L Kg ) 476994-44) The upper 90th confidence limit on the mean t½ from two Water Column Metabolism t ½ (day) o 236 @ 25 C values/systems (MRID 484169-01) One whole-system t½ of 27 days multiplied by 3= 81 days (MRID 422563- Benthic Metabolism t ½ (day) o 81 @ 25 C 78) Aqueous Photolysis t ½/Latitude (day/o) 0.2 @ 40 o MRID 422563-76 Hydrolysis t ½ (day) 0=Stable MRID 490111-21 The upper 90th confidence limit on the mean t½ from eight values for Aerobic Soil Metabolism t ½ (day) o 254 @ 25 C parent (MRIDs 420735-01; 452393-01/02/03; 498358-02) Foliar t ½ (day) Model default value Molecular Weight (g mole-1) 255.7

Vapor pressure (torr) 1.5 x 10-9 Solubility in Water mg L-1 610 Henry’s Law Constant (unitless) 3.38 x 10-11 Spray Drift (Efficiency) Varies (refer to Table 3-8 below) Cropped Area Fraction 1 (multiple crops)

B. Application Dates

Application dates for imidacloprid depend on the type of application, timing of pest pressure as related to the stage of plant growth and the systemic nature of this pesticide. In order to achieve optimum pest control, directed or broadcast foliar sprays of imidacloprid is recommended to be at the earliest threshold for target pests. Optimum pest control for soil applications is expected to result from application to the root zone of the plants at an early time so that is available for earlier protection to the developing plant. In determining application timing for soil application and foliar application, many factors were considered in selecting the application windows for imidacloprid use patterns. The factors were derived from label information on timing/length of application including: crop stage(s) at time of application; pre-harvest intervals; restrictions related pollinator protection; and the time needed to complete applications (if more than one application is permitted). For further information on the modeling approach related to application dates which includes examples used as case studies, refer to Appendix D.

C. Labelled Application Rates

Imidacloprid labeled use patterns may be categorized into two main categories: Agricultural and Non- agricultural. Agricultural use patterns include: foliar use patterns whereas the products are diluted and applied directly to the crop foliage as liquid sprays mainly by ground, air or airblast. In contrast, the products for the soil use patterns are either diluted and applied directly to the soil as liquid spray, drench or applied directly into the soil as is (e.g., granules). Finally, the products for the seed treatment

35 use patterns are applied as a seed coating in varied seed treatment procedures. Non-agricultural use patterns include: turf & ornamentals in nurseries and residential and commercial areas; poplar- cottonwood and Christmas tree plantations; forestry; bait & pellets in farms, residential, and commercial areas; and special uses such as the product used for controlling burrowing shrimp in commercial shellfish beds in Willapa Bay, WA.

Agricultural Use Patterns

Imidacloprid is registered for a wide range of agricultural use patterns, of which use information is summarized below in Table 3-6. In most cases, labels for imidacloprid permit combined applications of foliar, soil, and/or seed treatment. In order to conduct modelling for these uses, it had to be clarified with the registrant what the maximum application rates per season and per year would be for use patterns where the combined application regimen was permitted. The registrant provided several clarifications which are provided, along with further details on how this information impacts the subsequent modelling, within Appendix D. For seed treatment applications, one of the limiting factors in modeling exposure EECs from treated seeds is the seeding depth. The model estimates no exposure (i.e. EECs= zeros) for seeds planted at depths >2 cm. Canola, flax/crambe and sorghum were the only seed use pattern modeled alone while others were modeled in combination with soil and/or foliar applications.

Table 3-6. Modeled Application Rates for Various Agricultural Use Patterns of Imidacloprid Application Rate Used for modeling (Kg. Selected Application Method Use Pattern (Crop a.i/ha)1 Rate Group/Subgroup) Seed Soil Foliar Total (Notes) 0 0.561 0 0.561 Soil rate Artichoke, Globe 0 0 0.1402 x 4 @ 14 d. 0.561 Foliar rate 0 0.561 0.561 Soil rate Banana and Plantain 0 0 0.1121 x 5 @ 14 d. 0.561 Foliar rate Brassica (cole) Vegetables (05) 0 0.296 0.053 x 5 @ 5 d. 0.561* Reduced Soil rate + Foliar rate Beans-Peas (6) 0.561 0 0 0.561 Seed rate Seed rate + Reduced Soil rate + Broccoli (5A) 0.206 0.089 0.053 x 5 @ 5 d. 0.561 Foliar rate Seed rate + Reduced Soil rate + Mustard (5B) 0.078 0.217 0.053 x 5 @ 5 d. 0.561 Foliar rate Bulb Vegetables (3) 0 0.561 0 0.561 Soil rate 0 0.561 0 0.561 Soil rate Bushberry (13-7-B) and 0 0 0.1121 x 5 @ 7 d. 0.561 Foliar rate for Bushberry Caneberry (13-A) Reduced Soil rate + Foliar rate 0 0.224 0.1121 x 3 @ 7 d. 0.561 for Caneberry Seed rate + Reduced Soil rate + Carrots (1A/B) 0.115 0.298 0.049 x 3 @ 5 d. 0.561 Foliar rate For labeled cereal grain uses such as barley, corn, buckwheat, millet, oats, rye, Cereal Grains, except sorghum teosinte, triticale, and wheat, while applications rates vary, planting depth are (15) greater than 2 cm which modelling will return “0” for EECs. Citrus (10) 0 0 0.2805 x 2 @ 10 d. 0.561 Foliar rate

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Application Rate Used for modeling (Kg. Selected Application Method Use Pattern (Crop a.i/ha)1 Rate Group/Subgroup) Seed Soil Foliar Total (Notes) 0 0.561 0 0.561 Soil rate Seedling rate + Reduced Soil 0.270 0.291 0 0.561 rate Seedling rate + Reduced Foliar 0.270 0 0.291 x1 0.561 rate Coffee 0 0.561 0 0.561 Soil rate Seed rate + Reduced Soil rate + Cotton 0.106 0.119 0.067 x 5 @ 7 d. 0.561 Foliar rate Soil rate Cranberry (13-07G/H) 0 0.561 0 0.561 (see Appendix D for further information on this use) Cucurbit Vegetables (09) 0 0.426 0 0.426* Soil rate 0 0.561 0 0.561* Soil rate for peppers Fruiting Vegetables (08): Peppers Seedling rate + Reduced Soil 0.052 0.239 0.090 x 3 @ 5 d. 0.561* rate + Foliar rate Seedling rate + Reduced Soil 0.036 0.120 0.090 x 3 @ 5 d. 0.561* Fruiting Vegetables (08): Others rate + Foliar rate 0 0.426 0 0.561* Soil rate for tomatoes & others 0 0.561 0 0.561 Soil rate Grape (13-07F) 0 0.449 0.056 x 2 @ 14 d. 0.561 Reduced Soil rate + Foliar rate Herbs & Spices (19-A) 0 0.417 0.048 x 3 @ 5 d. 0.561* Reduced Soil rate + Foliar rate Hops 0 0.225 0.112 x 3 @ 21 d. 0.561 Reduced Soil rate + Foliar rate Leafy Green Vegetables (04-A) 0 0.296 0.053 x 5 @ 5 d. 0.561* Reduced Soil rate + Foliar rate Leafy Petiole vegetables (04-B) 0 0.426 0 0.426* Soil rate Leek (3-07A) 0.204 0.356 0 0.561 Seed rate + Reduced Soil rate Legume Vegetables (6-C), except 0 0.417 0.048 x 3 @ 7 d. 0.561 Reduced Soil rate + Foliar rate Soybeans Oilseed, canola/rape (20) 0.092 0 0 0.092 Seed rate Oilseed, flax/crambe (20) 0.505 0 0 0.505 Seed rate Onion (3-07B) 0.178 0.382 0 0.561 Seed rate + Reduced Soil rate 0 0.414 0.049 x 3 @ 5 d. 0.561 Reduced Soil rate + Foliar rate Peanuts Seed rate + Reduced Soil rate + 0.159 0.254 0.049 x 3 @ 5 d. 0.561 Foliar rate 0 0 0.2805 x 2 @ 10 d. 0.561 Foliar rate Pome Fruits (11): Pears Reduced Soil rate + Reduced 0 0.281 0.2805 x 1 0.561 Foliar rate 0 0 0.1121 x 5 @ 10 d. 0.561 Foliar rate Pome Fruits (11): All Others Reduced Soil rate + Reduced 0 0.224 0.1121 x 3 @ 10 d. 0.561 Foliar rate 0 0.561 0 0.561 Soil rate Pomegranate 0 0.224 0.1121 x 3 @ 7 d. 0.561 Reduced Soil rate + Foliar rate 0 0.337 0.056 x 4 @ 7 d. 0.561 Reduced Soil rate + Foliar rate Potato (1C) 0.561 0 0 0.561 Potato Seed pieces rate

37

Application Rate Used for modeling (Kg. Selected Application Method Use Pattern (Crop a.i/ha)1 Rate Group/Subgroup) Seed Soil Foliar Total (Notes) Root Vegetables (01-B) except 0 0.414 0.049 x 3 @ 5 d. 0.561 Reduced Soil rate + Foliar rate Sugarbeet Sorghum (15) 0.026 0 0 0.026 Seed rate Soybeans (06) 0.235 0 0.0523 x 3 @ 7 d. 0.392 Seed rate + Foliar rate Stone Fruits (12): Apricot, 0 0.224 0.1121 x 3 @ 7 d. 0.561 Reduced Soil rate + Foliar rate Nectarine & Peach Reduced Soil rate + Reduced 0 0.224 0.1121 x 3 @ 10 d. 0.561 Stone Fruits (12): Cherries, Plums, Foliar rate Plumcot, Prune 0 0 0.1121 x 5 @ 10 d. 0.561 Foliar rate 0 0.561 0 0.561 Soil rate Strawberry (13-07G) 0 0.402 0.053 x 3 @ 5 d. 0.561 Reduced Soil rate + Foliar rate Sugarbeet (1A) 0.481 0 0.561 Seed rate 0.561 0 0 0.561 Soil rate Tobacco 0 0.249 0.052 x 6 @ 7 d. 0.561 Reduced Soil rate + Foliar rate 0 0.561 0 0.561 Soil rate and also Seedling rate Tree nuts (14) Seed rate + Reduced Soil rate + 0 0.161 0.100 x 4 @ 6 d. 0.561 Foliar rate 0 0.561 0 0.561 Soil rate Tropical Fruits (23 and 24) Seed rate + Reduced Soil rate + 0 0 0.1121 x 5 @ 10 d. 0.561 Foliar rate Seed rate + Reduced Soil rate + Tuberous Corm Vegetables (01-C) 0 0.414 0.049 x 3 @ 5 d. 0.561 Foliar rate Reduced Soil rate + Foliar rate Watercress (4A) 0 0.296 0.053 x 5 @ 5 d. 0.561 (See Appendix D for further information on this use) 1 Seed refers to treated seed or seedling; Rates in red bold are the rates reduced to achieve the combined seasonal label rates used in modeling noting that most of the reduction was for the soil rate; Total rate= seasonal rate= yearly rate except for use patterns identified by * for which the seasonal rate must be multiplied by three to arrive at the yearly rate. 2Where applicable

Non-Agricultural Use Patterns

Use patterns detailed in Appendix A were used to obtain the required parameters for modeling which are summarized in Table 3-7. Along with use patterns identified in Table 3-7, imidacloprid is also registered for residential and commercial structures as a perimeter treatment. These uses are discussed extensively in Appendix D which includes modelling assumptions and schematics that illustrate those assumptions.

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Table 3-7. Modeled Application Rates for Various Non-Agricultural Use Patterns of Imidacloprid Application Rate Used for modeling (Kg. a.i/ha)2 Use Pattern Soil Foliar Total 0.448 0 0.448 Nurseries 0 0.448 0.448 0.561 0 0.561 Poplar/cottonwood/Forestry 0 0.1121 x 5 @ 10 d. 0.561 0.561 0 0.561 Christmas Trees 0 0.1121 x 5 @ 7 d. 0.561 Turf 0.561 0 0.561 Perimeter Treatment 0.561 0 0.551

D. Application Methods

Ground, aerial and/or air-blast equipment are used to deliver liquid spray applications to plant foliage (i.e., foliar application). In this case, the application method selected for PWC modeling is “above crop”. For soil application, many methods of ground application are used to deliver imidacloprid formulation into the soil as a liquid spray. Most of the soil application methods are used to place the pesticide below the soil surface and into the seed or root zone of the crop. In order to achieve placement of the pesticide at the proper depth, more than one method may be used depending on the crop and at what stage it is to be treated. These methods may be categorized into two categories depending on the time at which the method may be used. Category descriptions, detailed tables by method and use pattern, and further information on planting depths are found within Appendix D.

E. Drift Fraction

Imidacloprid labels calls for buffer zones to reduce drift from ground, air-blast and aerial applications. This requires calculations of the reduced drift fractions that will be used for modeling. AgDRIFT was used for these calculations and the results are summarized in Table 3-8.

Table 3-8 Drift Fractions Associated with Varied Imidacloprid Application Procedures Application Procedures Ground Air-blast Aerial Labeled Buffer 25 ft. 25 ft. 150 ft. AgDRIFT Calculated Drift Fraction Used in Modeling 0.0267 0.0150 0.0385

F. Representative scenarios

A table containing the representative scenarios of single or multiple application scenarios used in modeling can be found in Appendix D.

39

3.4.2. Outputs

Aquatic EECs are presented in Table 3-9 – Table 3-12. The tables contain results selected from many runs for each use pattern. The results show the range of EECs resulting from using different application methods. In general, the data show highest EECs from foliar applications, followed by soil applications at depth <2 cm especially if the application produces drift. Aquatic exposure appears to diminish as the pesticide is soil-incorporated, and spray drift is nil.

40

Table 3-9. EECs for Registered Foliar Use Patterns for Imidacloprid. Max 21-d 60-d Application App. App. Annual Peak Average Average Crop Group Use Pattern Scenario (notes1) Rate (lbs Number Interval Rate (lbs (µg a.i/L) (µg (µg a.i/A) a.i/A) a.i/L) a.i/L) CAcitrus_WirrigSTD 0.25 2 10 d 0.50 1.26 0.82 0.51 10 – Citrus Fruits Citrus Fruits FLcitrusSTD 0.25 2 10 d 0.50 15.60 9.88 5.61 WAorchardsNMC 0.25 2 10 d 0.50 1.56 1.08 0.68 Pears WAorchardsNMC 0.25 2 10 d 0.50 11.10 7.43 4.14 11 – Pome Fruits WAorchardsNMC 0.10 5 10 d 0.50 1.44 0.99 0.62 Pome Fruits NCappleSTD 0.10 5 10 d 0.50 6.39 4.35 2.68 CAfruit_WirrigSTD 0.10 5 10 d 0.50 1.64 1.24 0.75 12 – Stone Fruits Cherries MICherriesSTD 0.10 5 10 d 0.50 4.42 3.30 2.15 ORberriesOP (sub-surface 13 - Berries Bushberry 0.10 5 7 d 0.50 2.73 1.99 1.30 spray, 23 cm) 23/24 – Tropical FLcitrusSTD (aerial) 0.10 5 14 d 0.50 1.38 0.98 0.57 Banana and subtropical CAAvocadoRLF_V2 (aerial) 0.10 5 14 d 0.50 2.49 1.63 1.15 fruit (edible and Tropical FLcitrusSTD 0.10 5 10 d 0.50 1.32 0.88 0.56 inedible peel) Tropical CAAvocadoRLF_V2 0.10 5 10 d 0.50 2.61 1.72 1.20 CARowCropRLF_V2 for Artichoke 0.12 4 14 d 0.50 2.23 1.58 1.13 No Crop Group Artichokes (aerial) Coffee PRcoffeeSTD 0.10 5 7 d 0.50 11.90 8.08 4.51 Christmas Trees ORXmasTreeSTD 0.10 5 7 d 0.50 2.48 1.94 1.27 CAForestryRLF 0.10 5 10 d 0.50 3.94 2.82 1.94 Poplar PAappleSTD_V2 0.10 5 10 d 0.50 5.82 3.89 2.24 CAnurserySTD_V2 0.40 1 -- 0.40 3.59 2.37 1.33 Nurseries TNnurserySTD_V2 0.40 1 -- 0.40 15.50 10.20 5.69 CATurfRLF 0.50 1 -- 0.50 2.07 1.43 0.98 Non-Agricultural FLturfSTD 0.50 1 -- 0.50 3.74 2.36 1.30 CATurfRLF (Foliar/granular broadcast 0.50 1 NA 0.50 1.34 0.95 0.61 Turf – CA) FLturfSTD (Foliar/granular broadcast 0.50 1 NA 0.50 3.18 2.00 1.07 – FL) 1Where applicable

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Table 3-10. EECs for Registered Soil Use Patterns for Imidacloprid. 21-d 60-d Peak Application Average Average Crop Group Use Pattern Scenario (notes1) (µg Rate (µg (µg a.i/L) a.i/L) a.i/L) CAonion_WirrigSTD 0.50 3.46 2.34 1.35 3 – Bulb Vegetables Bulb Vegetables GAOnion_WirrigSTD 0.50 5.69 3.64 3.56 CARowCropRLF_V2 for celery (Soil at 10 cm depth) 0.38 0.36 0.28 0.17 4 – Leafy Vegetables Leafy petiole CARowCropRLF_V2 for celery (Soil at 0.64 cm depth) 0.38 2.23 1.69 1.04 8 – Fruiting Vegetables Peppers FLpeppersSTD 0.50 5.23 3.57 1.97 CAMelonsRLF_V2 (Seed depth 1.27 cm – CA) 0.38 0.23 0.15 0.08 FLcucumberSTD (Seed depth 1.85 cm – FL) 0.38 0.64 0.40 0.47 9 – Cucurbit Vegetables Cucurbit Vegetables FLcucumberSTD (Seed depth >2 cm – FL) 0.38 1.33 0.83 0.82 FLcucumberSTD (Drench to 10 cm) – FL) 0.38 3.13 1.94 1.26 FLcucumberSTD (Seed depth 1.27 cm) – FL) 0.38 4.51 2.80 2.11 FLcitrusSTD (Drench – FL) 0.50 0.40 0.26 0.14 10 – Citrus Fruits Citrus Fruits FLcitrusSTD (Chemigation – FL) 0.50 1.01 0.66 0.39 Bushberries ORberriesOP (Drenched at 45 cm) 0.50 0.26 0.19 0.11 CAgrapes_WirrigSTD 0.50 0.57 0.38 0.22 Grapes NYGrapesSTD 0.50 1.87 1.29 0.80 13 – Berries FLstrawberry_WirrigSTD (chemigation) 0.50 2.18 1.59 0.91 Strawberries CAStrawberry-noplasticRLF_V2 (chemigation) 0.50 2.38 1.72 0.98 Dry Field Site – OR Berries with Providence, RI weather 0.50 7.16 5.22 3.14 Cranberry Treated bog sites - PFAM 0.50 11.7 6.99 3.64 GAPecansSTD (drench) 0.50 0.25 0.18 0.19 14 – Tree Nuts Tree Nuts CAalmond_WirrigSTD (drench) 0.50 1.32 0.84 0.46 Bananas CAAvocadoRLF_V2 0.50 0.30 0.19 0.11 23/24 – Tropical and FLavocadoSTD 0.50 0.15 0.10 0.05 Pomegranate subtropical fruits (edible CAfruit_WirrigSTD (chemigation) 0.50 0.30 0.20 0.11 and inedible peels) FLavocadoSTD 0.50 0.06 0.04 0.03 Tropical CAAvocadoRLF_V2 0.50 0.12 0.08 0.05 CARowCropRLF_V2 for Artichokes (chemigation) 0.50 0.47 0.37 0.24 Artichoke CARowCropRLF_V2 for Artichokes (seeded/soil) 0.50 5.13 3.50 2.02 No Crop Group Coffee PRcoffeeSTD (soil injected) 0.50 0.00 0.00 0.00 Tobacco NCtobaccoSTD (drench planting at planting, 10 cm) 0.50 0.36 0.23 0.13 Non-Agricultural Poplar CAForestryRLF (chemigation) 0.50 0.48 0.33 0.19

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21-d 60-d Peak Application Average Average Crop Group Use Pattern Scenario (notes1) (µg Rate (µg (µg a.i/L) a.i/L) a.i/L) PAappleSTD_V2 (chemigation) 0.50 0.63 0.42 0.24 CAForestryRLF (soil shanked in 20 cm) 0.50 0.00 0.00 0.00 ORXmasTreeSTD (shanked in 20 cm) 0.50 0.00 0.00 0.00 Christmas trees ORXmasTreeSTD (chemigation) 0.50 0.35 0.26 0.15 Granular/watered-in, 10 cm (TN) 0.40 0.68 0.45 0.25 Nurseries Granular/watered-in, 10 cm (CA) 0.40 3.45 2.26 1.26 Residential Perimeter CA Residential 0.50 0.390 0.258 0.181 Treatment TX Residential 0.50 1.81 1.32 0.776 Commercial CA Commercial 0.50 0.01 0.00896 0.00773 Perimeter Treatment FL Commercial 0.50 0.200 0.13 0.079 1Where applicable

Table 3-11. EECs for Registered Seed Treatment Use Patterns for Imidacloprid. Peak 21-d 60-d Single App. Crop Group Use Pattern Scenario (notes1) (µg Average Average Rate a.i/L) (µg a.i/L) (µg a.i/L) 1 – Root and Tuber Sugarbeet CAsugarbeet_WirrigOP 0.43 1.20 0.84 0.51 Vegetables Potato See footnote 2. 0.50 0.00 0.00 0.00 ILbeansNMC; ORsnbeansSTD2. Yes, if seed 6 – Legume Vegetables Beans/peas treatment only. you get zero for both 0.50 0.00 0.00 0.00 scenarios, because of the > 2cn depth KSsorghumSTD; 0.02 0.01 0.01 0.00 15 – Cereal Grains Sorghum TXsorghumOP 0.02 0.02 0.01 0.01 Canola/rapeseed NDcanolaSTD 0.08 0.65 0.52 0.34 20 - Oilseed TXwheatOP 0.45 0.16 0.11 0.06 Flax, crambe CAWheatRLF_V2 0.45 1.10 0.71 0.39 1Where applicable 2Scenario associated with planting depth of more than 2 cm. As a result, all EECs returned are “0”. Refer to Table 3-8 for further details.

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Table 3-12. EECs for Registered Combined Application Method Use Patterns for Imidacloprid. Seed / 21-d 60-d Max Annual Peak Seedling Soil App. Foliar Rate2 Average Average Crop Group Use Pattern Scenario (notes1) Rate (µg App. Rate (Notes)3 (µg (µg (combined) a.i/L) Rate a.i/L) a.i/L) FLpotatoNMC 0.20 (Soil-chemigation/foliar – -- 0.30 0.50 0.63 0.53 0.33 (0.05; 4; 7) FL) Potatoes CAPotatoRLF_V2 0.20 (Soil-chemigation/foliar – -- 0.30 0.50 3.96 2.76 1.76 (0.05; 4; 7) CA) NCSweetPotatoSTD 0.13 (Soil-shanked in 2.54 -- 0.37 0.50 1.46 0.96 0.54 1 – Root and Tuberous/Corm (0.044; 3; 5) cm/foliar) Tuber Vegetables 0.13 Vegetables NCSweetPotatoSTD -- 0.37 0.50 2.98 2.09 1.33 (0.044; 3; 5) FLcarrotSTD 0.13 (Seed/Soil at 2.54 0.10 0.27 0.50 13.30 8.48 4.84 (0.044; 3; 5) Carrots cm/Foliar FLcarrotSTD 0.13 0.10 0.27 0.50 14.10 9.98 5.77 (Seed/Chemigation/Foliar) (0.044; 3; 5) Root vegetables (whole 0.13 FLcarrotSTD -- 0.37 0.50 33.90 21.30 13.30 group except sugarbeet) (0.044; 3; 5) CAonion_WirrigSTD 0.18 0.32 -- 0.50 0.87 0.58 0.35 (Seed/Soil – CA) Leek GAOnion_WirrigSTD 0.18 0.32 -- 0.50 8.35 5.56 3.08 3 – Bulb (Seed/Soil – GA) Vegetables CAGarlicRLF_V3 0.16 0.34 -- 0.50 0.80 0.53 0.30 (Seed/Soil – CA) Onion CAonion_WirrigSTD 0.16 0.34 -- 0.50 7.63 5.08 2.82 (Seed/Soil – CA) CAlettuceSTD 0.24 0.26 -- 0.50 4.19 3.04 1.85 (Soil (drench)/foliar) (0.047; 5; 5) Leafy Greens 4 – Leafy CAlettuceSTD 0.24 0.26 -- 0.50 13.60 9.89 5.62 Vegetables (Soil/foliar) (0.047; 5; 5) PFAM Scenario (Knoxville, 0.24 Watercress -- 0.26 0.50 8.60 1.41 0.952 TN Weather; Soil+Folair) (0.047; 5; 5)

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Seed / 21-d 60-d Max Annual Peak Seedling Soil App. Foliar Rate2 Average Average Crop Group Use Pattern Scenario (notes1) Rate (µg App. Rate (Notes)3 (µg (µg (combined) a.i/L) Rate a.i/L) a.i/L) FLcabbageSTD 0.24 -- 0.26 0.50 8.71 6.63 4.01 (Soil/foliar – FL) (0.047; 5; 5) Brassica (whole group) CAColeCropRLF_V2 0.24 5 – Brassica -- 0.26 0.50 9.49 6.80 4.09 (Soil/foliar – CA) (0.047; 5; 5) (Cole) Leafy 0.24 Vegetables Broccoli CAColeCropRLF_V2 0.18 0.08 0.50 7.74 5.44 3.28 (0.047; 5; 5) 0.24 Mustard CAColeCropRLF_V2 0.07 0.19 0.50 4.79 3.39 2.33 (0.047; 5; 5) ORsnbeansSTD 0.13 -- 0.37 0.50 2.95 2.18 1.41 Legume (whole group (Soil/foliar) (0.04; 3; 7) except soybean) ILbeansNMC 0.13 -- 0.37 0.50 5.59 4.00 3.30 6 – Legume (Soil/foliar) (0.04; 3; 7) Vegetables MSsoybeanSTD 0.14 0.21 -- 0.35 1.84 1.18 0.77 (Seed/foliar – early May) (0.047; 3; 7) Soybean MSsoybeanSTD 0.14 0.21 -- 0.35 2.86 2.00 1.23 (Seed/foliar – early April) (0.047; 3; 7) FLpeppersSTD 0.24 Peppers (Transplants/Soil/Foliar – 0.046 0.21 0.24 6.29 4.71 2.68 (0.08; 3; 5) FL) CAtomato_WirrigSTD 8 – Fruiting 0.24 (Transplants/Soil/Foliar – 0.036 0.11 0.37 1.61 1.15 0.82 Vegetables 0.08; 3; 5) Fruiting vegetables CA) (except peppers) FLtomatoSTD 0.24 (Transplants/Soil/Foliar – 0.036 0.11 0.37 10.30 7.68 4.48 0.08; 3; 5) FL) FLcitrusSTD 0.24 0.26 -- 0.50 0.82 0.54 0.32 10 – Citrus Citrus fruits (whole (Transplant/Soil Fruits group) FLcitrusSTD 0.26 0.24 -- 0.50 6.71 4.53 2.47 (Transplant/Foliar) (0.26; 1; NA) WAorchardsNMC 0.30 11 – Pome Pome fruits (whole (Soil-chemigation/foliar – -- 0.20 0.50 0.98 0.68 0.44 (0.1; 3; 10) Fruits group) WA) NCappleSTD -- 0.20 0.30 0.50 5.46 3.73 2.12

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Seed / 21-d 60-d Max Annual Peak Seedling Soil App. Foliar Rate2 Average Average Crop Group Use Pattern Scenario (notes1) Rate (µg App. Rate (Notes)3 (µg (µg (combined) a.i/L) Rate a.i/L) a.i/L) (Soil-chemigation/Foliar – (0.1; 3; 10) NC) CAfruit_WirrigSTD; 0.30 (Soil-chemigation/foliar – -- 0.20 0.50 1.11 0.81 0.64 (0.1; 3; 7) CA) Apricot, nectarine, peach GAPeachesSTD 0.30 (Soil-chemigation/foliar – -- 0.20 0.50 2.13 1.47 0.90 (0.1; 3; 7) 12 – Stone GA) Fruits CAfruit_WirrigSTD; 0.30 (Soil-chemigation/foliar – -- 0.20 0.50 1.50 1.01 0.57 (0.1; 3; 10) CA) Cherries, plums MICherriesSTD 0.30 (Soil-chemigation/foliar – -- 0.20 0.50 3.10 2.14 1.35 (0.1; 3; 10) MI) 0.30 Bushberry ORberriesOP -- 0.20 0.50 2.46 2.03 1.27 (0.1; 3; 7) CAStrawberry- 0.14 noplasticRLF_V2 -- 0.36 0.50 2.56 1.61 0.97 (0.047; 3; 5) (Soil-chemigation/foliar) Strawberry CAStrawberry- 13 – Berries 0.14 noplasticRLF_V2 -- 0.36 0.50 3.64 2.47 1.45 (0.047; 3; 5) (Soil-chemigation/foliar) CAgrapes_WirrigSTD; 0.10 -- 0.40 0.50 0.69 0.48 0.30 (Soil/foliar – CA) (0.05; 2; 14) Grape NYGrapesSTD 0.10 -- 0.40 0.50 2.20 1.78 1.22 (Soil/foliar – NY) (0.05; 2; 14) ORfilbertsSTD 0.36 -- 0.14 0.50 3.60 2.56 1.73 14 – Tree (Soil drench/foliar – OR) (0.09; 4; 6) Tree nuts (whole group) Nuts GAPecansSTD 0.36 -- 0.14 0.50 6.40 4.33 2.42 (Soil drench/foliar – GA) (0.09; 4; 6) ORmintSTD 0.13 19 – Herbs Herbs and Spices (whole -- 0.37 0.50 1.37 0.94 0.55 (Soil-chemigation/foliar) 0.043; 3; 5) and Spices group) ORmintSTD -- 0.37 0.13 0.50 3.02 2.22 1.47

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Seed / 21-d 60-d Max Annual Peak Seedling Soil App. Foliar Rate2 Average Average Crop Group Use Pattern Scenario (notes1) Rate (µg App. Rate (Notes)3 (µg (µg (combined) a.i/L) Rate a.i/L) a.i/L) (Soil/foliar) 0.043; 3; 5) CAcotton_WirrigSTD 0.30 0.095 0.11 0.50 0.51 0.39 0.31 (Seed/soil/foliar – CA) (0.06; 5; 7) 20 – Oilseed Cotton STXcottonNMC 0.30 0.095 0.11 0.50 8.95 6.26 3.38 (Seed/soil/foliar – TX) (0.06; 5; 7) 23/24 – Tropical and subtropical CAfruit_WirrigSTD 0.30 Pomegranate -- 0.20 0.50 1.61 1.18 0.71 fruits (edible (Soil-chemigation/foliar) (0.1; 3; 7) and inedible peel) 0.30 Hops ORhopsSTD -- 0.20 0.50 0.80 0.55 0.37 (0.1; 3; 21) NCtobaccoSTD 0.28 Tobacco (Soil drench/foliar – 2 -- 0.22 0.50 0.88 0.65 0.44 (0.046; 6; 7) No crop weeks later) group NCpeanutSTD 0.13 (Seed/soil- 0.14 0.23 0.50 2.03 1.41 0.81 (0.043; 3; 5) Peanuts chemigation/foliar) NCpeanutSTD 0.13 -- 0.37 0.50 2.18 1.49 0.85 (Soil-seed depth/foliar) (0.043; 3; 5) 1Where applicable 2Foliar rate is combined maximum of all permitted single application rates 3Single application rate; number; interval (days)

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3.5. Aquatic Exposure Monitoring

3.5.1. Surface Water Monitoring Data

Modeling is currently used by the Agency to arrive at required estimates of surface water pesticide concentrations for use quantitatively in risk assessment. This is done in a manner that attempts to ensure that pesticide exposure is not underestimated. In contrast, available monitoring data are used qualitatively to inform interpretation of modeled concentrations. Efforts are ongoing within EFED to 19 develop ways to insure availability of quality monitoring data18F , and to develop methods (e.g., Bias 20 21 Factors19F , SEAWAVEQ20F ) to address uncertainty so that available monitoring data can be employed in a 22 more quantitative manner. As pointed out by Bohaty et al,21F modeling comprises computer simulation of fate and transport of pesticides to generate EECs, while monitoring necessarily consists of limited empirical field data. Each provides different kinds of information, but when interpreted properly, they can complement one another. As stated previously, modeling is used for quantitative risk assessment because it represents known physical-chemical processes in conservative though plausible scenarios, and can be used to simulate maximum or alternative pesticide label use rates. In contrast, monitoring data are typically used only qualitatively in risk assessment because of inherent environmental variability and limited availability of data on most pesticides. In addition, important auxiliary data are not always available for monitoring data sets (e.g., study purpose, design, date, location, media sampled, analytical method limits of detection/quantification (LOD/LOQ), sample collection method, meteorological data, nearby pesticide usage, and soil, hydrologic and other environmental conditions at sampling sites).

Available monitoring data for imidacloprid may be described as relatively abundant in comparison with data for other pesticides. Most of these data contain important auxiliary information, but lack specificity in terms of information on imidacloprid usage in monitored watersheds. Most of these data were generated by the USGS for multiple pesticides at locations selected to represent nationwide coverage, and were not specially designed for monitoring imidacloprid. This type of data may be useful to suggest lower bounds on aquatic concentrations, or for longer-term exposure estimates because monitoring is usually done at long intervals between sampling. Other types of data were also considered, including a subset from the USGS that were targeted towards specific kinds of hydrological events such as storms and floods. Data from the California Department of Pesticide Regulation (CDPR) were also included. CDPR data were targeted towards simultaneous monitoring of multiple pesticides, including imidacloprid, in water bodies receiving runoff and/or spray drift in agricultural/urban and mixed-use watersheds. Finally, monitoring data reported in the literature were also included. The latter data were

19 Guidance for submission of water quality data, URL: http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm 20 J. Hetrick, 2012. Strengths and limitations of the bias factor approach. White paper, FIFRA SAP Meeting, June, 2012, Crystal city, VA. 21 J. Hetrick et al, 2016 Integration of SEAWAVEQ model predictions into bias factor development. 252nd American Chemical Society National Meeting, Philadelphia, PA. 22 R.F.H. Bohaty et al, 2016. 252nd American Chemical Society National Meeting, Philadelphia, PA.

48 originally collected for research-specific goals but may be useful in providing perspective on expected concentrations in the environment at specific sites and under specific conditions.

A. Non-Targeted Surface Water Monitoring Data

23 A collection of seventeen years of nationwide monitoring data for imidacloprid was downloaded22F , summarized (Table 3-13), displayed graphically (with sampling times) and spatially throughout the nation (Figure 3-9 and Figure 3-10, respectively). Nationwide usage data for monitored years were also displayed in the same graph. Sources of data include: the USGS’ National Water Information System (NWIS) and the EPA’s STOrage and RETrieval and Water Quality Exchange (STORET). The source of imidacloprid in surface waters is the chemical’s agricultural and non-agricultural usage. As shown in Figure 3-3, imidacloprid usage steadily, but gradually, increased from nearly ¼ to ½ million lbs. during the period from the year 2000 through 2006. In the years 2007, 2008 and 2009, usage increased to nearly ¾ million lbs. From 2010 through 2014 usage sharply increased to between 1.5 and 2 million lbs. In relative terms, three periods of usage may be recognized: low usage period (2000 up to and including 2006), medium usage period (years 2007/08/09) and high usage period (2010 up to and including 2014). In contrast, intensity of monitoring streams (i.e., number of samples/year and length of intervals between sampling) decreased substantially during years of medium and high usage compared with the years of low usage. For example, relatively high intensity sampling was conducted in the period from the year 2000 to the year 2006 (7-17% of the total) compared to the years from 2007 to 2016 (1-5% of the total). One exception is the year 2010 in which more than 500 samples were collected (12% of the total number of samples). However, in the case of rivers and lakes, low intensity of monitoring occurred in the low and medium-usage period (<1-4% of a total of nearly 3000 samples), compared to relatively high intensity monitoring during the period of high usage (10-17% of the total). In general, it may be stated that monitoring data intensity were relatively reasonable (compared to other chemicals) for streams during the years 2000 up to and including 2006 and 2010. Reasonable monitoring intensity for lakes and rivers was executed for the years 2010 through 2014.

Monitoring data were available for 1,667 sites, with 7,933 samples taken from 1999 to 2016 (Table 3-13). Types of monitored surface waters included drainage canals, variable sizes of streams, rivers, lakes, in addition to wetlands and estuaries. Stream and river catchments ranged in size from <1 sq. mile to 176,333 sq. miles. Land use ranged from dominantly urban to dominantly agricultural, with varied mixtures of urban and agricultural land. Varied limits of detections (LODs) are apparent in the data, from 2 ng/L for the most recent data to 106 ng/L for older data, with a few data points having LODs >106 ng/L. Most of the data had LODs between 2 and 20 ng/L.

Table 3-13. Summary Statistics for the USGS Nationwide Monitoring Data No. of No. of Detections (ng/L) LOD (ng/L) Item Sites Samples Min Max Min Max Drainage Canals Ditches (2013-2014) Total Number of Detects 1 5 11 3.5 1,600 NR NR

23 National Water Quality Monitoring Council, Water Quality Data. URL (10-Nov-2016): http://www.waterqualitydata.us/portal/ 49

No. of No. of Detections (ng/L) LOD (ng/L) Item Sites Samples Min Max Min Max Total Number of Non-Detects 6 7 0.0 0.0 NR NR Grand Total 11 18 Detection: 61% Streams (Sampling dates: 1999-2016) Sites Sampled > 10 times 9 405 6.0 7,940 6.8 106 Sites Sampled <10-5 times 7 45 5.0 488 2.0 106 Sites Sampled <5-1 times 80 121 4.0 1,300 NR; 6.8 NR; 106 Total Number of Detects 96 571 4.0 7,940 Sites Sampled > 10 times 113 2,674 0.0 0.0 NR; 2 NR; 400 Sites Sampled <10-5 times 58 385 0.0 0.0 NR; 2 NR; 106 Sites Sampled <5-1 times 404 642 0.0 0.0 NR; 2 NR; 106 Total Number of Non-Detects 575 3,701 0.0 0.0 Grand Total 671 4,272 Detection: 13% Rivers and Lakes (Sampling dates: 1999-2016) Sites Sampled > 10 times 2 26 1.4 708 NR; 20 NR; 60 Sites Sampled <10-5 times 3 15 2.0 618 NR; 60 NR; 60 Sites Sampled <5-1 times 64 106 1.8 240 ND; 2 NR; 60 Total Number of Detects 69 147 1.4 708 Sites Sampled > 10 times 61 1,626 0.0 0.0 2; NR 106; NR Sites Sampled <10-5 times 73 456 0.0 0.0 2; NR 120; NR Sites Sampled <5-1 times 544 755 0.0 0.0 2; NR 106; NR Total Number of Non-Detects 678 2,837 0.0 0.0 Grand Total 747 2,984 Detection: 5% Wetland (2001 & 2014) Total Number of Detects 1 2 2 25.2 76.8 20 20 Total Number of Non-Detects 22 22 0.0 0.0 6.8; NR 60; NR Grand Total 24 24 Detection: 8% Estuaries (2002; 2004; 2006; 2012- 2014) Sites Sampled <10-5 times 6 52 1.3 4 NR NR Sites Sampled <5-1 times 2 2 9.7 18 NR NR Total Number of Detects 1 8 54 1.3 18 NR NR Total Number of Non-Detects 21 27 0.0 0.0 Grand Total 29 81 Detection: 67% 1All Sites were sampled <5-1 times; LOD= Limit of detection

In monitored streams, most detected concentrations were below 1,000 ng/L, however 18 streams had detections ranging from 1,000 to 7,940 ng/L (Figure 3-9). In general, concentrations in streams were about an order of magnitude higher than concentrations monitored in rivers and lakes. Due to the apparent variability in the monitoring effort, no conclusions may be drawn regarding trends in imidacloprid concentrations during the period from 2000 to 2014. The apparent decrease in concentrations in streams is in contrast to the sharp increase in usage during this same time period, as described previously. The observed decrease in monitored concentrations might be explainable as the result of shifts in crop usage patterns and/or formulations, because modeling suggests that imidacloprid applied to soil results in lower surface water concentrations than imidacloprid applied to foliage, especially if soil application is combined with incorporation, watering-in and/or injection.

50

↨ 99 ↨ 00 ↨ 01 ↨ 02 ↨ 03 ↨ 04 ↨ 05 ↨ 06 ↨ 07 ↨ 08 ↨ 09 ↨ 10 ↨ 11 ↨ 12 ↨ 13 ↨ 14 ↨ 15 Monitoring Dates (99= 1999; 00= 2000; 01= 2001)

↨ 99 ↨ 00 ↨ 01 ↨ 02 ↨ 03 ↨ 04 ↨ 05 ↨ 06 ↨ 07 ↨ 08 ↨ 09 ↨ 10 ↨ 11 ↨ 12 ↨ 13 ↨ 14 ↨ 15 Monitoring Dates (99= 1999; 00= 2000; 01= 2001)

Figure 3-9. USGS Monitoring Data for Streams, Rivers and Lakes Compared to Usage Data for the Same Years.

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Figure 3-10. Spatial Distribution of the National Monitoring Data (With Detects & Non-Detects; 2014 Crop Layer on the Background)

52

B. Targeted Surface Water Monitoring Data

GA Surface water monitoring data

Concentrations in surface water were monitored in Sope Creek and the Chattahoochee River in Georgia 24 (M. L. Hladik)23F . Sope Creek, near Marietta, Georgia, is an urban site with a catchment of 79.5 square kilometers. Chattahoochee River, near Whitesburg, Georgia (catchment size 6,290 square kilometers), is downstream of Sope Creek and of metropolitan Atlanta and integrates forest, urban and agricultural land uses within its basin. Monitored concentrations in the creek and river are summarized in Figure 3-11.

Figure 3-11. Detected Concentrations of Imidacloprid in Sope Creek and Chattahoochee River, GA (4- Oct-2011 to Apr-4-2012).

Data in Figure 3-11 indicate that Sope Creek had imidacloprid detections throughout the sampling period of October, 2011 through April, 2012. Concentrations ranged from 4.5 to 35.3 ng/L with a detection frequency of 85% (LOD=4.9 ng/L) Highest concentrations were detected in winter. In comparison, the Chattahoochee River had lower detections, in the range of non-detect to 10.1 ng/L with lower frequency of detection of 60%. No usage data are reported for the watersheds associated with the creek or the river.

24 Michell L. Hladik and Daniel L. Calhoun. Analysis of the Herbicide Diuron, Three Diuron Degradates, and Six Neonicotinoid Insecticides in Water- Method Details and Application to two Georgia Streams. Report 2012-5206; US Geological Survey. Available at http://pubs.usgs.gov/sir/2012/5206.

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CA Surface water monitoring data

25 A data set of surface water monitoring was downloaded from CDPR website24F along with the associated 26 reports25F . Monitoring covered water bodies in dominantly urban and dominantly agricultural watersheds. A summary of the data is included in Table 3-14 for agricultural waterbodies/watersheds, and in Table 3-15 for urban waterbodies/watersheds.

Table 3-14. Summary Statistics for CDPR Monitoring Data (Agricultural Waterbodies/Watersheds) Study Sampling No. Of Detects/ Concentration (ng/L) LOR Counties Watershed/Water Body Number Period Sites No. % Min. Max. (ng/L) Santa Cruz, Agriculture Areas (creeks, Monterey, San Luis 2008- rivers, lakes, drainage 252-262 Obispo, Santa 16 25/28 89% 80 1,240 50 2010 ditches): Salinas River, Alamo Barbara, Merced, River, Salton Sea Imperial Agriculture & Mixed Agriculture Areas (creeks, rivers, lakes, drainage ditches): Salinas River, Old Salinas River, Pajaro River,

Imperial, Merced, Santa Maria River, Napa River, Monterey, Napa, Russian River, San Joaquin 2011- San Luis Obispo, 271-278 Watershed, New River, Alamo 50 2012 Santa Cruz, Santa River, Colorado River, Salton Barbara, Riverside, Sea Ventura Parent 31 112/163 69% 50 6,390 Guanidine 30/64 47% Guanidine Olefin 0/64 0% Olefin 0/64 0% Urea 2/64 3% Agriculture Areas (creeks, Monterey, San Luis rivers, ponds, drainage Obispo, Santa ditches): Salinas River, Old 282 2013 Barbara, San Salinas River, San Joaquin 20 43/51 84% 87 6,800 50 Joaquin, Merced, River, Santa Maria River, New Imperial, Riverside River, Alamo River, Colorado River, Salton Sea Agriculture Areas (creeks, Monterey, San Luis rivers, lakes, drainage Obispo, Santa ditches): Salinas River, Old 290 2014 23 51/58 88% 63 9,140 50 Barbara, Imperial, Salinas River, Santa Maria Riverside River, New River, Alamo River, Colorado River, Salton Sea

25 CDPR Surface Water Monitoring of Pesticides Database URL: https://fusiontables.google.com/DataSource?docid=1C0gNYe7stfYxicf_UnG861Hl0sd2j4eCb_DlPSZk#rows:id=1 26 Reports were downloaded from URL: http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps.htm?filter=surfwater

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Study Sampling No. Of Detects/ Concentration (ng/L) LOR Counties Watershed/Water Body Number Period Sites No. % Min. Max. (ng/L) Agriculture Areas (creeks, rivers, lakes, drainage Monterey, San Luis ditches): Salinas River, Old Obispo, Santa 297 2015 Salinas River, Tembladero 26 62/77 81% 52 8,640 50 Barbara, Imperial, Slough, Santa Maria River, Riverside New River, Alamo River, Colorado River, Salton Sea * Time related multiple samples were collected from each site: Data for No. of sites, Detects and concentrations obtained from data from the database. * LOR= 200 for one sample (the 3,308 ng/L sample)

Table 3-15. Summary Statistics for CDPR Monitoring Data (Northern and Southern CA Urban Waterbodies/Watersheds)1,2 Study Sampling No. Of Detects/ Concentration (ng/L) LOR Counties Watershed/Water Body Number Period Sites No. % Min. Max. (ng/L)3 (1) Northern California Sacramento & Roseville Areas: 8 7/32 22% 62 1,840 50 269- 2011- Sacramento Pleasant Grove Creek 11-12 2012 & Placer (Sacramento) & Upper American 7 6/17 35% 50 168 50 River (Folsom) 269- 12- 2012- Sacramento 6 16/24 67% 51 386 50 Same area as above 13 2013 & Placer 1 1/3 33% 166 50 Sacramento & Roseville Areas: Pleasant Grove Creek, Arcade Sacramento, 7 9/30 30% 16 3,308 50* Creek, Miner’s Ravine, Placer, 269- 13- 2013- (Sacramento); Upper American Alameda, 14 2014 River, Curry Creek, Dry Creek Contra (Placer); Kirker Creek, Walnut Costa, 8 4/10 40% 26 62 50 Creek (Contra Costa); South San Ramon Creek (Alameda) Roseville & Folsom (run-off); Folsom, Roseville & Sacramento Sacramento, (creeks & rivers); San Francisco 6 6/20 30% 61 214 50 Placer, Bay (Dublin, Martinez & Santa 269- 14- 2014- Alameda, Clara County Areas: Pleasant 15 2015 Contra Grove Creek, Arcade Creek, Upper Costa, Santa American River, South San Ramon Clara Creek, Walnut Creek, Guadalupe 6 0/13 0% 0 0 50 River, Metcalfe Canyon-Coyote Creek (2) Southern California Southern California 270- 109/15 Los Angeles, Watersheds/Water bodies: 11 69% 20 12,700 20-50 10-14 & 2011- 8 Orange, San Ballona Creek, Bouquet Creek; Salt 270- 14- 2014 Diego Creek, Wood Canyon Creek; 15 7 19/25 76% 21 317 20-50 Chollas Creek, San Diego River 1For each waterbody/watershed entry, top rows refer to storm drains and bottom rows refers to creeks. 2 Time related multiple samples were collected from each site: Data for No. of sites, Detects and concentrations obtained from the database. 3 LOR= 200 for only one sample (the 3,308 ng/L sample) 55

Maps showing the spatial distribution of sites with detections and with no detection is shown in Figure 3-12.

A

B

Figure 3-12 Spatial Distribution of California Monitoring Data (panel A = Detects, panel B = Non- detects)

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Monitoring data for water bodies in agricultural areas show the highest concentrations were found in drainage ditches, creeks and sloughs near agricultural fields (Figure 3-13) as compared with concentrations in rivers and lakes, presumably at least in part as a consequence of relatively little dilution with uncontaminated water. Concentrations found in water bodies associated directly with agricultural fields were generally an order of magnitude or so greater than concentrations found in more distant lakes and rivers.

Figure 3-13. Monitored Concentrations in Ditches, Creeks and Sloughs Compared to Concentrations in Rivers and Lakes

The highest imidacloprid concentrations were observed in single/double storm drains of urban areas compared to tributaries of streams and streams receiving discharge from these drains. In general, imidacloprid found in water bodies in urban areas of northern California is lower in both concentration 57 and detection frequency (DF) than that found in southern California (Conc.=16-3,308 ng/L; DF= 22-67% in northern CA compared to Conc.=21-12,700 ng/L; DF= 22-67% in southern CA; Table 3-15). The difference could be related to many factors including usage (more agriculture) and climate.

One of the most important factors that is expected to be directly related to concentration found in water bodies is imidacloprid usage. Therefore, monitored concentrations were displayed graphically with reported usage data for the same period. Three examples of such graphs are included: the 1st is for monitoring data/usage for agricultural areas (Figure 3-14); the 2nd is for data/usage for mixed agricultural urban area (Figure 3-15); and 3rd is for an urban area (Figure 3-16).

Figure 3-14 Imidacloprid Usage in Agriculture and Observed Concentrations in Santa Barbra County, California from 2010 to 2013.

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Figure 3-15. Imidacloprid Usage and Observed Concentrations in the Urban Areas of Placer, CA from 2011 to 2015 (Empty Brown Circles Represent lbs a.i. Used in Non-Agricultural Areas).

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Figure 3-16. Mixed Urban and Agricultural usage and observed concentrations of imidacloprid in Imperial County, CA during 2010 to 2015.

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C. Storm and Flood Events

Downloaded USGS data contained monitored concentrations in surface waters for samples taken during significant hydrological events including storms and floods (Table 3-16).

Table 3-16 Summary Statistics for Surface Water Monitoring Data during Storms and Floods No. of No. of Detections (ng/L) LOD (ng/L) Item Sites Samples Min Max Min Max Hydrologic Events: Storms (1999-2008; 2010) Sites Sampled > 10 times 3 52 12.0 3,340 6.8 106 Sites Sampled <10-5 times 3 21 4.0 788 6.8 106 Sites Sampled <5-1 times 12 16 10.0 4,490 6.8 106 Total Number of Detects 18 89 4.0 4,490 Sites Sampled > 10 times 7 100 0.0 0.0 6.8 106 Sites Sampled <10-5 times 19 132 0.0 0.0 5 500 Sites Sampled <5-1 times 105 184 0.0 0.0 NR; 5 NR; 111 Total Number of Non- 131 416 0.0 0.0 Detects Grand Total 149 505 Detection: 18% Hydrologic Events: Floods (2000-2004; 2006; 2008-2009; 2011) Total Number of Detects 1 4 5 60 1,470 6.8 60 Total Number of Non-Detects 32 44 0.0 0.0 NR; 6.8 NR; 106 Grand Total 36 49 Detection: 10% 1All Sites were sampled <5-1 times; LOD= Limit of detection

Storm water was sampled at the same site and/or in the same watershed at 149 sites throughout the country. Sites included streams and others representing storm waters from urban, agricultural and mixed- use areas (Figure 3-17).

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Figure 3-17 Spatial Distribution of Storm Water Monitoring Sites

Concentrations found in storm water ranged from 4 to 4,490 ng/L, with a detection frequency of 18%. Monitored concentrations appear to be episodic, with highs dropping sharply into very low or non- detect concentrations. Observed high concentrations are probably associated with the first storm flush especially if that flush happened just after imidacloprid application in the watershed. Lower concentrations are expected to be associated with the distribution of the amounts of the chemical applied within the application window. Giving the high solubility and low soil sorption of imidacloprid, the mass available to be transported by runoff is expected to be reduced by the competing process of leaching. Figure 3-18 and Figure 3-19 show chemo-graphs for eight monitored storm sites with varied concentration patterns probably a reflection of timing, storm duration, and intensity.

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Figure 3-18. Chemo-graphs of Imidacloprid Concentrations in Storm Waters from Four Sites in AL and NC.

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Figure 3-19 (continued) Chemo-graphs of Imidacloprid Concentrations in Storm Waters from Four Sites in NY and MA.

In another study, water samples were found to contain imidacloprid at concentrations ranging from 13.5 to 1,462 ng/L in surface waters generated by a 2-day storm in four of five creeks entering the sloughs of

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Suisun Marsh in San Francisco Bay area in the first winter storm of 2013/2014 (D. P. Weston et al. 27 2015)26F . Imidacloprid presence in the four creeks was related to pesticide applications in urban and mixed land use areas. Higher concentrations were found in storm water from urban areas as compared with areas with mixed agriculture/urban uses. Imidacloprid was not detected (LOD= 10 ng/L) in one of the creeks originating from dominantly agricultural areas. Non-detection was attributed to sample timing which is six months outside the summer application window for the crop. No data were collected from Suisin slough/marsh.

It was reported that the sampled wet season (November through March) had exceptionally little rainfall as accumulation never exceeded 1 cm in any day of the entire season up until the February storm. Therefore, higher runoff and possibly higher pesticide contamination is expected to occur in the more wet years that is expected to occur in this region of California. Figure 3-20 contains a summary of rainfall that generated sampled storm events and associated concentrations of imidacloprid carried in storm waters of the five steams entering the sloughs of Suisun Marsh.

Figure 3-20 Monitored Concentrations of Imidacloprid in Storm Waters Carried by Five Streams Entering Suisun Marsh in California.

Flood surface water was monitored by the New York Water Science Center (reported in the USGS dataset) in three sites at two or three different dates (Table 3-17). Data suggest that June storms at these sites appear to cause contamination of surface waters with imidacloprid at concentrations ranging from 60 to 1,470 ng/L. No other conclusions may be drawn without further information about the sites and source(s) of imidacloprid.

27 Weston, D.P., D. Chen, and M.J. Lydy. 2015. Stormwater-related transport of the insecticides bifenthrin, fipronil, imidacloprid, and chlorpyrifos into a tidal wetland, San Francisco Bay, California. Science of the Total Environment 527-528: 18-25.

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Table 3-17 Monitoring Data Summary for Two and Three Storm Events Storm date Item 5-Jun-03 12/13-Jun-03 13-Apr-04 Site 1 Detected concentrations @ site 1 1,470 ng/L 1,050 No-detect at Site 2 Detected concentrations @ site 2 Not monitored 64 6.8 ng/L limit Site 3 Detected concentrations @ site 3 Not monitored 60 of detection

4. ECOLOGICAL EFFECTS CHARACTERIZATION

In this screening-level ecological risk assessment, the effects characterization describes the types of effects imidacloprid can produce in aquatic organisms. This characterization is based on toxicity studies (registrant-submitted studies and open literature) that describe acute and chronic effects of imidacloprid on aquatic animals and plants under controlled exposures in the laboratory. Registrant- submitted studies are generally conducted under Good Laboratory Practice (GLP) guidelines with the full complement of documentation and raw data. Open literature studies are published in the peer- reviewed scientific literature and contain varying degrees of documentation and quality. Open literature studies on the effects of imidacloprid on aquatic organisms were identified using the USEPA ECOTOX database (last updated in April 2015). The relevance of the open literature data to this assessment was determined based primarily on the consistency of reported endpoints with the Agency’s assessment and measurement endpoints (e.g., effects on survival, growth, reproduction, and development; See Section 2.5). Furthermore, key study design elements were also considered in determining data relevance (e.g., 1 to 4-day exposure duration for acute studies, presence of controls, single chemical exposure, etc.). Once relevant open literature data were identified, they were then compared to the most sensitive registrant-submitted endpoints within each taxonomic group. If the open literature endpoints were lower than the registrant-submitted study endpoints for a particular taxonomic group, the open literature studies reporting the lowest endpoints were reviewed for data 28 reliability according to OPP Open Literature Review Guidance. 27F

While the lowest relevant and reliable endpoints available were selected for estimating risks of imidacloprid to aquatic organisms, it should be recognized that the toxicity test data reported in this section represents a small fraction of species of aquatic organisms in the United States. For example, only a few surrogate species of freshwater fish are used to represent all 2000+ freshwater fish in the United States. Similarly, relatively few species are used to represent the many thousands of freshwater invertebrates in the U.S.

The Agency also recognizes that a significant body of toxicity information is available for imidacloprid based on exposures occurring in the field (e.g., field mesocosm studies) in addition to those involving exposure to invertebrate communities. These higher tier ecological effects studies are not considered as part of this screening-level effects characterization. However, conclusions from various published reviews of the higher tier aquatic effects studies will be considered as part of the Risk Description.

28 https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/guidance-identifying-selecting-and-evaluating-open 66

Formal review of the higher tier studies will be considered if future refinements are required of this screening-level aquatic risk assessment. 4.1. Effects on Fish and Aquatic Phase Amphibians

4.1.1. Acute Toxicity Studies

On an acute exposure basis, imidacloprid is classified as “practically non-toxic” to freshwater and saltwater fish, with acute LC50 values approaching or exceeding 100 mg a.i./L for rainbow trout, bluegill sunfish and sheepshead minnow (Table 4-1). Sublethal effects on fish, including abnormal swimming, and discoloration occurred as low as 42 mg a.i./L. Acute toxicity data were not submitted on the effects of typical end use products (TEPs) on fish; however, such data would not typically be required given the use patterns of imidacloprid (i.e., no direct aquatic use). Given the low acute toxicity of the TGAI to fish, lack of information on the TEP is not considered a major source of uncertainty in this assessment.

Based on the ECOTOX database, no acute toxicity data were identified from the open literature for freshwater and saltwater fish that: 1) established a lower acute toxicity value, 2) reflected measures of effect that were consistent with the Agency assessment endpoints; and 3) were considered acceptable for quantitative use in risk assessment (see Appendix C). One supplemental (qualitative) study was identified that examined the acute toxicity of imidacloprid to amphibians with a relevant apical endpoint (survival; Perez-Iglesias et al., 2010). In this study, imidacloprid was slightly toxic to larvae of the

Montevideo tree frog (96-h LC50 of 52.6 mg a.i./L). For this risk assessment, an acute LC50 value of 229 mg a.i./L (MRID 42055316) is used for acute risk estimation (i.e., acute RQ calculation) for freshwater fish and aquatic-phase amphibians. An acute LC50 value of 163 mg a.i./L is used for acute risk estimation for saltwater fish.

Table 4-1. Acute and Chronic Effects of Imidacloprid on Fish Species Toxicity Value MRID # Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) 2 in mg a.i./L (Author, Date) (Comment) Freshwater Fish and Aquatic-Phase Amphibians1 Acceptable Bluegill sunfish, LC50 >105 42055314 (Practically non-toxic; Lepomis macrochirus (Acute, 96-h) (NA) abnormal behavior > 42 (TGAI, 97.4%) mg ai/L) Acceptable Rainbow trout, LC50 229 42055316 (Practically non-toxic; Oncorhynchus mykiss (Acute, 96-h) (120 – 309) irregular swimming > (TGAI, 95.3%) 89 mg ai/L) Acceptable LC50 >83 (TGAI, 97.4%) 42055315 (n.d.; erratic swimming (Acute, 96-h) (NA) > 64 mg ai/L)4 NOAEC 9.0 Rainbow trout, 49602703 Oncorhynchus mykiss LOAEC 26.9 Acceptable

(TGAI, 98.2%) (Chronic, 91-d, ELS) (timing of hatch & swim-up) (TGAI, 95%) NOAEC <1.2 42055320 Supplemental-

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Species Toxicity Value MRID # Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) 2 in mg a.i./L (Author, Date) (Comment) Qualitative 3 LOAEC 1.2 (Chronic, 98-d, ELS) (fry survival, weight) Supplemental / Montevideo Tree Frog LC50 Perez-Iglesias 52.6 Qualitative (Hypsiboas pulchellus) (Acute, 96-h) et al, 2010) (slightly toxic) Saltwater Fish Acceptable Sheepshead minnow, LC50 163 42055318 (Practically non-toxic; Cyprinodon variegatus (Acute, 96-h) (126-235) abnormal coloration & (TGAI, 96.2%) lethargy > 105 mg ai/L) NOAEC 6.42 --- Estimated using ACR5 Values in bold are used for risk estimation. CI = confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product; n.d.=not determined. 1 In absence of data, fish are used as a surrogate for aquatic-phase amphibians. 2 95% confidence intervals where available 3 Study originally classified as invalid due to lack of raw data reporting, upgraded to supplemental in addendum but potential solvent effects occurred in this study. 4 Acute toxicity classification not determined since the toxicity endpoint was non-definitive. 5 Calculated by dividing the acute LC50 of 163 mg ai/L (sheepshead minnow) by an ACR of 25.4

4.1.2. Chronic Toxicity Studies

Two studies were submitted on the chronic effects of imidacloprid to freshwater fish, both with rainbow trout (Table 4-1). The first study (MRID 42055320) identified statistically significant (p<0.05) reductions in fry survival and weight relative to the solvent control in the lowest test concentration (1.2 mg a.i./L). In this study, fish in the solvent control displayed significantly greater survival and growth compared to fish in the negative control. Notably, effects of imidacloprid on fry survival were not consistent with increasing treatment concentrations. Relative to the solvent control, no statistically-significant effects were observed in fry survival at 2.3 and 9.8 mg a.i./L (survival was > 90% in these treatments), while statistically-significant effects were observed at 1.2, 4.9 and 19 mg a.i./L (75% to 85% survival). Reductions in fry weight (10%) were also not statistically significant at 2.0 mg a.i./L despite being significantly reduced at 1.2 mg a.i./L (13%) relative to the solvent control. Given the uncertainties in this study associated with the possible effect of the solvent on test organisms, the lack of a definitive NOAEC, and the inconsistencies in the dose-response relationships, this test is classified as supplemental-qualitative.

In the second chronic test with rainbow trout, the effects of imidacloprid (0, 0.01, 0.31, 0.98, 3.1, 9.0, and 26.9 mg a.i./L) were evaluated on multiple endpoints over the course of a 91-d exposure period. Hatching success, fry survival, fry weight and length were not statistically different relative to negative controls at any treatment level (no solvent was used in this study). However, it was evident that the % hatch and % of fry reaching the swim-up stage was significantly greater in the highest treatment (26.9 mg a.i./L) over the course of hatching and larval development period relative to control fish. The timing of hatch or swim-up was not affected in any other treatment relative to controls. At the highest treatment, swim-up began on day 40, which was 4 days earlier than controls. After swim-up, the

68 percent of fry reaching the swim-up stage was significantly higher over multiple days. The biological significance of this decreased hatching and development time is not clear because fry survival and growth were not significantly affected relative to controls by the end of the 91-d exposure. However, alterations in the timing of hatching and fry swim-up could adversely affect the ecological fitness of fry populations, if such alterations resulted in asynchronous development relative to important environmental (e.g., temperature) and ecological cues (e.g., food availability, predation).

No relevant chronic toxicity data with freshwater fish or aquatic-phase amphibians were identified from the open literature that: 1) established a lower chronic toxicity value, 2) reflected measures of effect that were consistent with the Agency assessment endpoints; and 3) were considered acceptable for quantitative use in risk assessment. Therefore, a chronic NOAEC of 9.0 mg a.i./L is used for risk estimation with freshwater fish and aquatic-phase amphibians.

For saltwater fish, no chronic toxicity data were submitted by the registrant nor were relevant chronic data identified in the open literature. Therefore, an acute-to-chronic ratio (ACR) of 25.4 was used to estimate a chronic NOAEC of 6.42 mg a.i./L saltwater fish based on the acute LC50 of 163 mg a.i./L for sheepshead minnow (Table 4-1). This ACR was derived using the ratio of acute LC50 of 229 mg a.i./L to the chronic NOAEC of 9.0 mg a.i./L for rainbow trout.

4.2. Toxicity to Aquatic Invertebrates

A relatively large body of scientific literature exists on the toxicity of imidacloprid to aquatic invertebrates. Numerous reviews of these data have recently been published, including: Anderson et al. (2015), EFSA (2015), BCS (2016); Morrissey et al. (2015), PMRA (2016), Pisa et al. (2015), and Smit et al. (2015). One common conclusion from these reviews is the relatively high sensitivity of aquatic insect species compared to other classes of arthropods or other phyla. This finding is not surprising given that the target species of imidacloprid are terrestrial insects. Part of the high sensitivity of insects to imidacloprid may result from its interaction with the nicotinic acetylcholine receptors which vary in composition among various taxa (Ihara et al., 2007; Lalone et al., 2016). Another common theme from several of these reviews is that immobilization and ataxia of test organisms is often seen to occur at concentrations of 1-2 orders of magnitude lower than lethality. Consistent with the Agency’s assessment endpoints, such severe impacts on organism mobility are considered ecologically relevant and appropriate for risk assessment purposes since organisms cannot feed, swim, or avoid predation.

The following discussion of imidacloprid aquatic invertebrate toxicity data first focuses on non-insect taxa (e.g., primarily crustaceans) and then considers aquatic insects (e.g., Empheroptera, Trichoptera, Diptera, etc.). All registrant-submitted studies (acceptable or supplemental) are summarized here regardless if they produced the most sensitive endpoint for that species. For studies identified in the open literature, only those which produced the most sensitive endpoint for a given species and are classified as “quantitative” or “qualitative” are summarized in this section. See Appendix C for the full complement of relevant studies identified from the ECOTOX database.

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4.2.1. Acute Toxicity to Non-Insect Taxa

Relevant acute toxicity data on the effects of imidacloprid to non-insect aquatic invertebrates for 15 freshwater species distributed among various arthropod classes and other phyla (Table 4-2). A summary of these data by broad taxonomic group is provided below.

Branchiopoda. The Branchiopoda (water fleas) are the most common taxonomic group tested (6 species), followed by Malacostraca (amphipods, isopods with 4 species) and Ostrocoda (seed shrimp with 3 species). Imidacloprid (TGAI or TEP) was generally less toxic to water fleas compared to the other non-insect taxa tested. With two exceptions, the acute LC50 or EC50 values were approximately 5,000 µg ai/L or greater for water fleas. Imidacloprid was much more acutely toxic to Chydorus sphaericus (48-h

EC50 = 832 µg ai/L) and Ceriodaphnia dubia (48-h LC50 = 2.1 µg ai/L). The reason for the much greater sensitivity of these two species of water fleas to imidacloprid is not clear, although C. dubia is a much smaller organism compared to D. magna and C. sphaericus. The acute value for C. dubia reported by Chen et al. (2010) reflects an average of 4 separate tests and measured test concentrations. Raw data were obtained from the study authors and this study is classified as “quantitative” (acceptable for quantitative use in risk assessment). Notably, imidacloprid is classified as slightly to practically non-toxic on an acute exposure basis to OPP’s standard freshwater invertebrate test species (D. magna). It is widely recognized in the published literature that D. magna is not a suitable as a surrogate species for assessing the effects of imidacloprid on freshwater invertebrate communities as a whole.

Malacostraca. The amphipod and isopod representatives of Malacostraca appear to be the next most sensitive non-insect class of arthropods to imidacloprid, with acute LC50 or EC50 values ranging from 17 to 74 µg ai/L (Table 4-2). The registrant-submitted study for Hyalella azteca (MRID 42256303;

Acceptable) produced an acute LC50 value of 56 µg ai/L which is three orders of magnitude lower than that submitted for D. magna (MRID 42055317). The acute LC50 value of 17.4 µg ai/L for H. azteca identified from the open literature (Stoughton et al. 2008; Qualitative) is within a factor of three from that obtained with the registrant-submitted study (56 µg ai/L).

Ostracoda. Among non-insect arthropods tested, imidacloprid appears to be most toxic to ostracods

(seed shrimp) with acute EC50 values ranging from 1.0 to 3.0 µg ai/L for three species (Sanchez-Bayo et al., 2006; Qualitative). Ostracods are widely distributed in freshwater and saltwater ecosystems, are considered important components of the aquatic food web, and have been suggested as sensitive bioindicators of anthropogenic stressors, including pesticide exposure (Ruiz et al., 2013).

Other Phyla. Lastly, two tests of non-insect aquatic species were identified for two other phyla (Nemata and Annelida. Table 4-2). Acute toxicity values range from 6.2 µg ai/L (the worm, Lumbriculus variegatus; Alexander et al., 2007; qualitative) to 1,580 µg ai/L (the parasitic nematode, Agamermis unka; Choo et al., 1998; qualitative).

TGAI vs. TEP. Regarding the differential toxicity of TGAI and TEP, the available data summarized in Table 4-2 do not suggest any obvious trend in the toxicity of formulations relative to the active ingredient; however, comparisons were not possible within the same species.

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Table 4-2. Most Sensitive Acute Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid (and Selected Metabolites on Non-Insect, Freshwater Invertebrates Species Endpoint Toxicity Value MRID / Citation Study Classification/ (% a.i.) (Duration) (C.L.) in µg a.i/L 1 (Source) (Comment) Branchiopoda (Water fleas) Water flea, EC50 85,200 42055317 Acceptable Daphnia magna (48-h) (71,000-113,000) (Reg. Sub.) (Slightly toxic) (TGAI, 95.4%) Water flea, Sanchez-Bayo Qualitative EC50, immobility 6,029 Daphnia magna et al., 2006 (Moderately toxic; (48-h) (332-109,433) (TGAI, 95.5%) (Open Lit.) normal light conditions) Water flea, Hayasaka EC50, immobility 36,872 Qualitative Daphnia pulex et al., 2012 (48-h) (28,399-48,106) (Slightly toxic) (TEP, 20%) (Open Lit.) Water flea, Hayasaka EC50, immobility 45,721 Qualitative Moina macroscopa et al., 2012 (48-h) (34,378-62,218) (Slightly toxic) (TEP, 20%) (Open Lit.) Water flea, Sanchez-Bayo Qualitative EC50, immobility 832 Chydorus sphaericus et al., 2006 (highly toxic; dark (48-h) (274-2,522) (TGAI, 99.5%) (Open Lit.) conditions) Water flea, Quantitative LC50 2.1 Chen et al., 2010 Ceriodaphnia dubia (Very highly toxic) (48-h) (1.1 – 2.7) (Open Lit.) (TEP, 42.8%) Water flea, Hayasaka et al., EC50, immobility 5,553 Qualitative Ceriodaphnia reticulata 2012 (48-h) (4,213-7,388) (Moderately toxic) (TEP, 20%) (Open Lit.) Ostracoda (Ostracods) Seed shrimp, Sanchez-Bayo Qualitative EC50, immobility 3.0 Cypridopsis vidua et al., 2006 (Very highly toxic; (48-h) (0.5-15) (TGAI, 99.5%) (Open Lit.) normal light conditions) Seed shrimp, Sanchez-Bayo Qualitative EC50, immobility 1.0 Cypretta seurati et al., 2006 (Very highly toxic; dark (48-h) (0.4-2) (TGAI, 99.5%) (Open Lit.) conditions) Seed shrimp, Sanchez-Bayo Qualitative EC50, immobility 3.0 Ilyocypris dentifera et al., 2006 (Very highly toxic; (48-h) (1-11) (TGAI, 99.5%) (Open Lit.) normal light conditions) Malacostraca (Amphipods, Isopods) Amphipod, LC50 56 42256303 Acceptable Hyalella azteca (96-h) (34 - 99) (Reg. Sub.) (Very highly toxic) (TGAI, %NR) Amphipod, LC50 17.4 Stoughton et al. Qualitative Hyalella azteca (96-h) (13.3-22.8) 2008 (Open Lit.) (Very highly toxic) (TEP, 24%) Amphipod, Van den Brink et Quantitative EC50, immobility 47.6 Gammarus pulex al., 2016 (Very highly toxic; Fall- (96-h) (28.6-79.2) 2 (TEP, 70%.) (Open Lit.) collected organisms) Amphipod, EC50, immobility 14.2 Boettger et al., Qualitative Gammarus roseli (96-h) (6.4-31.2) 2012 (Open Lit.) (Very highly toxic) (TEP, 20%)

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Species Endpoint Toxicity Value MRID / Citation Study Classification/ (% a.i.) (Duration) (C.L.) in µg a.i/L 1 (Source) (Comment) Isopod, 77 Van den Brink et Quantitative EC50, immobility Asellus aquaticus (56-107) 2 al., 2016 (Very highly toxic; Fall- (96-h) (TEP, 70%.) (Open Lit.) collected organisms) Other Taxa Parasitic Nematode, LC50 1,580 Choo et al., 1998 Qualitative Agamermis unka (24-h) (1,260-1,980) (Open Lit.) (Moderately toxic) (TGAI, 97%) Oligochaete worm, Alexander et al., EC50, immobility 6.2 Qualitative Lumbriculus variegatus 2007 (96-h) (±1.4) 3 (Very highly toxic) (TEP, 24%) (Open Lit.) CI = 95% confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product; n.d.=not determined. 1 Units are in µg ai/L unless otherwise specified. 2 Toxicity endpoints recalculated using raw data and USEPA statistical methods. 3 Standard error from multiple tests. 4 Acute toxicity classification not determined since the toxicity endpoint was non-definitive.

4.2.2. Acute Toxicity to Insect Taxa

Aquatic insects are widely reported to be among the most sensitive aquatic invertebrate taxa to imidacloprid (e.g., Anderson et al., 2015; EFSA, 2015; McGee et al., 2016; Morrissey et al., 2015; PMRA, 2016; Pisa et al., 2015; and Smit et al., 2015). The acute toxicity data compiled in this screening-level effects assessment support this conclusion, as shown in Figure 4-1.

100,000 85,200 45,721 36,872 10,000 6,029 5,553

1,000

(ppb) 832 50 236 77 orEC 100 51 56 69 50 48 44 43 17 20 17 10 14 7 6.2 4.2

AcuteLC 2.7 3 3 2.1 1.7 1.38 1 0.77 1 0.65

0

Figure 4-1. Acute Toxicity of Imidacloprid to Freshwater Invertebrates (most sensitive value for each species; open symbols = open literature; solid symbols = registrant data; solid arrow = endpoint used for risk estimation).

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Diptera. Among tested aquatic insect orders, Diptera (true flies) contained qualitative or quantitative data for the most species (five; Table 4-3). For parent imidacloprid, acute LC50 or EC50 values varied from a low of 2.7 µg ai/l for the midge, C. dilutus (LeBlanc et al. 2012; qualitative) to 236 µg ai/L for another species of midge, Chaoborus obscuripes (Roessink et al., 2013; quantitative). The registrant-submitted acute study for C. dilutus (MRID 42256304; acceptable) resulted in a 48-h LC50 of 68.9 µg ai/L which is one order of magnitude greater than the 96-h LC50 reported by LeBlanc et al. 2012). Stoughton et al.

(2008; qualitative) report a 96-h LC50 for C. dilutus (formerly C. tentans) of 5.8 µg ai/L for TGAI and 5.4 µg ai/L for a TEP; (Table C-1, Appendix C). The less sensitive acute toxicity value reported from the registrant-submitted study may reflect, in part, its shorter exposure duration (48 hours) vs. that of the aforementioned open literature studies (96 hours). As seen with the H. azteca (Table 4-2), the major guanidine and urea degradates of imidacloprid are orders of magnitude less toxic than the parent compound to the C. dilutus.

Table 4-3. Most Sensitive Acute Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid (and Selected Metabolites) on Freshwater Dipteran Insects Species Toxicity Value MRID/Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Midge, Acceptable Chironomus dilutus LC50 68.9 42256304 (chronic results (TGAI, 95%) (48-h) (49.3 – 98.5) (Reg. Sub.) invalid) (Very highly toxic)

Guanidine degradate LC50 43946602 >82,800 Supplemental 2 (97%) (96-h) (Reg. Sub.)

LC50 43946604 Acceptable >100,000 Urea degradate (96-h) (Reg. Sub.) (Practically non-toxic) (99%) 44558901 2 LC50 In Review 6-CNA - degradate >1,000 (Reg. Sub.) (96-h) (97%) Midge, LeBlanc et al., LC50 2.7 Qualitative Chironomus dilutus 2012 (96-h) (1.6-3.6) (Very highly toxic) (TEP, 24%) (Open Lit.) Azevedo- Midge, LC50 19.9 Pereira et al., Qualitative Chironomus riparius (48-h) (14.6-27.2) 2011 (Very highly toxic) (TEP, 20%) (Open Lit.) Midge, Roessink et al., Quantitative EC50, immobility 236 Chaoborus obscuripes 2013 (Highly toxic; summer (96-h) (182-307) 1 (TEP, 20%) (Open Lit.) collected organisms) Yellow fever mosquito, Song et al., LC50 44 Qualitative Aedes aegypti 1997 (Open (48-h) (41-47) (Very highly toxic) (TGAI, >95%) Lit.)

Blackfly, LC50 6.8 Overmyer et Qualitative Simulium vittatum (48-h) (6.0-7.4) al., 2005 (Very highly toxic) CI = 95% confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product; n.d.=not determined. 1 Toxicity endpoints recalculated using raw data and USEPA statistical methods. 2 Acute toxicity classification not determined since the toxicity endpoint was non-definitive.

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Ephemeroptera. As a taxonomic group, Ephemeroptera (mayflies) appear to be among the most sensitive taxa to imidacloprid (Table 4-4). The most sensitive 96-h EC50 values (immobilization) varied from 0.65 to 1.39 µg ai/L for three species tested. The most sensitive acute value considered acceptable for quantitative use in risk assessment is 0.77 µg ai/L for the mayfly, Cloeon dipterum (Roessink et al., 2013; quantitative). A slightly lower value (0.65 µg ai/L) was available from Alexander et al. (2007), however, raw data were not available from the study author to independently evaluate the dose- response relationship. Nonetheless, Alexander et al. (2007) indicated in their study that they repeated their acute study several times to confirm the low toxicity value for their mayfly. Thus, the low acute toxicity value for C. dipterum does not appear unique in representing the sensitivity of mayflies to imidacloprid.

Table 4-4. Most Sensitive Acute Toxicity Values on the Effects of Imidacloprid on Ephemeropteran Insects (Mayflies) Species Toxicity Value MRID/Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Quantitative Mayfly, Roessink et al., EC50, immobility 0.77 (Very highly toxic; Cloeon dipterum 2013 (96-h) (0.17-1.65) 1 summer collected (TEP, 20%) (Open Lit.) organisms) Quantitative Mayfly, Roessink et al., EC50, immobility 1.4 (Very highly toxic; Caenis horaria 2013 (96-h) (0.7-2.1) 1 summer collected (TEP, 20%) (Open Lit.) organisms) Mayfly, Alexander et LC50 0.65 Qualitative Epeorus longimanus al., 2007 (96-h) (±0.15) (Very highly toxic) (TEP, 24%) (Open Lit.) CI = 95% confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product; n.d.=not determined. 1 Toxicity endpoints recalculated using raw data and USEPA statistical methods.

Two attributes of the mayfly data reported by Roessink et al. (2013) and Van den Brink et al. (2016) deserve additional discussion. First, it is evident from their data that the effects of imidacloprid (and other neonicotinoids) on mayfly immobilization occur at substantially lower levels than lethality.

Specifically, LC50 values ranged from 6.7 to 154 µg ai/L for C. dipterum and C. horaria whereas EC50 values varied from 0.77 to 32 µg ai/L for these same species (Figure 4-2). This finding is not surprising given the mode of action of imidacloprid and its effect on the nervous system. As previously discussed, immobilization is considered an ecologically relevant apical endpoint for characterizing the acute effects of pesticides, especially neurotoxic insecticides, on aquatic organisms. Second, the season of collection and testing appears to influence mayfly sensitivity, with summer-collected mayflies appearing more sensitive than mayflies collected and tested during other seasons (Figure 4-2). The authors noted this seasonally-dependent sensitivity also occurred with other neonicotinoids (thiamethoxam, thiacloprid) and that organism size and test temperature did not fully explain the differences in sensitivity. They also report similar seasonal differences in acute sensitivity for other insect and non-insect aquatic species.

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Figure 4-2. Acute Toxicity of Imidacloprid to Mayflies as a Function of Endpoint (EC50, LC50) and Season (Source: Van den Brink et al., 2016)

Other Insect Taxa. Acute toxicity data are available for three other insect orders (Heteroptera, Megaloptera and Trichoptera (Table 4-5). Of these three orders, Trichoptera (caddisflies) appear most acutely sensitive to imidacloprid, with acute EC50 values ranging from 1.7 µg ai/L (Roessink et al., 2013; quantitative) to 4.2 µg ai/L (Yokoyama et al., 2009; qualitative). Acute sensitivity of species in the other two insect orders varied from 17 to 50.6 µg ai/L.

Table 4-5. Most Sensitive Acute Toxicity Values on the Effects of Imidacloprid on Other Aquatic Insect Taxa Species Toxicity Value MRID/Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Heteroptera: Quantitative Roessink et al., Water bugs, EC50, immobility 42.9 (Very highly toxic; 2013 Plea minutissima (96-h) (34.9-52.7) 1 summer collected (Open Lit.) (TEP, 20%) organisms) Heteroptera: Roessink et al., Backswimmer, EC50, immobility 17.0 Quantitative 2013 Notonecta sp. (96-h) (8.6-29.6) 1 (Very highly toxic; (Open Lit.) (TEP, 20%) Megaloptera: Alderfly, Roessink et al., EC50, immobility 50.6 Quantitative Sialis lutaria 2013 (96-h) (30.9-82.8)1 (Very highly toxic; (TEP, 20%) (Open Lit.) Trichoptera: Caddisfly, Yokoyama et Cheumatopsyche EC50, immobility 4.2 Qualitative al., 2009 brevilineata (48-h) (3.8-4.5) (Very highly toxic) (Open Lit.) (TGAI, 98%) Trichoptera: Caddisfly Roessink et al., EC50, immobility 1.7 Quantitative family, Limnephilidae 2013 (96-h) (0.94-2.9) 1 (Very highly toxic; (TEP, 20%) (Open Lit.) CI = 95% confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product; n.d.=not determined. 1 Toxicity endpoints recalculated using raw data and USEPA statistical methods.

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4.2.3. Acute Toxicity to Saltwater Aquatic Invertebrates

Data on the acute toxicity of imidacloprid on saltwater aquatic invertebrates are far less abundant compared to freshwater species. Two acceptable registrant-submitted studies available for mysid shrimp, one with TGAI (MRID 42055319) and the other with TEP (MRID 42528301; Table 4-6). The acute

LC50 values from these two studies (33 and 36 µg ai/L) were virtually identical, suggesting no effect of the formulation components relative to the TGAI. Acute toxicity data for two other relevant decapod species (grass shrimp, blue crab) were identified from the open literature. A 24-h LC50 of 10 µg ai/l was reported for blue crab larvae (Osterberg et al., 2012; qualitative), while a 96-h LC50 of 309 µg ai/L was reported for grass shrimp (Key et al., 2007; qualitative). Qualitative acute toxicity data were identified for one saltwater insect species (the mosquito, Aedes taeniorhynchus) which is similarly sensitive as blue crab larvae. The eastern oyster and brine shrimp were less sensitive by three orders of magnitude compared to crab and shrimp. The lowest acceptable (quantitative) acute toxicity value of 33 µg ai/L will be used for estimating risks to saltwater aquatic invertebrates.

Table 4-6. Most Sensitive Acute Toxicity Values on the Effects of Imidacloprid on Saltwater Aquatic Invertebrates Species Endpoint Toxicity Value MRID / Citation Study Classification/ (% a.i.) (Duration) (C.L.) in µg a.i/L (Source) (Comment) Malacostacan Decoapods (Shrimp, Crabs) Mysid shrimp, LC50 33 µg a.i/L 42055319 Acceptable Americamysis bahia (96-h) (29 - 39) (Reg. Sub.) (Very highly toxic) (TGAI, 96%) LC50 36 µg a.i/L 42528301 Acceptable (TEP, 23%) (96-h) (31 – 42) (Reg. Sub.) (Very highly toxic)

Grass shrimp, LC50 Qualitative 309 Key et al., 2007 Palaemonetes pugio (96-h) (Highly toxic; larval (274-349) (Open Lit.) (TGAI; 99.5%) stage) Blue crab, LC50 Qualitative 10.0 Osterberg et al., Callinectes sapidus (24-h) (Very highly toxic; larval (6.4-15.8) 2012 (Open Lit.) (TGAI; 99.5%) stage) Diptera (True flies) Mosquito, LC50 13 Song et al. 1997 Qualitative Aedes taeniorhynchus (48-h) (10-16) (Open Lit.) (Very highly toxic) (TGAI, >95%) Other Saltwater Taxa EC50 Eastern Oyster >145,000 42256305 Acceptable (96-h) (TGAI, 96%) Shell deposition (Reg. Sub.) (Practically non-toxic)

Brine Shrimp LC50 361,000 Song et al. 1997 Qualitative Artemia sp. (48-h) (308,000-498,000) (Open Lit.) (Practically non-toxic) (TGAI, >95%) Values in bold are used for risk estimation. CI = 95% confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product.

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4.2.4. Chronic Toxicity to Freshwater Aquatic Invertebrates

Similar patterns in chronic sensitivity of freshwater aquatic invertebrates to imidacloprid (Figure 4-3) are evident as observed with their acute sensitivity (Figure 4-2), with insects (mayflies in particular) being the most sensitive taxonomic group overall. A brief discussion of these data for non-insect and insect taxa is provided below.

10,000

1,800 1,000

149 150 Aquatic Insects 100 (LOAEC)

10 6 6 3 3.4 2.1 1 1 1.33 1.1 1 0.56 0.74

NOAEC or LOAEC LOAEC (ppb)NOAEC or 0.3 (LOAEC) 0.3 0.3 0.10 0.03 0.010 0.01 Branchiopoda Amphipods Diptera Insect Ephemeroptera (water fleas) & Isopods (midge) (other) (mayfly)

Figure 4-3. Most Sensitive Chronic Toxicity Values on the Effects of Imidacloprid on Freshwater Invertebrates (most sensitive value for each species; open symbols = open lit., closed symbols = registrant data; solid arrow = endpoint used for risk estimation).

Non-Insect Taxa. With one exception, the water fleas (Branchiopoda) appear among the least sensitive group of aquatic invertebrates to chronic imidacloprid exposures (Figure 4-3, Table 4-7). The registrant- submitted study for D. magna resulted in a NOAEC of 1,800 µg ai/L based on significant reductions in Daphnia length at 3,600 µg ai/L. For the same species, an open literature study reported significant effects relative to controls following a 7-d exposure and 27-d observation period at the lowest concentration tested (149 µg ai/L; Agatz et al., 2013; qualitative). One uncertainty with this study is that the authors used non-standard exposure duration (7 days) and reduced food rations (lowest food density recommended by OECD) to purportedly improve environmental realism. Greater effects were observed with an even lower food ration; thus there may be an influence of food ration on imidacloprid toxicity even at the lowest OECD recommended level. In contrast to the D. magna results, Chen et al. (2010) report a chronic LOAEC of 0.3 µg ai/L for the water flea, C. dubia. These were the same authors that previously reported the relatively high acute sensitivity of imidacloprid to C. dubia. For two amphipod and one isopod species, 28-d chronic NOAEC values were very similar (1 to 3.4 µg ai/L).

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Table 4-7. Most Sensitive Chronic Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid on Non-Insect, Freshwater Invertebrates Species Toxicity Value MRID / Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Branchiopoda (Water fleas) NOAEC <0.3 Quantitative Water flea, Chen et al., LOAEC 0.3 (mean of 4 tests, Ceriodaphnia dubia 2010 (8-d, LC) (F1 survival, measured (TEP, 42.8%) (Open Lit.) population size concentrations) & growth rate)

Water flea, NOAEC 1,800 42055321 Daphnia magna Acceptable (Reg. Sub.) (TGAI, 96%) LOAEC 3,600 (21-d, LC) (length) NOAEC <149 Qualitative Water flea, Agatz et al., LOAEC 149 (lowest OECD Daphnia magna 2013 (7d exposure + 27d (length) recommended (TGAI, 96%) (Open Lit.) observation) feeding rate) Malacostraca (Amphipods, Isopods) Amphipod, NOAEC 3 Roessink et al., Gammarus pulex 2013 Quantitative (TEP, 20%) LOAEC 10 (Open Lit.) 1 (28-d) NOAEC 1 Isopod, Roessink et al.,

Asellus aquaticus 2013 Quantitative LOAEC 3 (TEP, 20%) (Open Lit.) 1 (28-d) NOAEC 3.4 Amphipod, Staughton et al. Qualitative Hyalella azteca 2008 LOAEC 11.5 (continuous exposure) (TEP, 24%) (Open Lit.) (28-d) 1 Toxicity endpoints recalculated using raw data and USEPA statistical methods.

Dipteran Insects. Chronic NOAEC values were available for 6 species of dipteran insects which varied from 0.3 µg ai/L for the midge, Chaoborus obscuripes (Roessink et al., 2013; quantitative) to 150 µg ai/L for the yellow fever mosquito, Aedes aegypti (Tome et al., 2014; qualitative; Table 4-8). However, most NOAECs were about 2 µg ai/L or less. The desnitro-olefin metabolite of imidacloprid was 2-3 orders of magnitude less chronically toxic to the midge, C. riparius, compared to the parent compound. One uncertainty with the registrant submitted studies with C. riparius (MRIDs 49602708 and 49602718) is that the NOAEC values are based on initial measure concentrations and thus, may overestimate exposure and underestimate chronic toxicity relative to the average concentrations over the entire exposure period.

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Table 4-8. Most Sensitive Chronic Toxicity Values (Registrant and Open Literature) on the Effects of Imidacloprid (and One Metabolite) on Freshwater Insects Species Toxicity Value MRID / Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Diptera (True Flies) NOAEC 0.3 Midge, Roessink et al.,

Chaoborus obscuripes 2013 Quantitative LOAEC 1 (TEP, 20%) (Open Lit.) 2 (28-d) (immobility) NOAEC 2.1 Midge, In Review 49602708 Chironomus riparius LOAEC 3.7 (Initial nominal (Reg. Sub.) (TGAI, 98.4%) (28-d) (emergence, overlying water conc., develop. rate)

NOAEC 7,900 In Review 49602718 (Initial nominal LOAEC 15,800 Reg. Sub.) Desnitro-olefin overlying water conc. (28-d) (develop. rate) degradate (95.3%) NOAEC 0.74 Azevedo- Midge, Qualitative Pereira et al., Chironomus riparius LOAEC 2.15 (3 renewals, sand 2011 (TEP, 20%) (10-d) (growth, substrate) (Open Lit.) locomotion) NOAEC 1.1 Midge, Staughton et al. Qualitative Chironomus dilutus 1 LOAEC 3.5 2008 (continuous exposure) (28-d) (Survival, dry (Open Lit.) weight)

NOAEC 1.33 In Review Midge, 50087901 (initial mean Chironomus riparius (Reg. Sub.) measured overlying (TEP, 19.6%) LOAEC 2.39 water conc. (28-d) (emergence rate)

NOAEC 0.56 In Review Midge, 50087902 (initial mean Chironomus riparius (Reg. Sub.) measured overlying (TEP, 31.0%) LOAEC 1.00 water conc. (28-d) (emergence rate) NOAEC 6 Cranefly, Kreutzweiser et Qualitative

Tipula sp. al., 2007 (single dose, time LOAEC 74 (TEP, 75%) (Open Lit.) weighted avg.) (14-d) (survival) Yellow fever mosquito, NOAEC 150 Tome et al., Aedes aegypti Qualitative 2014 (TEP, 70%) LOAEC 1,500 (4th instar larvae) (Open Lit.) (10-d)

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Species Toxicity Value MRID / Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Ephemeroptera (Mayflies) NOAEC 0.03 Mayfly, Roessink et al., Quantitative

Cloeon dipterum 2013 (Summer collected LOAEC 0.1 (TEP, 20%) (Open Lit.) 2 mayflies) (28-d) (immobility) NOAEC 0.01 µg a.i/L Mayfly, Roessink et al., Quantitative Caenis horaria LOAEC 0.03 µg a.i/L 2013 (Summer collected (TEP, 20%) (28-d) (immobility) (Open Lit.) 2 mayflies)

Other Insect Taxa NOAEC 0.3 Megaloptera: Alderfly, Roessink et al., Quantitative Sialis lutaria 2013 LOAEC 1.0 (TEP, 20%) (Open Lit.) 2 (28-d) (immobility) Heteroptera: NOAEC 1.0 Roessink et al., Water bugs, Quantitative 2013 Plea minutissima LOAEC 3.0 (Open Lit.) 2 (TEP, 20%) (28-d) (immobility) NOAEC 6.0 Plecoptera: Stonefly, Kreutzweiser et Qualitative

Pteronarcys dorsata al., 2007 (single dose, time LOAEC 74 (survival) (TEP, 75%) (Open Lit.) weighted avg.) (14-d) Values in bold are used for risk estimation. CI = 95% confidence interval; TGAI = technical grade active ingredient; TEP = typical end use product. 1 Formerly named C. tentans. 2 Toxicity endpoints recalculated using raw data and USEPA statistical methods.

Ephemeropteran Insects. Consistent with their high acute sensitivity, the mayfly species, C. dipterum and C. horaria were the most chronically sensitive species tested, with chronic NOAEC values for survival and immobilization of 0.03 and 0.01 µg ai/L, respectively (Table 4-8). It is notable that these studies did not measure other endpoints such as growth and reproduction, which conceivably could be more sensitive than survival or immobilization. With the chronic test of C. horaria, the NOAEC of 0.01 µg ai/L reflects 23% immobility and the LOAEC of 0.03 µg ai/L reflects 37% immobility following 28-d exposure (Figure 4-4). For C. dipterum, a second study was conducted by Van den Brink et al. (2016) from which a NOAEC value of 0.3 µg ai/L was determined for mayflies collected and tested in the winter. This pattern of greater sensitivity of mayflies collected and tested in the summer vs. other seasons is consistent with the acute toxicity findings described earlier.

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Figure 4-4. Chronic Toxicity of Imidacloprid to Two Species of Mayflies and Two Seasons (Source: Roessink et al., 2013; Van den Brink et al., 2016)

Other Insects. Chronic toxicity data were available for three other orders of aquatic insects: Megaloptera, Heteroptera and Plecoptera. The most sensitive chronic NOAEC values for these groups of insects (stonefly, water bugs, alderfly) varied from 0.3 to 6 µg ai/L (Table 4-8).

4.2.5. Chronic Toxicity to Saltwater Aquatic Invertebrates

Chronic exposure to imidacloprid resulted in a NOAEC of 0.163 µg ai/L for mysid shrimp and a LOAEC of 0.326 µg ai/L based on significant reductions in length and weight (Table 4-9). One other chronic value was available for the marine snail, Marisa cornuarietis (Sawasdee & Köhler, 2009; qualitative), but it was less sensitive to imidacloprid by 5 orders of magnitude compared to mysid shrimp.

Table 4-9. Summary of Chronic Toxicity Data on the Effects of Imidacloprid on Saltwater Aquatic Invertebrates Species Toxicity Value MRID / Citation Study Classification/ Endpoint (Duration) (% a.i.) (C.L.) in µg a.i/L (Source) (Comment) Mysid shrimp, NOAEC 0.163 µg a.i./L; Americamysis bahia 42055322 Acceptable (TGAI, 96%) LOAEC 0.326 µg a.i./L (Reg. Sub.) (28-d, LC) (length, wt.) NOAEC 50,000 Marine snail, Sawasdee & Marisa cornuarietis LOAEC >50,000 Köhler, 2009 Qualitative (TGAI, N.R.) (14-d, embryo-larval) (survival, hatch, (Open Lit.) growth, dvlpt.

4.3. Degradate Toxicity

As discussed in Section 3.3, imidacloprid can degrade to several products through multiple pathways, the majority of which show minor formation rates ranging from less than 1% - 6% of the applied 81 residues. Two exceptions to this are the guanidine and urea degradates, both of which form in the aqueous photolysis pathway and the former of which may also form in aerobic and anaerobic aquatic metabolism pathways at rates up to 21% of the applied residues.

Two acute toxicity studies are available for the guanidine and urea degradates to the freshwater amphipod Hyalella azteca and are summarized in Table 4-10. For both studies, the toxicity to Hyalella azteca is shown to be at least 3 orders of magnitude less toxic relative to the toxicity of parent imidacloprid alone to this species (acute LC50 values of 56,000 and > 94,200 µg ai/L respectively relative to parent imidacloprid acute LC50 value of 17.4 µg a.i./L, see Table 4-2.). Although degradate toxicity data are only available for one species of aquatic invertebrates, as Table 4-2 indicates, members of the taxonomic class, Malacostraca, which includes Hyalella azteca, are shown to be at least 3 orders of magnitude more sensitive to parent imidacloprid relative to Daphnia magna, which is the standard test species for freshwater aquatic invertebrates for EPA guidelines.

There are no degradate toxicity studies available for estuarine/marine species of aquatic invertebrates. Similarly, although no degradate toxicity studies are available for freshwater fish and estuarine/marine fish, this taxon has been shown to be orders of magnitude less sensitive to imidacloprid relative to aquatic invertebrates. Therefore, the lack of degradate toxicity information for fish is not likely a significant source of uncertainty.

Table 4-10. Summary of available acute degradate toxicity data to freshwater invertebrates. Species Endpoint Toxicity Value MRID / Citation Study Classification/ (% a.i.) (Duration) (C.L.) in µg a.i/L 1 (Source) (Comment)

Guanidine degradate LC50 56,000 43946601 Acceptable (97%) (96-h) (43,000-63,000) (Reg. Sub.) (Slightly toxic)

Urea degradate LC50 43946603 >94,800 Acceptable1 (99%) (96-h) (Reg. Sub.) 1Acute toxicity classification not determined since the toxicity endpoint was non-definitive.

4.4. Reported Wildlife Incidents

The Office of Pesticide Programs (OPP) maintains a database called the Incident Database System (IDS) in which wildlife incidents reported to the Agency from a variety of sources are maintained. Additionally, the Environmental Fate and Effects Division (EFED) within OPP maintains an incident database called the Environmental Information Incident System (EIIS). There is some overlap with the information housed in these databases, but generally a more detailed narrative of an incident is contained in an EIIS report such as magnitude of the number of organisms impacted, location, date, product used, use pattern, whether the use was a registered use, and any confirmatory residue analysis if available. The sources of information for incidents include, registrant reports submitted under the Federal Insecticides, Fungicides, and Rodenticides Act (FIFRA) §6(a)(2) reporting requirement, as well as reports from local, state, national and international level government reports.

It is noted that not all reported incidents are associated with narrative or analytical information that definitively links imidacloprid exposure to a reported wildlife incident. Analytical information can

82 include residue analysis or some other confirmatory measure that is part of the narrative within an incident report. Even in those cases, many incident reports are associated with findings of other pesticides, of which the interactions with imidacloprid in contributing to potentially enhanced toxicity to wildlife are not fully understood. Typically, the reported wildlife incidents serve as a line of evidence in determining the potential effects of imidacloprid, as the reports are useful in understanding how its use may impact wildlife under the actual use conditions. As stated previously, this assessment focuses on aquatic wildlife and therefore only these incidents are discussed.

A review of the incident database yielded 2 wildlife incident reports concerning aquatic organisms (i.e. fish and invertebrates). Both incidents were associated with non-agricultural uses of imidacloprid on turf. One of these incidents was notably a misuse, which in addition to imidacloprid, also contained the pesticides thiophanate-methyl and deltamethrin, the latter of which shows greater toxicity to fish which was the subject of the incident report. These incidents are summarized in Table 4-11.

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Table 4-11. Summary of reported aquatic wildlife incident reports Incident Use Date Product Location Legality Certainty App. Method Comments Record Pattern Application made on lawn which was followed by approximately an inch of rain within the next two days. On the day following the application, about 3000 crawfish died along a half mile stretch in a nearby creek I007892- 07- Merit Registered approximately 5000 feet from the treated lawn and Turf OH Probable Granular 007 1998 0.5 G Use 1000 feet from the storm drain that leads to the creek. The minnows that were also in the creek appeared unaffected. Water samples that were taken two days after the incident showed imidacloprid to be present from levels ranging from 0.17 – 1.3 ppb. No narrative as part of the incident report, but Merit bullhead fish (Ameiurus sp.) were impacted following a Turf 0.5 G runoff event from a nearby golf course. Products used I015047- 08- Unlikely (for Granular (Golf and two NR Misuse were Merit 0.5 G (imidacloprid) as well as thiophanate- 001 2004 imidacloprid) (imidacloprid) Course) other methyl and deltamethrin. No residue analysis as part a.i. of the report, but deltamethrin may have been likely cause. NR: Not reported

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5. RISK CHARACTERIZATION

Risk characterization provides the final step in the risk assessment process. In this step, exposure and effects characterizations are integrated to provide an estimate of risk relative to established levels of concern (LOCs; Section 5.1). The results are then interpreted for the risk manager through a risk description that considers multiple lines of evidences and an overall conclusion (Section 5.2). In addition, the risk description also contains a discussion of relevant sources of uncertainty in the risk assessment and sensitivity of the risk assessment findings to important methodological assumptions.

5.1. Risk Estimation – Integration of Exposure and Effects Data

As discussed in the problem formulation, risk characterization integrates EECs and toxicity estimates and evaluates the likelihood of adverse ecological effects to non-target species. For imidacloprid, a deterministic approach is used to evaluate the likelihood of adverse ecological effects to non-target species. In this approach, RQs are calculated by dividing EECs by the lowest acceptable/quantitative acute and chronic toxicity endpoints for non-target species:

Risk Quotient (RQ) = Exposure Estimate/Toxicity Estimate

For estimating acute RQ values, peak (one-day average) EECs are used. For estimating chronic RQ values, the 21-d average EEC is used for invertebrates and the 60-d average EEC is used for fish. RQs are then compared to LOCs. These LOCs are criteria used to indicate potential risk to non-target organisms and the need to consider regulatory action. Exceeding an LOC is interpreted to mean that the labeled use of the pesticide has the potential to cause adverse effects on non-target organisms. LOCs currently address the following risk presumption categories for aquatic animals:

 acute risk - potential for acute risk to non-target organisms which may warrant regulatory action in addition to restricted use classification,  acute risk, restricted use – potential for acute risk to non-target organisms, but may be mitigated through restricted use classification,  acute risk, listed species – listed species may be potentially affected by use,  chronic risk – potential for chronic risk may warrant regulatory action, listed species may potentially be affected through chronic exposure,

Risk presumptions, along with the calculation of the corresponding RQs and LOCs, are tabulated in Table 5-1.

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Table 5-1. Risk Presumptions for Aquatic Animals Risk Presumption RQ LOC

Acute Risk EEC/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 0.05 Chronic Risk EEC/NOAEC 1

5.1.1. Risks to Fish and Amphibians

Imidacloprid is classified as practically non-toxic to freshwater and saltwater fish on an acute exposure basis. Additionally, in a chronic freshwater fish study conducted with the rainbow trout, imidacloprid did not cause significant adverse effects up to and including 9,020 µg a.i./L which is over two orders of magnitude higher than the highest 60-day average EEC of 13.3 µg a.i./L. As a result, the maximum acute and chronic RQ values for freshwater and saltwater fish are two to three orders of magnitude below the non-listed and listed species LOC values of 0.5 and 0.05, respectively (Table 5-2). These maximum RQ values reflect the crop exposure scenario producing the highest aquatic EECs, inclusive of all use patterns and all methods of application (FLCarrottSTD; combined Soil + Foliar applied). No acute or chronic toxicity data on the effects of imidacloprid to aquatic phase amphibians were available that were considered acceptable for quantitative use in risk assessment. Consideration of the qualitative endpoint identified for the Montevideo Tree Frog (Perez-Iglesias et al., 2010) will be characterized in Section 5.2, Risk Description).

Table 5-2. Maximum Acute and Chronic Risk Quotients for Freshwater and Saltwater Fish 60-day 3 4 Use Crop Peak EEC2 Acute RQ Chronic RQ EEC2 Category Scenario (mg/L) 5 (mg/L) FW SW FW SW 1 - Root FLCarrotSTD and Tuber (Soil + 0.034 0.013 <0.01 <0.01 <0.01 <0.01 Vegetables Foliar)1 1 One soil application of 0.37 lbs a.i/A followed by 3 foliar applications at 0.04 lbs a.i/A each with 5-day interval. 2 EECs reflect parent imidacloprid alone 3 Acute RQ values for freshwater and saltwater fish are based on the peak EEC / LC50 values of 229 mg a.i./L (bluegill sunfish) and 163 mg a.i./L (sheepshead minnow), respectively. 4 Chronic RQ values for freshwater and saltwater fish are based on the 60-d average EEC / NOAEC values of 9.0 mg a.i./L (rainbow trout) and 6.42 mg a.i./L (sheepshead minnow, estimated using an acute-to-chronic ratio), respectively.

5.1.2. Risks to Aquatic Invertebrates

Imidacloprid is classified as very highly toxic to both freshwater and saltwater invertebrates on an acute exposure basis. Acute and chronic risk estimation for freshwater aquatic invertebrates are based on the use-specific EECs and acute and chronic toxicity endpoints of 0.77 µg a.i./L (mayfly, C. dipterum) and 0.01 µg a.i./L (mayfly, C. horaria), respectively (see Section 4.2 for additional description of these endpoints). Since the aquatic EECs vary according to the application method, risk estimation is

86 presented below separately for the 4 types of application methods modeled in this assessment:

 Soil application;  Foliar spray application;  Seed treatment; and  Combined application methods.

A. Soil Applications

Acute and chronic RQs for freshwater and saltwater aquatic invertebrates associated with the assessed soil applications of imidacloprid are presented in Table 5-3. For each crop group and unique application method (e.g., shank injection, chemigation), aquatic EECs were determined for the crop use scenarios that produced the lowest and highest EECs. This approach was also applied for non-crop use patterns. The minimum and maximum RQ values were determined from these EECs in order to provide bounding estimates associated with each crop and non-crop group assessed.

Table 5-3. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Soil Use Patterns of Imidacloprid Peak 21-day 3 4 Crop Scenario1 Acute RQ Chronic RQ Use Category EEC2 EEC2 (Notes) (µg/L) (µg/L) FW SW FW SW CAonion_WirrigSTD 3.46 2.34 4.5 0.10 234 14 (0.50 lbs a.i/A) 3 - Bulb Vegetables GAOnion_WirrigSTD 5.69 3.64 7.4 0.17 364 22 (0.5 lbs a.i/A) Leafy petiole: CARowCropRLF_V2 0.36 0.28 0.46 <0.01 28 1.7 (0.38 lbs a.i/A @ 10 cm depth) 4 - Leafy Vegetables Leafy petiole: CARowCropRLF_V2 2.23 1.69 2.9 0.07 169 10 (0.38 lbs a.i/A @ 0.64 cm depth) Peppers: 8 - Fruiting Vegetables FLpeppersSTD 5.23 3.57 6.8 0.16 357 22 (0.50 lbs a.i/A) FLcucumberSTD (0.38 lb ai/A; Seedling/Soil 0.00 0.00 <0.01 <0.01 <0.01 <0.01 Drench @ 10 cm depth) CAMelonsRLF_V2 (0.38 lbs a.i/A @ 1.27 cm seed 0.23 0.15 0.30 0.01 15 0.9 depth) FLcucumberSTD 9 - Cucurbit (0.38 lbs ai/A @ 1.85 cm seed 0.64 0.40 0.83 0.02 40 2.5 Vegetables depth) FLcucumberSTD (0.38 lbs ai/A @ >2 cm seed 1.33 0.83 1.7 0.04 83 5.1 depth) FLcucumberSTD 3.13 1.94 4.1 0.09 194 12 (0.38 lbs ai/A; drench to 10 cm) FLcucumberSTD 4.51 2.80 5.9 0.14 280 17 (0.38 lbs a.i/A @ 1.27 cm depth)

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Peak 21-day 3 4 Crop Scenario1 Acute RQ Chronic RQ Use Category EEC2 EEC2 (Notes) (µg/L) (µg/L) FW SW FW SW FLcitrusSTD 0.40 0.26 0.51 0.01 26 1.6 (0.5 lbs a.i/A; Drench) 10 - Citrus Fruits FLcitrusSTD 1.01 0.66 1.3 0.03 66 4.0 (0.5 lbs a.i/A; chemigation) Bushberries: ORberriesOP 0.26 0.19 0.34 0.01 19 1.2 (0.50 lbs a.i/A, drench) Grapes: CAgrapes_WirrigSTD; (0.5 lb 0.57 0.38 0.74 0.02 38 2.3 ai/A) Grapes: NYgrapesSTD 1.87 1.29 2.4 0.06 129 7.9 (0.5 lb ai/A) Strawberry: 13 - Berries FLstrawberry_WirrigSTD 2.18 1.59 2.8 0.07 159 9.8 (0.5 lb ai/A; chemigation) Strawberry: CAStrawberry-noplasticRLF_V2; 2.38 1.72 3.1 0.07 172 11 (0.5 lb ai/A; chemigation) Cranberry: ORberriesOP 7.16 5.22 9.3 0.22 522 32 (0.5 lb ai/A; dry field) Cranberry: (Treated bog sites, 0.5 lbs 11.7 6.99 15 0.35 699 43 a.i./A – PFAM) ORfilbertsSTD 0.25 0.18 0.33 0.01 18 1.1 (0.5 lbs a.i/A; drench) 14 - Tree Nuts GApecansSTD 1.32 0.84 1.7 0.04 84 5.1 (0.5 lbs a.i/A; drench) Banana: FLavocadoSTD 0.06 0.04 0.08 <0.01 4.1 0.25 (0.5 lbs a.i/A; soil drench) Banana: CAAvocadoRLF_V2 0.12 0.08 0.16 <0.01 7.8 0.48 (0.5 lbs a.i/A; soil drench) Banana: 23/24 Tropical and FLavocadoSTD 0.15 0.10 0.20 <0.01 10 0.61 subtropical fruits (0.5 lbs a.i/A) Banana: CAAvocadoRLF_V2 0.30 0.19 0.38 0.01 19 1.2 (0.5 lbs a.i/A) Pomegranate: CAAvocadoRLF_V2 0.30 0.20 0.39 0.01 20 1.2 (0.5 lbs a.i/A) Artichoke: CARowCropRLF_V2 0.47 0.37 0.61 <0.01 37 2.3 (chemigation) No Crop Group Artichoke: CARowCropRLF_V2 5.13 3.50 6.7 0.16 350 21 (seeded/soil)

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Peak 21-day 3 4 Crop Scenario1 Acute RQ Chronic RQ Use Category EEC2 EEC2 (Notes) (µg/L) (µg/L) FW SW FW SW Coffee: PRcoffeeSTD 0.00 0.00 <0.01 <0.01 <0.01 <0.01 (0.5 lbs a.i/A; soil injected) Tobacco NCtobaccoSTD 0.36 0.23 0.46 <0.01 23 1.4 (0.5 lbs a.i/A; drench @ 10 cm) Poplar: CAForestryRLF 0.00 0.00 <0.01 <0.01 <0.01 <0.01 (0.5 lbs a.i/A; soil shanked in 20 cm) Poplar: CAForestryRLF 0.48 0.33 0.62 0.01 33 2.0 (0.5 lbs a.i/A; chemigation) Poplar: PAappleSTD_V2 (0.5 lbs a.i/A; 0.63 0.42 0.81 0.02 42 2.6 chemigation) Christmas Trees: ORXmasTreeSTD (0.5 lbs a.i/A; 0.00 0.00 <0.01 <0.01 <0.01 <0.01 shanked in 20 cm) Christmas Trees: ORXmasTreeSTD (0.5 lbs a./A; 0.35 0.26 0.46 <0.01 26 1.6 chemigation) Nurseries: Non-agricultural (0.5 lbs a.i/A; granular/watered 0.68 0.45 0.88 0.02 45 2.7 in, TN) Nurseries: (0.5 lbs a.i/A; granular/watered 3.45 2.26 4.5 0.10 226 14 in, CA) Residential (Perimeter Treatment): 0.390 0.258 0.51 0.01 26 1.6 (0.5 lbs a.i/A, CA) Residential (Perimeter Treatment): 1.81 1.32 2.4 0.05 132 8.1 (0.5 lbs a.i/A, TX) Commercial (Perimeter Treatment): 0.01 0.009 <0.01 <0.01 0.90 0.1 (0.5 lbs a.i/A, CA) Commercial (Perimeter Treatment): 0.200 0.13 0.26 0.01 13 0.8 (0.5 lbs a.i/A, FL) Bolded and shaded cells reflect acute risk to non-listed species LOC (LOC = 0.5) and chronic risk LOC (LOC = 1); Bold and italicized values indicate exceedance of the acute listed species LOC (LOC = 0.05) 1 Unless otherwise noted, scenario applies to entire crop group 2 EECs reflect parent imidacloprid alone 3 / Freshwater (FW) and saltwater (SW) acute RQs based on peak EEC and EC50 LC50 values of 0.77 µg a.i/L and 33 µg a.i/L, respectively. 4 FW and SW chronic RQs based on 21-day EEC and NOAEC values of 0.01 and 0.16 µg a.i/L, respectively

For agricultural soil applications, acute RQ values for freshwater invertebrates vary from <0.01 (coffee, cucurbits) to 15 (cranberries; Table 5-3). All but two of the 31 agricultural use scenarios assessed for soil

89 applications exceed the listed species acute risk LOC of 0.05 for freshwater invertebrates. The low RQ value predicted for coffee results from applications made > 2 cm below the soil surface which results in no contaminated runoff according to exposure modeling. Acute RQ values exceed the non-listed species acute risk LOC of 0.5 in 19/31 (61%) of the scenarios modeled. For saltwater invertebrates, acute RQ values vary from <0.01 (coffee, cucurbits) to 0.35 (cranberries). Acute RQ values for saltwater invertebrates are lower by a factor of 42X since the most sensitive acute toxicity endpoint for saltwater invertebrates is 42X less sensitive than that for freshwater invertebrates, and the same EECs are used to assess risks to both freshwater and saltwater species. Accordingly, acute RQ values for saltwater invertebrates did not exceed the non-listed acute risk LOC of 0.5, but 12 (39%) of the acute RQ values exceed the listed species acute risk LOC of 0.05. Chronic RQs for both freshwater and saltwater invertebrates associated with agricultural uses are much higher than their respective acute RQs, which is due mostly to the much lower chronic toxicity endpoints for these taxa (0.01 and 0.163 µg a.i./L, respectively). Chronic RQ values range from <0.01 (coffee, cucurbits) to 699 (cranberries) for freshwater invertebrates and from <0.01 to 43 for saltwater invertebrates. Nearly all of the soil/agricultural use scenarios result in chronic RQ values which exceed the chronic risk LOC of 1.0 for freshwater and saltwater invertebrates (94% and 81%, respectively).

For non-agricultural use scenarios involving only soil applications, acute RQ values for freshwater invertebrates vary from <0.01 (Christmas & poplar tree) to 4.5 (nursery) while those for saltwater invertebrates vary from <0.01 to 0.1 for the same use scenarios (Table 5-3). Chronic RQ values for non- agricultural soil uses of imidacloprid range from <0.01 to 226 for freshwater invertebrates and from <0.01 to 14 for saltwater invertebrates. Similar to the agricultural soil applications, the RQ values of <0.01 result from applications below 2 cm from the soil surface whereby exposure modeling assumes no runoff or drift.

B. Foliar Applications

For foliar spray applications to agricultural crops, acute RQ values for freshwater aquatic invertebrates vary from 1.6 to 20, both within the citrus crop group (Table 5-4). All 15 foliar use scenarios modeled result in acute RQ values that exceed the non-listed acute risk LOC of 0.5 for freshwater aquatic invertebrates. Acute RQ values for saltwater invertebrates varied from 0.04 to 0.47, with no exceedance of the non-listed acute risk LOC and 9 exceedances of the listed species acute risk LOC. Chronic RQ values for foliar (agricultural) uses range from 82 to 988 for freshwater invertebrates (citrus) and from 5 to 61 for saltwater invertebrates. All of the 15 assessed foliar/agricultural use scenarios result in chronic RQ values which exceed the chronic risk LOC of 1.0 for freshwater and saltwater invertebrates. The higher RQ values estimated for foliar uses relative to soil uses of imidacloprid likely reflect greater inputs from the aquatic ecosystem via spray drift.

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Acute and chronic RQ values associated with non-agricultural/foliar uses of imidacloprid are of a similar order of magnitude as the agricultural uses described previously. Acute RQ values range from 1.7 to 20 for freshwater invertebrates and from 0.04 to 0.47 for saltwater invertebrates (Table 5-4). Chronic RQ values for freshwater and saltwater invertebrates exceed the chronic LOC for all nine non-agricultural scenarios assessed (overall range: 5.9 -1020).

Table 5-4. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Foliar Use Patterns of Imidacloprid Peak 21-day Acute RQ4 Chronic RQ5 Use Category Crop Scenario1,2 EEC3 EEC3

(mg/L) (mg/L) FW SW FW SW CAcitrus_WirrigSTD 1.26 0.82 1.6 0.04 82 5.0 (0.25 lbs a.i/A; 2X; 10d) 10 – Citrus Fruits FLcitrusSTD 15.60 9.88 20 0.47 988 61 (0.25 lbs a.i/A; 2X; 10d) WAorchardsNMC 1.44 0.99 1.9 0.04 99 6.1 (0.1 lbs a.i/A; 5X, 10d) NCorchardsNMC 6.39 4.35 8.3 0.19 435 27 (0.1 lbs a.i/A; 5X, 10d) Pears: 11 - Pome Fruits WAorchardsNMC 1.56 1.08 2.0 0.047 108 6.6 (0.25 lbs a.i/A, 2X, 10d) Pears: NCorchardsNMC 11.10 7.43 14 0.34 743 46 (0.25 lbs a.i/A, 2X, 10d) Cherries CAfruit_WirrigSTD 1.64 1.24 2.1 0.049 124 7.6 (0.1 lbs a.i/A, 5X, 10d) 12 - Stone Fruits Cherries: MICherriesSTD 4.42 3.30 5.7 0.13 330 20 (0.1 lbs a.i/A, 5X, 10d) Bushberry: 13 - Berries ORberriesOP 2.73 1.99 3.5 0.08 199 12 (0.1 lbs a.i/A, 5X, 7d) Bananas: FLcitrusSTD 1.38 0.98 1.8 0.04 98 6.0 (0.1 lbs a.i/A, 5X, 14d) Bananas: CAAvocadoRLF_V2 2.49 1.63 3.2 0.08 163 10 23/24 Tropical and (0.1 lbs a.i/A, 5X, 14d) subtropical fruits (edible and Tropical fruit: inedible peel) FLcitrusSTD 1.32 0.88 1.7 0.04 88 5.4 (0.1 lbs a.i/A, 5X, 14d) Tropical fruit: CAAvocadoRLF_V2 2.61 1.72 3.4 0.08 172 11 (0.1 lbs a.i/A, 5X, 14d) Artichoke: CARowCropRLF_V2 2.23 1.58 2.9 0.07 158 9.7 No Crop Group (0.12 lbs a.i/A, 4X, 14d) Coffee: 11.90 8.08 15 0.36 808 50 PRcoffeeSTD

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Peak 21-day Acute RQ4 Chronic RQ5 Use Category Crop Scenario1,2 EEC3 EEC3

(mg/L) (mg/L) FW SW FW SW (0.10 lbs a.i/A, 5X, 7d)

Christmas Trees: ORXmasTreeSTD 2.48 1.94 3.2 0.08 194 12 (0.10 lbs a.i/A, 5X, 7d) Poplar: CAForestryRLF; 3.94 2.82 5.1 0.12 282 17 (0.10 lbs a.i/A, 5X, 10d) Poplar: PAappleSTD_V2 5.82 3.89 7.6 0.18 389 24 (0.10 lbs a.i/A, 5X, 10d) Nursery: CAnurserySTD_V2 3.59 2.37 4.7 0.11 237 15 (0.40 lbs a.i/A, 1X, NA) Nursery: Non-agricultural Uses TNnurserySTD_V2 15.50 10.20 20 0.47 1020 63 (0.40 lbs a.i/A, 1X, NA) Turf: CATurfRLF 2.07 1.43 2.7 0.06 143 8.8 (0.50 lbs a.i/A, 1X, NA) Turf: FLturfSTD 3.74 2.36 4.9 0.11 236 14 (0.50 lbs a.i/A, 1X, NA) Turf (granular): CATurfRLF 1.34 0.95 1.7 0.04 95 5.9 (0.50 lbs a.i/A, 1X, NA) Turf (granular): FLturfSTD 3.18 2.00 4.1 0.10 200 12 (0.50 lbs a.i/A, 1X, NA) Bolded and shaded cells reflect acute risk to non-listed species LOC (LOC = 0.5) and chronic risk LOC (LOC = 1); Bold and italicized values indicate exceedance of the acute listed species LOC (LOC = 0.05) 1 Unless otherwise noted, scenario applies to entire crop group 2 Presented as single application rate; number of applications; interval (where applicable) 3 EECs reflect parent imidacloprid alone 4 / Freshwater and saltwater acute RQs based on peak EEC and EC50 LC50 values of 0.77 µg a.i/L and 33 µg a.i/L, respectively. 5 Freshwater and saltwater chronic RQs based on 21-day EEC and NOAEC values of 0.01 and 0.16 µg a.i/L, respectively

C. Seed Treatment

For applications of treated seeds, acute RQ values for freshwater aquatic invertebrates vary from <0.01 (legumes, potato) to 1.6 for sugarbeet (Table 5-5). Three seed treatment use scenarios result in exceedances of the non-listed acute risk LOC (0.5) for freshwater invertebrates (sugarbeet, canola and flax/crambe). Acute RQ values for the remaining five scenarios assessed are below the listed species acute risk LOC of 0.05. None of the acute RQ values calculated for saltwater invertebrates exceed the listed or non-listed species acute risk LOC values (RQs ranged from <0.01 to 0.04). Chronic RQ values for applications of treated seed range from <0.01 to 84 for freshwater invertebrates and from <0.01 to 5.1 for saltwater invertebrates. These acute and chronic RQ values tend to be much lower than those presented previously for soil and foliar application of imidacloprid for two primary reasons. First the application rates for several of the seed treatment use scenarios (e.g., cereal grains at 0.023 lb a.i./A) 92 are substantially lower than those for soil or foliar application (maximum rate of 0.5 lb a.i./A). Second, the planting depth of treated seeds greatly affects the runoff loading estimated by exposure modeling. Planting depths of > 2 cm are predicted to generate no contaminated runoff from the treated field (e.g., potato, legumes). Notably, however, the exposure modeling associated with seed treatment application does not account for the potential for deposition of contaminated seed coat-dust onto the treated field. This model limitation is discussed further in Risk Description (Section 5.2).

Table 5-5. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Seed Treatment Use Patterns of Imidacloprid Peak 21-day Acute RQ3 Chronic RQ4 Use Category Crop Scenario1 EEC2 EEC2 (mg/L) (mg/L) FW SW FW SW Potato: 0.00 0.00 <0.01 <0.01 <0.01 <0.01 (0.5 a.i/A) 1 - Root and Tuber Sugarbeet: Vegetables CAsugarbeet_WirrigOP 1.20 0.84 1.6 0.04 84 5.1 (0.43 lbs a.i/A) ILbeansNMC; 6 - Legumes ORsnbeansSTD 0.00 0.00 <0.01 <0.01 <0.01 <0.01 (0.5 lbs a.i/A) KSsorghumSTD 0.01 0.01 0.01 <0.01 0.57 0.03 (0.023 lbs a.i/A) 15 - Cereal Grains TXsorghumOP 0.02 0.01 0.02 <0.01 1.0 0.06 (0.023 lbs a.i/A) Canola: NDcanolaSTD 0.65 0.52 0.85 0.02 52 3.2 (0.082 lbs a.i/A) Flax/crambe: 20 - Oilseed TXwheatOP 0.16 0.11 0.20 <0.01 11 0.67 (0.045 lbs a.i/A) Flax/Crambe CAWheatRLF_V2 1.10 0.71 1.4 <0.01 71 4.4 (0.045 lbs a.i/A) Bolded and shaded cells reflect acute risk to non-listed species LOC (LOC = 0.5) and chronic risk LOC (LOC = 1); Bold and italicized values indicate exceedance of the acute listed species LOC (LOC = 0.05) 1 Unless otherwise noted, scenario applies to entire crop group 2 EECs reflect parent imidacloprid alone 3 / Freshwater and saltwater acute RQs based on peak EEC and EC50 LC50 values of 0.77 µg a.i/L and 33 µg a.i/L, respectively. 4 Freshwater and saltwater chronic RQs based on 21-day EEC and NOAEC values of 0.01 and 0.16 µg a.i/L, respectively

D. Combined Applications

Many labeled agricultural uses of imidacloprid allow for a combination of application methods to be used for a given crop (e.g., seed, soil, foliar). A total of 49 combined application use scenarios were assessed (Table 5-6). For combined agricultural uses, acute RQ values for freshwater aquatic invertebrates exceed the non-listed species acute risk LOC of 0.5 for all 49 scenarios modeled (acute RQ range: 0.66 to 44). Acute RQ values for saltwater invertebrates vary from 0.02 to 1.0, with 1 exceedance of the non-listed LOC and 34 exceedances of the listed species LOC.

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Chronic RQ values for combined agricultural uses range from 39 to 2,130 for freshwater invertebrates and from 2.4 to 131 for saltwater invertebrates. All of the combined use scenarios exceed the chronic risk LOC of 1.0 for both freshwater and saltwater invertebrates.

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Table 5-6. Acute and Chronic Risk Quotients for Freshwater and Saltwater Invertebrates for the Registered Use Patterns Where Combined Application Methods of Imidacloprid Are Permitted Peak 21-day 4 5 Crop Scenario Acute RQ Chronic RQ Use Category Scenario Notes2 EEC3 EEC3 (Application method description)1 (mg/L) (mg/L) FW SW FW SW Potato: FLpotatoNMC 0.63 0.53 0.8 0.02 53 3.2 (Soil-chemigation/foliar) NA; 0.30; 0.20 Potato: CAPotatoRLF_V2 3.96 2.76 5.1 0.12 276 17 (Soil-chemigation/foliar) Tuberous/Corm Vegetables: NCSweetPotatoSTD 1.46 0.96 1.9 0.04 96 5.9 (Soil-shanked in 2.54 cm/foliar) NA; 0.37; 0.13 1 – Root and Tuber Vegetables Tuberous/Corm Vegetables: 2.98 2.09 3.9 0.09 209 13 NCSweetPotatoSTD Carrots: FLcarrotSTD 13.30 8.48 17 0.40 848 52 (Seed/Soil at 2.54 cm/Foliar) 0.1; 0.27; 0.13 Carrots: FLcarrotSTD 14.10 9.98 18 0.43 998 61 (Seed/Chemigation/Foliar) Root Vegetables (except sugarbeet) NA; 0.37; 0.13 33.90 21.30 44 1.0 2130 131 FLcarrotSTD Leek: CAonion_WirrigSTD 0.87 0.58 1.1 0.03 58 3.6 (Seed/Soil) 0.18; 0.32; NA Leek: GAOnion_WirrigSTD 8.35 5.56 11 0.25 556 34 (Seed/Soil – GA) 3 – Bulb Vegetables Onion: CAGarlicRLF_V3 0.80 0.53 1.0 0.02 53 3.2 (Seed/Soil) 0.16; 0.34; NA Onion: CAonion_WirrigSTD 7.63 5.08 9.9 0.23 508 31 (Seed/Soil) Leafy Greens: CAlettuceSTD (0.26; NA; 0.24) 4.19 3.04 5.4 0.13 304 19 (Soil (drench)/foliar) Leafy Greens: CAlettuceSTD 4 – Leafy Vegetables (0.26; NA; 0.24) 13.60 9.89 18 0.41 989 61 (Soil/foliar) Watercress: PFAM (TN) (0, 0.26, 0.24) 8.60 1.41 11 0.26 141 8.7 FLcabbageSTD 8.71 6.63 11 0.26 663 41 (Soil/foliar) 5 – Brassica (Cole) Leafy Vegetables NA; 0.26; 0.24 CAColeCropRLF_V2 9.49 6.80 12 0.29 680 42 (Soil/foliar)

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Peak 21-day 4 5 Crop Scenario Acute RQ Chronic RQ Use Category Scenario Notes2 EEC3 EEC3 (Application method description)1 (mg/L) (mg/L) FW SW FW SW Broccoli: CAColeCropRLF_V2 0.18; 0.08; 0.24 7.74 5.44 10 0.23 544 33 (Seed/soil/foliar) Mustard: CAColeCropRLF_V2 0.07; 0.19; 0.24 4.79 3.39 6.2 0.15 339 21 (Seed/soil/foliar) Legumes (except soybean): ORsnbeansSTD 2.95 2.18 3.8 0.09 218 13 (Soil/foliar) NA; 0.37; 0.13 Legumes (except soybean): ILbeansNMC 5.59 4.00 7.3 0.17 400 25 (Soil/foliar) 6 – Legume Vegetables Soybean: MSsoybeanSTD 1.84 1.18 2.4 0.06 118 7.2 (Seed/foliar – early May) 0.21; NA; 0.14 Soybean: MSsoybeanSTD 2.86 2.00 3.7 0.09 200 12 (Seed/foliar – early April) Peppers: FLpeppersSTD 0.046; 0.21; 0.24 6.29 4.71 8.2 0.19 471 29 (Transplants/Soil/Foliar) Fruiting vegetables (except peppers): CAtomato_WirrigSTD 1.61 1.15 2.1 0.049 115 7.1 8 – Fruiting Vegetables (Transplants/Soil/Foliar) 0.036; 0.11; 0.24 Fruiting vegetables (except peppers): FLtomatoSTD 10.30 7.68 13 0.13 768 47 (Transplants/Soil/Foliar – FL) FLcitrusSTD 0.24; 0.26; NA 0.82 0.54 1.1 0.02 54 3.3 (Transplant/Soil) 10 – Citrus Fruits FLcitrusSTD 0.24; NA; 0.26 6.71 4.53 8.7 0.20 453 28 (Transplant/Foliar) WAorchardsNMC 0.98 0.68 1.3 0.03 68 4.1 (Soil-chemigation/foliar) 11 – Pome Fruits NA; 0.20; 0.30 NCappleSTD 5.46 3.73 7.1 0.17 373 23 (Soil-chemigation/Foliar) Apricot, nectarine, peach: CAfruit_WirrigSTD; 1.11 0.81 0.88 0.03 81 5.0 (Soil-chemigation/foliar) NA; 0.20; 0.30 Apricot, nectarine, peach: 12 – Stone Fruits GAPeachesSTD 2.13 1.47 2.8 0.06 147 9.0 (Soil-chemigation/foliar Cherries, plums: CAfruit_WirrigSTD; NA; 0.20; 0.30 1.50 1.01 1.90 0.05 101 6.2 (Soil-chemigation/foliar) 96

Peak 21-day 4 5 Crop Scenario Acute RQ Chronic RQ Use Category Scenario Notes2 EEC3 EEC3 (Application method description)1 (mg/L) (mg/L) FW SW FW SW Cherries, plums: MICherriesSTD 3.10 2.14 1.6 0.09 214 13 (Soil-chemigation/foliar) Bushberry: ORberriesOP NA; 0.20; 0.30 2.46 2.03 3.2 0.07 203 12 Strawberry: CAStrawberry-noplasticRLF_V2 2.56 1.61 3.3 0.08 161 9.9 (Soil-chemigation/foliar) NA; 0.36; 0.14 Strawberry: CAStrawberry-noplasticRLF_V2 3.64 2.47 1.3 0.11 247 15 13 – Berries (Soil-chemigation/foliar) Grapes: CAgrapes_WirrigSTD; 0.69 0.48 0.90 0.02 48 2.9 (Soil/foliar) NA; 0.40; 0.10 Grapes: NYGrapesSTD 2.20 1.78 2.9 0.07 178 11 (Soil/foliar) ORfilbertsSTD 3.60 2.56 4.7 0.11 256 16 (Soil drench/foliar) 14 – Tree Nuts NA; 0.14; 0.36 GAPecansSTD 6.40 4.33 8.3 0.19 433 27 (Soil drench/foliar) ORmintSTD 1.37 0.94 1.8 0.04 94 5.7 (Soil-chemigation/foliar) 19 – Herbs and Spices NA; 0.37; 0.13 ORmintSTD 3.02 2.22 3.9 0.09 222 14 (Soil/foliar) Cotton: CAcotton_WirrigSTD 0.51 0.39 0.66 0.02 39 2.4 (Seed/soil/foliar – CA) 20 - Oilseed 0.095; 0.11; 0.30 Cotton: STXcottonNMC 8.95 6.26 12 0.27 626 38 (Seed/soil/foliar – TX) 23/24 – Tropical and CAfruit_WirrigSTD subtropical fruits NA; 0.20; 0.30 1.61 1.18 2.1 0.05 118 7.2 (Soil-chemigation/foliar) (edible and inedible peel) Hops: ORhopsSTD NA; 0.20; 0.30 0.80 0.55 1.0 0.02 55 3.4 (Soil/Foliar) Tobacco: NCtobaccoSTD NA; 0.22; 0.28 0.88 0.65 1.1 0.03 65 4.0 (Soil drench/foliar – 2 weeks later) No Crop Group Peanuts: NCpeanutSTD 0.14; 0.23; 0.13 2.03 1.41 2.6 0.06 141 8.7 (Seed/soil-chemigation/foliar) Peanuts: NCpeanutSTD NA; 0.37; 0.13 2.18 1.49 2.8 0.07 149 9.1 (Soil-seed depth/foliar)

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Peak 21-day 4 5 Crop Scenario Acute RQ Chronic RQ Use Category Scenario Notes2 EEC3 EEC3 (Application method description)1 (mg/L) (mg/L) FW SW FW SW 1 Unless otherwise noted, scenario applies to entire crop group 2 Presented as application rate (in lbs a.i/A) for seed/seedling treatment; soil treatment; total foliar treatment (where applicable) 3 EECs reflect parent imidacloprid alone 4 / Freshwater and saltwater acute RQs based on peak EEC and EC50 LC50 values of 0.77 µg a.i/L and 33 µg a.i/L, respectively. 5 Freshwater and saltwater chronic RQs based on 21-day EEC and NOAEC values of 0.01 and 0.16 µg a.i/L, respectively 6Bolded and shaded cells reflect acute risk to non-listed species LOC (LOC = 0.5) and chronic risk LOC (LOC = 1); italicized values indicate exceedance of the acute listed species LOC (LOC = 0.05)

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5.2. Risk Description – Interpretation of Direct Effects

In risk description, results from the risk estimation are interpreted and synthesized into overall risk conclusions. This description considers other lines of evidence (e.g., monitoring data, field data, incident reports, etc.) for characterizing ecological risk. In addition, the risk description also contains a discussion of relevant sources of uncertainty in the risk assessment and sensitivity of the risk assessment findings to important methodological assumptions. It also addresses other concerns including risks to threatened and endangered species.

5.2.1. Risks to Fish and Amphibians

Risks based on Modeled Exposures

Imidacloprid is classified as practically non-toxic to freshwater and saltwater fish on an acute exposure basis (LC50 > 100 mg ai/L/L) and the unbounded NOAEC for chronic effects on fish is 9 mg ai/L L (9,000 µg ai/L). Modeled aquatic EECs are several orders of magnitude below acute and chronic toxicity endpoints. Acute and chronic RQ values are similarly two to three orders of magnitude below acute and chronic risk LOCs. Thus, this comparison of model-based exposures with fish acute and chronic toxicity endpoints suggests registered uses of imidacloprid have a low potential for causing direct effects on freshwater and saltwater fish. As indicated below, the potential exists for risks to fish indirectly through reductions in aquatic invertebrates that comprise their prey base.

For aquatic-phase amphibians, acute or chronic toxicity data were not available for imidacloprid that were considered acceptable for quantitative use in risk assessment. One study was identified which provides a 96-h acute LC50 value of 52,600 µg ai/L for the Montevideo tree frog (Perez-Iglesias et al., 2010; qualitative). This acute toxicity endpoint is comparable to that observed for freshwater fish and suggests that aquatic phase amphibians are also relatively insensitive to imidacloprid on an acute exposure basis. While the available data for aquatic-phase amphibians are clearly very limited, other amphibian species would have to be nearly 4 orders of magnitude more sensitive than the Montevideo tree frog to raise risk concerns. Given that vertebrate animals are much less sensitive to imidacloprid compared to most invertebrates, it is considered unlikely that freshwater amphibians would be at risk of direct effects from registered uses of imidacloprid. As indicated with fish, indirect effects on aquatic- phase amphibians through reductions in their invertebrate prey base are considered possible.

Risks based on Monitored Exposures

The review of targeted and non-targeted monitoring data on the concentrations of imidacloprid in surface water reveals that maximum levels detected approximate 10 µg ai/L (Section 3.5). This review encompasses over 7,000 samples distributed across more than 1,400 agricultural, urban and mixed-use sites from 1999-2015. The maximum levels detected are nearly three orders of magnitude below the chronic toxicity endpoint of 9,000 µg ai/L for fish (rainbow trout). While the current surface water monitoring data likely underestimate peak concentration due to low temporal resolution in sampling, it

99 likely provides a more realistic estimate of longer-term average concentrations that are more commensurate with the chronic exposures associated with the fish chronic toxicity study. Therefore, the wide margin of exposure between the chronic toxicity endpoint for fish and the maximum reported concentrations in surface water also suggests that risks of direct effects to fish from registered uses of imidacloprid are unlikely.

Ecological incidents

A review of EPA’s Environmental Information Incident System (EIIS) identified one wildlife incident report involving fish that had some association with imidacloprid (I015047-001). In this incident, bullhead catfish were impacted after a runoff event from a nearby golf course. However, two other active ingredients were applied to the golf course besides imidacloprid and one of these (deltamethrin) is much more toxic to fish compared to imidacloprid. Since a residue analysis was not conducted, there is high uncertainty as to the causal stressor(s) in this incident. Furthermore, this incident is characterized as a “misuse” and therefore, does not reflect a labeled use of imidacloprid. A second incident report (I007892-007) also involved imidacloprid use on turf and a runoff event into a nearby creek soon after application. Extensive mortality of crawfish occurred, but fish were apparently not impacted despite measured concentrations of 0.17 to 1.3 µg ai/L. While the lack of reported ecological incidents does not imply lack of incidences due to underreporting, the limited information currently available on aquatic incidents involving imidacloprid does not suggest that registered uses of imidacloprid are having direct adverse impacts on fish.

5.2.2. Risks to Aquatic Invertebrates

Risks based on Modeled Exposures

Imidacloprid is classified as very highly toxic to both freshwater and saltwater invertebrates on an acute exposure basis. Its acute and chronic toxicity endpoints are 0.77 µg ai/L (EC50) and 0.01 µg ai/L (NOAEC) for the most sensitive aquatic invertebrates tested (mayflies). While the majority of modeled EECs for imidacloprid are in the low µg ai/L range, its very high toxicity to aquatic insects results in the vast majority of modeled imidacloprid use scenarios as having the potential to cause direct effects to sensitive aquatic invertebrates.

Within each type of usage (agricultural, non-agricultural) and application method (soil, foliar, seed treatment, combined), the minimum, maximum and exceedance frequency of acute and chronic LOC values are provided in Table 5-7. Foliar and combined application methods have the greatest frequency of exceeding acute or chronic risk LOCs, with 100% of the modeled scenarios resulting in acute and chronic RQ values above their respective LOC for freshwater invertebrates. Soil application of imidacloprid generally produced lower EECs relative to foliar and combined application methods (Table 5-3) and as a result, both the magnitude and frequency of LOC exceedances are reduced relative to foliar/combined application methods. Exposure modeling for soil application methods indicates less loading to aquatic ecosystem from spray drift relative to foliar/combined methods. Furthermore, no runoff is produced for soil applications that are made > 2 cm below the soil surface. The frequency and

100 magnitude of acute and chronic RQ values are lowest for applications of imidacloprid-treated seeds. This is partly due to lower application rates relative to the other application methods but also due to planting depths that reduce or eliminate contaminated runoff according to exposure modeling.

Table 5-7. Summary of Aquatic Invertebrate Acute and Chronic RQ Values for All Modeled Uses Acute RQ 1 Chronic RQ 1 Appl. Method Use Type (n) RQ Statistic FW SW RQ Statistic FW SW Agricultural Soil (31) min <0.01 <0.01 min <0.01 <0.01 max 15 0.35 max 699 43 RQ>0.5 61% 0% RQ>1 94% 81% RQ>0.05 94% 39% Non-Ag. Soil (11) min <0.01 <0.01 min <0.01 <0.01 max 4.5 0.10 max 226 14 RQ>0.5 55% 0% RQ>1 73% 64% RQ>0.05 73% 18% Agricultural Foliar (16) min 1.6 0.04 min 82 5.0 max 20 0.47 max 988 61 RQ>0.5 100% 0% RQ>1 100% 100% RQ>0.05 100% 60% Non-Ag. Foliar (9) min 1.7 0.04 min 95 5.9 max 20 0.47 max 1020 63 RQ>0.5 100% 0% RQ>1 100% 100% RQ>0.05 100% 89% Agricultural Seed (8) min <0.01 <0.01 min <0.01 <0.01 max 1.6 0.04 max 84 5.1 RQ>0.5 38% 0% RQ>1 50% 38% RQ>0.05 50% 0% Agricultural Combined (48) min 0.66 0.02 min 39 2.4 max 44 1.0 max 2130 131 RQ>0.5 100% 2% RQ>1 100% 100% RQ>0.05 100% 69% 1. RQ values in bold exceed the acute, non-listed or listed species LOC values (0.5 or 0.05, respectively) or the chronic LOC of 1.0

Risks based on Monitored Exposures

Monitoring data provide another useful line of evidence for characterizing risk of registered uses of imidacloprid to aquatic invertebrates. In particular, monitoring data are instructive for placing the modeled EECs in context when recognizing the limitations in the data. Furthermore, monitoring data can be evaluated against existing toxicity endpoints as a way of interpreting potential risk.

As described Section 3.5, an extensive database is available of monitored concentrations of imidacloprid in surface water throughout the continental U.S. The reported detections of imidacloprid are displayed in Figure 5-1, along with the range of modeled peak EECs in surface water for the four types of

101 application methods (soil, foliar spray, combined methods and seed treatment). Although the detections of imidacloprid in surface water cannot be attributed to a particular type of application method, the overall range of modeled EECs appears within the range of detections reported in U.S. streams, rivers, lakes, and drainage systems. In recognizing that monitoring data are unlikely to capture daily peak concentrations per exposure modeling, the similarity in the overall range of detected imidacloprid concentrations provides support that the model-based EECs are environmentally realistic.

100,000

10,000 EECs Foliar Foliar EECs 1,000 Combined

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Soil Soil EECs

MonitoredConcentration(ng/L) Seed Seed EECs

10

1 1-Mar-99 25-Nov-01 21-Aug-04 18-May-07 11-Feb-10 7-Nov-12 4-Aug-15 Sampling Date

Creeks/Streams (Mixed) Rivers/Lakes Urban Sorms/Storm Drains Agricultural Drains

Figure 5-1. Detected Imidacloprid Concentrations in Surface Water (USGS, CDPR) Relative to the Range of Modeled Peak EECs

A second line of evidence provided by monitoring data is they can be evaluated against toxicity endpoints to ascertain potential risks associated with real world exposures. This type of comparison is shown in Figure 5-2 in which detected concentration of imidacloprid in surface water are compared to freshwater invertebrate acute and chronic toxicity endpoints used for risk estimation. These endpoints are based on acute and chronic toxicity data for the mayfly species, C. dipterum and C. horaria, respectively (Roessink et al., 2013). It is evident from this comparison that the majority of detected imidacloprid concentrations exceed both the chronic NOAEC of 10 ng ai/L and the chronic LOAEC of 30 ng ai/L, while a smaller proportion exceed the acute toxicity endpoint of 770 ng ai/L. This comparison suggests that sensitive aquatic invertebrates such as mayflies are potentially experiencing lethal and sublethal effects as a result of registered uses of imidacloprid. The nature of this comparison relative to other taxa of tested aquatic invertebrates is discussed in a subsequent section.

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100,000

10,000

Lowest Acute EC50

1,000

Acute Endpoint

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MonitoredConcentration(ng/L) LOAEC= 30 ng/L 10 Chronic Endpoint (10 ng/L)

1 1-Mar-99 25-Nov-01 21-Aug-04 18-May-07 11-Feb-10 7-Nov-12 4-Aug-15 Sampling Date Creeks/Streams (Mixed) Rivers/Lakes Urban Sorms/Storm Drains Agricultural Drains

Figure 5-2. Detected Imidacloprid Concentrations in Surface Water (USGS, CDPR) Relative to Acute and Chronic Toxicity Endpoints for the Mayfly, C. dipterum and C. horaria, Respectively.

Ecological incidents

One ecological incident was reported in the EIIS that involved imidacloprid application and associated impacts on aquatic invertebrates (I007892-007). Specifically, it was reported that a granular formulation of imidacloprid (Merit 0.5G) was applied to a lawn that was located approximately 1000 ft from a storm drain approximately 1 mile from a creek. Heavy rainfall reportedly occurred for two days following the pesticide application. It was further reported that some 3,000 crawfish died along a half mile stretch of the creek and concentrations of imidacloprid were detected between 0.17 to 1.3 µg ai/L. This incident was considered a registered use of the product and suggests (but does not conclusively prove) that outdoor applications of the granulated product near waterways immediately prior to a significant rainfall event can lead to exposures that impact aquatic invertebrates.

5.2.3. Description of Assumptions, Sensitivity, Uncertainty and Data Gaps

A. Exposure Assessment

Exposure modeling was used to estimate surface water EECs for imidacloprid. The results obtained are dependent on the model formulation and inputs used for the various use patterns. Sources of 29 uncertainty related to the model formulation have been described elsewhere28F . However, uncertainties associated with inputs will be discussed hereunder. Uncertainties that are associated with modeling

29 https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/models-pesticide-risk-assessment#aquatic 103 inputs include: chemical parameters, application dates, labeled application rates, drift fraction, and the choice of representative scenario(s). Chemical parameters were selected from laboratory fate and 30 transport data for imidacloprid as per the standard procedure for modeling29F . Additionally, spray drift fraction was calculated for various application procedures (i.e., ground, aerial and air-blast) and labeled 31 buffer zones as per the procedure outlined in the document referenced below30F . Selecting parameters for application rates, application dates, representative scenarios required a substantial amount of effort due to the extensive number of use patterns, restrictions, application types (e.g., foliar, soil, seed and combined) and procedures used in soil applications for imidacloprid. In the exposure modeling for this assessment, appropriate parameters for each use pattern were selected to abide by the label language and what might represent actual field applications.

Application Dates/Timing

For treated seeds, application dates were arbitrarily set at 7-days before the emergence date for the crop scenario used in modeling. The application dates selected may not represent the actual dates at which planting occurs in the field because of the following reasons:

(1) Planting date and emergence dates may vary depending on factors such as weather and soil type; (2) Re-seeding may occur in certain situations to achieve the desired number of plants/acre; (3) 7 days may not represent the actual time needed for crop emergence; (4) Emergence dates for scenarios used to represent crop groups may not represent all the crops in the group.

EECs are expected to be higher for seeds planted at shallow depth and when the selected planting dates are close to rain events relative to EECs from seeds planted at deeper depths and when planting dates are further from rain events. Furthermore, EECs are expected to increase because of re-seeding due to the increase in application rate.

For foliar and soil applications, uncertainties associated with application dates are expected to be reduced substantially because the batch run feature of the model was used in this assessment. Many simulations were executed for pre-determined application windows based on the label and information from open literature. Application windows were based on factors derived from the labels including timing/length of application, crop stage(s) at time of application, pre-harvest intervals, and restrictions related to pollinator protection. However, there is a possibility of unspecified application dates that are close to rain events because of limitations on the length of the window/step used in modeling. The absence of such dates will result in the estimation of lower EECs.

30 https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/guidance-selecting-input-parameters-modeling 31 Reference: Guidance on Modeling Offsite Deposition via Spray Drift for Ecological and Drinking Water Assessments (Document released for public comment on 3/26/2014 and the Agency received over 5000 public comments (Docket ID; EPA- HQ-OPP-2013-0676). The finalized guidance document is yet not available on the Agency’s website, but a courtesy copy is available upon request.

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Labeled Application Rates

Labeled application rates for crops, crop groups/sub-groups were individually specified on the labels for various application types (foliar, soil and seed treatment) with a stipulation that combined application methods up to the maximum seasonal and yearly rates may be used. The labels state which application types may be combined without specifying individual rates. In this assessment, combined application rates were selected based on a conservative approach. For each use pattern permitted by the label, the maximum label rate was calculated from a reduced soil rate plus the total foliar rate. This approach was selected because preliminary modeling indicated that higher EECs were obtained from foliar applications relative to both seed and soil applications; especially if a soil application is combined with injecting, watering-in and/or drenching the pesticide into the root zone of the crop. These combined application rates used for modeling may not be typical for imidacloprid applications. The use of such combined applications by the farmer is expected to vary depending on many factors such as application cost, timing of pest pressure, available application equipment, and soil and weather conditions. Uncertainty in this case arises when EECs based on combined applications do not reflect the combination of application methods actually being applied in the field.

Seasonal application rates in most imidacloprid labels specify that these rates are equal to the yearly rates. For some crops, however, three application seasons/year are permitted. Three seasonal applications are permitted for the following crops groups: Brassica, Cucurbits, Herbs & Spices, Leafy greens, Leafy petiolate, Legumes (except soybean), Strawberry and Tuberous corm vegetables. Since the current surface water model simulates application(s) for only one crop/year, it was assumed that the seasonal rate is equal to yearly rate for all the above-mentioned crop groups. This assumption means that calculated EECs for these crops were based on a significantly reduced rate (i.e., by one third) and consequently, the EECs for these crops are similarly reduced in situations where more than one crop is planted/year. Notably, the approach of multiplying the application rate by three was not chosen because EECs would not reflect actual application and growing practices. Furthermore, crop scenarios in the current model simulate plant growth for one crop season and one application/set of applications. Therefore, if three seasonal rates were distributed throughout the year, only one of them will be appropriately simulated with the crop growth scenario while the other two will be incorrectly simulated without the presence of the crop. Again, EECs generated by distributing the rate throughout the year will not accurately represent reality. A change in the label is required to match the assumption made in this assessment, otherwise EECs are significantly underestimated for crops with multiple growing seasons/year. By way of example, EECs resulting from use on herbs & spices was simulated using a research version of PWC which accepts applications to more than one season/year. EECs estimated from this simulation were 15.8 ppb for peak and 11.0 ppb for the 21-day average compared to the one season/year result of 3.02 ppb for peak and 2.22 ppb for 21-d average.

Application methods

Selecting representative application methods for modeling was a straightforward task for ground/aerial foliar and soil surface application (e.g., above crop for ground/aerial foliar application and below crop for soil surface applications). In contrast, uncertainties were associated with selecting representative application methods for other types of labeled applications. Examples include:

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1. In furrow liquid spray directed on or below seed: In this case, the modeling method used for this assessment was “@depth” with seed depth obtained from the literature for the crop of the scenario representing that crop or crop group. The selected depth may accurately represent the crop but may not represent the planting depths for other crops in the same crop group. Additionally, planting depth is variable even for within a crop as it depends on many factors such as soil type, soil moisture profile, planting time, and current and expected weather condition. This depth could be lower than usual in some situations. For examples, five references reported that the usual planting depth for soybeans varied from 1 to 2” depending on soil conditions and 32 time of planting and it was 0.5” for moist soil31F . In this assessment, it was assumed that the seeds will be planted by equipment whereas the spray will be directed into the seeds with no spray drift. This will generate lower EECs than if spray drift is assumed. In the field, spray drift may reach the sides of the row above the modeled seed depth or may occur from shallow planting depths due to imperfect planting in un-leveled soil surfaces. Such conditions are expected to result in higher EECs than those modeled because of increase in pesticide mass available for run-off especially when planting depth is < 2-cm.

As shown in Figure 5-3, the effect of seeding depth on modeled EECs is significant. The plots shown in Figure 5-3 were established by simulating imidacloprid coated soybean seeds at variable depths with no drift. Simulated peak EECs substantially increased from zero µg/L at the depth of 2 cm to 16 µg/L at 0.254 cm. It is noted that literature reported usual planting depth of 1 to 2” (> 2cm) for soybean seeds yield zero EECs compared to EECs increasing to a peak of 3 µg/L when the seeds are planted at 0.5”. The later planting depth was reported to occur in moist soils.

Figure 5-3. Change in Modeled EECs as a Function of Seeding Depth Used in Modeling.

32 1st reference URL: http://crops.extension.iastate.edu/cropnews/2014/05/soybean-planting-depth-considerations-iowa *2nd reference URL: http://unitedsoybean.org/article/are-you-planting-at-the-right-depth/ * 3rd reference URL: http://cornandsoybeandigest.com/5-top-planting-tips-help-boost-soybean-returns * 4th reference URL: https://www.aganytime.com/asgrow/mgt/planting/Pages/Placement.aspx 5th reference URL: http://www.agriculture.com/crops/soybeans/production/Planting-soybeans-too-deep-decreases-yield- potential_141-ar2488 106

2. Modeling coated seeds: “@depth” with no drift was used in modeling this type of imidacloprid use. One exception was soybeans in which combined application of seed and foliar was used in order to arrive at a conservative EEC estimate. This was done to avoid estimation of zero exposure in part because usage data indicate that 36% of the average yearly usage of imidacloprid was for seed treatment (average is calculated from data for the years from 2004 to 2012; refer to Figure 3-1, above). Concern about surface water exposure from soybean is the reason for choosing a conservative approach in modeling this particular use pattern. Special attention is given to imidacloprid seed treatment use because of significant usage as a percentage of total applied, reports of dusting-off during planting, and reported of widespread occurrences of neonicotinoid insecticides, including imidacloprid, in streams which was mainly attributed to seed treatment with imidacloprid (discussed further below).

Dust-off

Reported annual usage of imidacloprid in soybeans approaches 50% of the total national usage since 2010 (refer to USGS National usage data, Figure 3-3). Based on average annual usage data for 2004 to 2013, BEAD reported that the largest increase in usage was observed in soybeans seed treatment, which increased from 300,000 to 400,000 lbs. of active ingredient average applied annually. As shown in Figure 3-13, the total annual usage of imidacloprid in soybean crop constitutes 39% of the total yearly usage of which 36% for seed treatment and 3% for other types of usage (i.e., foliar and soil).

Dust-off from planting of corn seeds treated with clothianidin or thiamethoxam (two other neonicotinoid insecticides) were estimated to be 9 ng of the a.i/cm2 (Reed M. Johnson, Personal 33 communication)32F . This estimate is based on the mass of pesticide deposited on slides that were placed in the field during corn planting with pesticide-coated seeds. Seeds were treated at a rate of 1.25 mg a.i/seed which is equivalent to an application rate of 0.095 lb. a.i/A on the assumption corn seeding rate of 35,000 seeds/A. Dust-off mass of 9 ng/cm2 is equivalent to 0.0008 lb./A which is equivalent to 0.83% of the application rate.

To estimate the potential surface water concentration associated with dust-off, an application rate equal to 0.83% was modeled using MSsoybeanSTD scenario on the assumption that dust is deposited into the surface of the soil (i.e., surface applied). EECs obtained as a result of modeling the estimated “dust-off” mass were 0.05/0.034/0.020 µg/L for Peak/21-day/60-day averages compared to zero when dust-off is not considered. An uncertainty with this approach is that dust-off may be affected by the type of seed, type of seed treatment, environmental conditions and planting equipment. Furthermore, it is noted that dust-off may also occur when granular pesticide is applied with the seeds instead of planting treated seeds. In this assessment, modeling for seed coated seeds did not consider dust-off due to the uncertainties stated above in determining the mass of the pesticide dust generated during planting operations. Therefore, uncertainty exists for EECs obtained from modeling seed-coated seeds.

Neonicotinoids, including imidacloprid, were found prevalent in nine streams monitored during the 2013 growing season in a Midwestern agricultural area dominated by intense corn and soybean crops

33 Reed M. Johnson, The Ohio State University, College of Food, Agriculture and Environmental Sciences: "Johnson, Reed M." 107

34 Hladik et al, 2014)33F . Detection frequency and maximum/median concentration of imidacloprid were 23% and 42.7/<2 ng/L, respectively, in the 79 samples (Figure 5-4).

Figure 5-4. Monitored Maximum Concentrations Frequency of Detection in 9 Midwestern Streams.

Temporal patterns were identified for the fifteen detections for imidacloprid. One sample with a low detection frequency and concentration of 2 ng/L was identified for the period from March to April, nine samples with high detection frequency and concentrations ranging from 2 to 43 ng/L for the period from May to June and 4 samples with a mid-range detection frequency and concentrations ranging from 2 to 25 ng/L for July. The three identified time periods were associated with rainfall events during pre- planting, planting and mid growing season, respectively, suggesting seed treatments as the likely source for the observed concentrations. Additionally, the one site with a more intensive and hydrologic-based sampling design had the highest measured concentrations of all studied sites. This finding supports the importance of targeting monitoring and more frequent sampling (short sampling intervals).

A four-year study on water quality in Iowa’s portion of the Prairie Pothole region was conducted to monitor levels of neonicotinoids in surface water of drained wetlands when water ponded up on them 35 (Evelsizer and Skopec; 2016)34F . Levels of these pesticides were measured in 16 samples representing 25 sites in corn and soybean areas during pre-planting (May 15), during planting (May 28 to June 4), and after planting (June 17 to June 18). Imidacloprid was detected in 23 of 48 (48%) of the samples with a maximum concentration of 120 ng/L and peak detections occurring during the planting season (Figure 5- 5). Specifically, Figure 5-5 is a graphical representation of the imidacloprid detection frequencies measured before, during and after spring planting (April through June).

34 Hladik ML, Kolpin DW, Kuivila KM (2014) Widespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region, USA. Environmental Pollution 193:189–196 35 Vince Evelsizer & Mary Skopec. 2016. Pesticides, Including Neonicotinoids, in Drained Wetlands of Iowa’s Prairie Pothole Region; Society of Wetland Scientists.

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Figure 5-5. Observed Change in Mean Concentrations and Detection Frequencies of Imidacloprid in During the Planting Season of Corn in Drained Wetlands in Iowa

B. Effects Assessment

The effects characterization conducted in this assessment contains various assumptions and uncertainties that warrant identification and discussion. Uncertainties associated with the effects characterization described below include: the representativeness of tested aquatic species, extrapolating effects from the laboratory to the field, variability in species sensitivity and the consideration of higher tier toxicity data for imidacloprid.

Representativeness of Tested Aquatic Species

Fish and Aquatic-Phase Amphibians. Acceptable or supplemental/qualitative data for imidacloprid were available for three species of fish and one species of amphibian. While these data far under- represent the diversity of fish and amphibian species in the U.S., multiple lines of evidence suggest that the risk conclusions for fish and amphibians reached in this assessment are not likely to be sensitive to this uncertainty. For example, the empirical data indicate that imidacloprid is slightly to practically non- toxic to fish and amphibians on an acute exposure basis (LC50 values ranged from 53-229 mg ai/L). Since the highest EECs and monitored concentrations identified from this assessment are approximately 10,000X lower than these acute toxicity values, untested species of fish or amphibians would need to be four orders of magnitude more sensitive than tested species to raise risk concerns, which is considered highly unlikely. A large difference also exists between chronic EECs and chronic NOAECs for fish (approximately three orders of magnitude difference). Furthermore, information regarding the mode of action of neonicotinoids (including imidacloprid) suggests that their selectivity to invertebrates (and the corresponding lack of sensitivity of vertebrate species) is related to key differences in the composition of nicotinic acetylcholine receptors among these taxonomic groups (Tomizawa & Casida, 2003).

Freshwater Invertebrates. Relative to many pesticides, imidacloprid has been tested on a broad array of 109 freshwater invertebrate species. Acute toxicity test data (acceptable or qualitative) are available for 28 species of freshwater invertebrates distributed among 4 classes of arthropods (Branchiopoda, Insecta, Ostracoda, Malacostraca) and two other phyla (Nemata, Annelida). Aquatic insects alone are represented by 13 species. Despite this relatively robust acute toxicity data set with imidacloprid, the tested species represent a small fraction of the thousands of freshwater aquatic invertebrate species found in North America. Ephemeroptera (mayflies) appear to be among the most sensitive group of species tested to date, and reliable data are available for only three mayfly species. For evaluating chronic toxicity, acceptable or qualitative data are available for 14 species, eight of which are insects (Table 4-8). Mayflies also represent the most chronically-sensitive taxonomic group and chronic data are 36, 37 available for two species. With over 600 species of mayflies found in the U.S.,35F 36F it is not unreasonable to presume that more sensitive mayfly species to imidacloprid have yet to be tested. One method for selecting regulatory endpoints that addresses some of the differences in the amount and distribution of aquatic toxicity data is the use of species sensitivity distributions (SSDs). In the subsequent revision to this assessment, the SSD approach will be considered further. However, a comparison of regulatory endpoints for acute and chronic toxicity used in this assessment to those from other institutions which used the SSD approach suggests that the overall risk conclusions for aquatic invertebrates would not be sensitive to the use of the SSD approach (see additional discussion below).

Saltwater Invertebrates. Far fewer species of saltwater invertebrates are represented in the acute and chronic toxicity database with imidacloprid (6 species for acute exposures and 2 species for chronic exposures). This in part reflects the availability of fewer toxicity test protocols for saltwater invertebrates compared to freshwater invertebrates. Therefore, the uncertainty associated with capturing the more sensitive saltwater species of invertebrates is considered greater than that for freshwater invertebrates where a larger toxicity data set is available.

Extrapolation of effects from the laboratory to the field

This effects characterization is based on toxicity studies conducted under controlled environmental conditions in the laboratory. Exposures and conditions are held constant to minimize confounding effects on interpretation of the concentration-response relationships. However, conditions in the field differ markedly from those in the laboratory. For example, temperature, flow, water quality, photoperiod, food availability, organism health, etc., all vary widely in the natural environment which can affect an organism’s response to a specified chemical exposure. For a given chemical exposure, organisms may be more sensitive in the field relative to the laboratory (e.g., under periods of physiological stress or starvation) or they may be less sensitive (e.g., for strains that have undergone some degree of genetically-adaption, conditions that reduce a chemical’s bioavailability). A further uncertainty with extrapolating effects from single-species tests conducted in the laboratory to species in the field is that factors affecting population fitness and dynamics are not incorporated. The vulnerability of a population to a given chemical perturbation may be influenced by factors besides toxicological sensitivity, including fecundity, predation, immigration, emigration, generation time, age class structure, etc. Therefore, there is uncertainty to the extent that these and other factors alter population fitness

36 http://www.nwf.org/wildlife/wildlife-library/invertebrates/mayflies.aspx 37 https://www.entm.purdue.edu/mayfly/na-species-list.php 110 relative to a species’ toxicological sensitivity as determined by laboratory testing. Interactions among species are also not addressed in this effects assessment. Depending on the exposure and the degree of structural and functional redundancy which exists in an ecosystem, the ecosystem level impact of a given chemical perturbation on one species or population may differ. Ecosystems with high structural and functional redundancy among a given taxonomic group or ecological function (e.g., shredders) are generally considered more resilient with respect to perturbations that affect one sensitive species. However, the opposite may also be true as biodiversity and functional redundancy of ecosystems decrease.

Variability in Species Sensitivity

In accordance with OPP ecological risk assessment guidance, risk estimation is based on the most sensitive acute and chronic toxicity endpoint that is considered acceptable for quantitative use within freshwater and saltwater vertebrates and invertebrates (USEPA 2004). Within the context of available toxicity data, this approach is considered “conservative” in that averages of toxicological endpoints within and across species are not used in risk estimation. This approach is taken in part because of the limited toxicity data that typically is available for pesticides relative to the number of species in potentially affected ecosystems. Nonetheless, it is instructive to evaluate the extent to which risk assessment conclusions are affected by using the most sensitive endpoint among all freshwater aquatic invertebrate taxa.

With imidacloprid, acute and chronic risk estimation for freshwater invertebrates was based on an acute

EC50 of 0.77 µg ai/L for the mayfly, C. dipterum and a chronic NOAEC of 0.01 µg ai/L for the mayfly, C. horaria. As discussed previously, mayflies appear to be among the more sensitive taxonomic group to imidacloprid. In an effort to evaluate the sensitivity of the risk conclusions to the choice of mayflies as the basis of the freshwater invertebrate risk estimation, the lowest acute toxicity values (EC50, LC50, acceptable or qualitative) for various taxonomic groups of freshwater invertebrates are compared with the acute EECs used in risk estimation (Figure 5-6). The y-axis of this figure represents the percentage of EECs determined for each application method that exceed a given value on the x-axis. The vertical lines represent the lowest acute toxicity value within each taxonomic group. Since these EECs are predicted concentrations with a 1-in-10 year return interval obtained from different modeling scenarios, the EECs shown in Figure 5-6 do not represent a statistical distribution of concentrations among use scenarios. Rather, Figure 5-6 illustrates the range of EECs determined across the multiple application methods and crop scenarios modeled in this risk assessment. It is evident from Figure 5-6 that acute EECs from soil, foliar and combined application methods exceed acute toxicity endpoints for multiple taxonomic groups (e.g., ostracods, caddisflies, branchiopods and dipteran insects. The highest acute EECs for foliar and combined application methods also exceed acute toxicity values for the comparatively more resistant amphipods. For seed treatment uses, acute EECs are below acute toxicity values for all taxonomic groups except mayfly and ostracod.

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100% 90% 80% 70%

60% Diptera Acute 50%

40% Amphipod Acute 30% 20%

10% Acute Mayfly EEC Exceedance Frequency Exceedance EEC 0% 0.00 0.01 0.10 1.00 10.00 100.00 Concentration (ug ai/L) Foliar EECs Combined EECs Soil EECs Seed EECs Ostracod Acute Caddisfly Acute Branchiopod Figure 5-6. Percentage of Imidacloprid Acute EECs That Exceed Taxon-Specific Acute Toxicity Values for Freshwater Invertebrates

The same type of comparison was also conducted with chronic EECs and chronic toxicity values (Figure 5-7). It is evident that chronic EECs determined from foliar and combined application method scenarios exceed not just the mayfly chronic toxicity endpoint of 0.01 µg ai/L, but also chronic toxicity endpoints for dipteran insects (e.g., midge), megalopteran insects (cranefly) and branchiopod crustaceans (C. dubia), all with chronic NOAECs or LOAECs of 0.3 µg ai/L. The chronic EECs for foliar and combined application methods exceed the most sensitive chronic values from the three other taxonomic groups by varying percentages. Chronic EECs for soil and seed treatment applications are below all chronic toxicity endpoints when incorporated below 2 cm in the soil. For seed treatment applications with < 2 cm incorporation depth, about one third to one half of the chronic EECs exceed the most sensitive chronic toxicity endpoints for other taxonomic groups besides mayflies.

100% 90% 80%

70%

Chronic Amphipod Amphipod 60% 50% 40% 30% Chronic Stonefly 20%

10% Chronic Mayfly

EEC Exceedance Frequency Exceedance EEC

Diptera, Branchiopod, Diptera, Chronic Cranefly 0% 0.00 0.01 0.10 1.00 10.00 100.00 Concentration (ug ai/L)

Foliar EECs Combined EECs Soil EECs Seed EECs Isopod Chronic Figure 5-7. Percentage of Imidacloprid Chronic EECs That Exceed Taxon-Specific Chronic Toxicity

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Values for Freshwater Invertebrates

The comparisons presented in Figure 5-6 and Figure 5-7 indicate that the risk findings for freshwater aquatic invertebrates do not depend solely on the high acute and chronic sensitivity of mayflies to imidacloprid. Rather, acute and chronic EECs exceed toxicity values for species distributed among multiple taxonomic groups of aquatic invertebrates.

A similar conclusion regarding the vulnerability of multiple taxa to registered uses of imidacloprid is reached with respect to monitored concentrations of imidacloprid in U.S. surface waters (Figure 5-8). Specifically, of the nearly 3,000 samples analyzed for the presence of imidacloprid in rivers and lakes, about 3.3% exceed the chronic toxicity NOAEC for mayfly of 10 ng ai/L and 0.2% exceed the NOAEC for dipterans, cranefly, and branchiopods (300 ng ai/L). Exceedance frequencies are higher in streams, where about 13% of the 4,200+ reported measurements exceed the mayfly chronic NOAEC of 10 ng ai/L and 1.6% exceed that for dipterans, cranefly, and branchiopods. Surface waters sampled during or shortly after storm events (505 samples) contained imidacloprid concentrations with the greatest frequency of exceeding the chronic toxicity endpoints (17.4% for mayfly, 4.4% for dipertans, cranefly and branchiopods). Importantly, samples with levels reported to be below the limits of detection (2-500 ng ai/L) were assumed to be 0 ng ai/L. Therefore, these exceedance frequencies likely underestimate the actual exceedance frequencies of the chronic toxicity values for sensitive freshwater invertebrates, since the levels of detection often exceeded these values (10 and 300 ng ai/L). This information suggests that monitored concentrations of imidacloprid are exceeding chronic toxicity endpoints for sensitive aquatic invertebrates with frequencies that may be ecologically significant.

Rivers & Lakes Streams Storm Events 100%20%

15%

10%

Isopod Chronic Isopod

Diptera, Branchiopod, Diptera, Chronic Cranefly

5% Chronic Mayfly

Stonefly Stonefly Chronic

Exceedance FrequencyExceedance Amphipod Amphipod Chronic

0% 01 10 100 1,000 10,000 Imidacloprid Concentration (ng a.i./L)

Figure 5-8. Exceedance Frequency of Imidacloprid in USGS Surface Water Monitoring Samples Relative to Chronic Toxicity Endpoints for Freshwater Invertebrates (non-detects assumed = 0)

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Use of Higher Tier Toxicity Data

A significant body of higher tier aquatic toxicity data (e.g., outdoor mesocosm studies) are available for imidacloprid. This information has been reviewed in assessments produced by regulatory institutions including the European Food Safety Authority (EFSA 2014) and Canada’s Pest Management Regulatory Agency (PMRA 2016). These data have also been reviewed in peer-reviewed publications by multiple academic researchers (e.g., Morrissey et al., 2015; Anderson et al., 2015; Pisa et al., 2015; Smit et al., 2015). In addition, the Bayer Crop Science (the technical registrant for imidacloprid) also commissioned an aquatic risk assessment of imidacloprid which included a detailed review of the higher tier data (BCS 2016). Due to resource and time constraints, an independent review of the higher tier aquatic toxicity data for imidacloprid was not conducted as part of this preliminary ecological risk assessment. Review and interpretation of these higher tier studies is much more resource intensive compared to lower tier studies in part because of the greater complexity in assessing exposure and statistical analysis of effects. However, the Agency expects to revise the preliminary ecological risk assessment to reflect public comment and any additional refinements deemed necessary to support risk management decisions. Such refinements, if deemed necessary, would likely include an independent review of the mesocosm data.

In the interim and as part of this preliminary ecological risk assessment, the Agency has summarized the conclusions of other reviews of the higher tier data in an effort to evaluate the sensitivity of its risk conclusions to this information (Table 5-8). Adverse effects of imidacloprid have been noted at concentrations as low as 0.1 µg ai/L in these higher tier studies, but the effect thresholds vary widely among the available studies. Some of this variation likely reflects differences in test designs (e.g., pulsed vs. continuous exposures; single vs. multiple treatment concentrations; different exposure durations) and types of taxa included in the studies. In general, aquatic insects (in particular Ephemeroptera) appear most sensitive to imidacloprid exposure based on these reviews, which is consistent with the findings from the lower tier (laboratory) data reviewed in this assessment. Furthermore, while a significant body if information is available, both EFSA and PMRA concluded that the available information from the higher tier (mesocosm) studies is insufficient to establish a higher-tier effects threshold for imidacloprid (e.g., a higher tier NOAEC). Specifically, PMRA (2016) stated:

“Despite consistent results among individual mesocosm studies demonstrating negative effects to aquatic invertebrates, a collective interpretation of the data is difficult and problematic due to a number of deficiencies that include: 1) An inadequate number of exposure concentrations; 2) Population/community level effects were not measured; 3) An application regime that is not representative of the most conservative exposure scenario; 4) An inadequate study duration to measure recovery; 5) An exposure scenario that is not applicable to the Canadian use pattern (for example, rice seedling treatment followed by transplant to mesocosms); and 6) Low abundance of sensitive invertebrate species, i.e., Ephemeroptera, prevented reliable statistical evaluation (low power) of effect and recovery.” (p. 50)

EFSA (2014) concluded that: 114

“Overall, on the basis of the available mesocosm studies, the experts concluded that a tier-3 RACsw;ac to cover more sensitive aquatic species cannot be derived due to the lack of information on more sensitive species, such as Ephemeroptera. Furthermore, this conclusion was also supported by the additional information derived from the publicly available mesocosm studies, which indicated effects on Ephemeroptera at concentrations below the mesocosm NOECs (Alexander et al., 2008 and Colombo et al., 2013); see the study evaluation notes, section 5.5; EFSA, 2014b).” (p. 11)

Pisa et al. (2015) also concluded that the available higher tier data for imidacloprid was inadequate for establishing a safe level of imidacloprid with aquatic macroinvertebrate communities and noted the need for higher tier studies involving exposure levels below 0.1 µg ai/L. Morrissey et al. (2015) noted in their review of stream mesocosm data that effects on invertebrate taxa occurred at environmentally- relevant concentrations from 0.01 to 24.1 µg ai/L for imidacloprid or thiamethoxam, although basis of this range was not clear from their publication. Smit et al. (2015) suggested that 0.17 µg ai/L as a Maximum Acceptable Concentration (MAC) based on their review of five mesocosm studies. Finally, in their review of the higher tier aquatic toxicity literature, Bayer Crop Science (BCS, 2016) noted that higher tier effects thresholds varied from 0.24 to >180 µg ai/L. Furthermore, the study authors used the available data to construct a higher tier SSD for imidacloprid. Based on this SSD, an HC5 of 1.01 µg ai/L was developed and recommended for use in risk assessment.

Table 5-8. Summary of Recent Regulatory Assessments and Literature Reviews of Imidacloprid Higher Tier Aquatic Effects Studies Range of Adverse Number of Studies Study Effects Thresholds Overall Conclusions Reviewed Noted ~ 19 (many were Data considered inadequate to derive EFSA (2014) considered not relevant <0.1 to > 12 µg ai/L tier 3 reference aquatic concentration and/or reliable) (RAC) Data considered inadequate to PMRA (2016) ~13 <0.1 to >12 µg al/L establish higher tier NOAEC Higher tier HC5 0f 1.01 µg ai/L BCS (2016) ~21 0.24 to >180 µg ai/L recommended Effects on macroinvertebrate taxa Morrissey et al. 13 0.01-24 µg ai/L ranging from 0.01 to 24 µg ai/L (2015) (imidacloprid or thiamethoxam) Overall safe concentration could not be established with community-level Pisa et al. (2015) 6 0.1-12 µg ai/L mesocosm studies; they suggest it would be <0.1 µg ai/L Authors suggest 0.17 µg ai/L as a Maximum Acceptable Concentration Smit et al. (2015) 5 <0.1 to <12 µg ai/L (MAC) from mesocosm data based on NOEC of 0.51 µg ai/L and application factor of 3

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Therefore, while this preliminary aquatic risk assessment with imidacloprid did not incorporate an independent review of the higher-tier mesocosm data available for aquatic invertebrates, all but one of the aforementioned reviews suggests that this omission would not likely change the overall risk conclusions reached in this assessment. Three of these reviews indicate that the data are insufficient to establish any higher tier effects threshold for imidacloprid while one (Smit et al. 2015) suggests a value (0.17 µg ai/L) which would also be exceeded by the vast majority of modeled EECs (Figure 5-6) in addition to monitored concentrations (Figure 5-1). The review by BCS (2016) which proposes a higher tier effects threshold of 1.01 µg ai/L would still be exceeded by the vast majority of EECs from the foliar and combined application methods but none of the seed treatment EECs. It is worth noting that BCS (2016) also included a spatially-explicit, probabilistic risk assessment for imidacloprid which concluded de minimis or low risks for all registered uses of imidacloprid modeled.

Comparison with Other Regulatory and Non-Regulatory Assessments

Multiple regulatory and non-regulatory aquatic risk assessments have recently been conducted with imidacloprid, including but not limited to, Canada’s Pest Management Regulatory Agency (PMRA 2016), the European Food Safety Authority (EFSA 2014) and Bayer Crop Science (BCS 2016). It is therefore instructive to compare aspects of these assessments to ascertain the degree of similarities and differences in the assessments. Table 5-9 provides a summary of different attributes of these assessments with respect to aquatic toxicity endpoints used to estimate risks and their overall risk findings.

Table 5-9. Comparison of Recent Regulatory and Non-Regulatory Aquatic Risk Assessments for Imidacloprid Endpoint Description USEPA 2016 PMRA 2016 EFSA 2014 BCS 2016 Freshwater Invertebrates (µg ai/L) Acute Endpoint 0.39 0.36 0.098 1.73 (Lowest EC50 of (Acute HC5) (Acute HC5 of 0.49/5) (Acute HC5) (Basis) 0.77/2) Chronic Endpoint 0.01 0.021 0.009 0.039 (Chronic HC5 of (Basis) (Lowest NOAEC) (Chronic HC5/2) (Chronic HC5) 0.027/3) Saltwater Invertebrates (µg ai/L) Acute Endpoint 16.5 1.37 n.d. n.d. (Basis) (Lowest EC50/2) (Acute HC5) Chronic Endpoint 0.16 0.33 n.d. n.d. (Basis) (Lowest NOAEC) (Lowest NOAEC) Risk Findings High acute and chronic Screening: 54-1,790 risk (select 0.3-296 (Tier 1) RQ range <0.01-2,130 (select scenario) representative 0.5-11.4 (Tier 2) scenarios) Refined: = low risk

The acute toxicity endpoint used in this assessment for calculating acute RQ values for freshwater invertebrates is 0.77 µg ai/L. Acute risk concerns to non-listed species are based on a LOC of 0.5.

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Therefore, this acute toxicity value was divided by two in order to properly compare to the regulatory endpoints reported by the other three assessments. It is evident that the EPA acute toxicity endpoint for freshwater invertebrate (0.39 µg ai/L) is within about 4X of those from PMRA, EFSA and BCS (Table 5-9). Despite different methodologies being used to derive the acute toxicity endpoints, EPA’s endpoint (0.39 µg ai/L) is very close to PRMA’s endpoint (0.36 µg ai/L). EFSA reported the lowest acute toxicity endpoint for freshwater invertebrates (0.098 µg ai/L), but this originated from an HC5 of 0.49 divided by an assessment factor of 5. BCS reported the highest acute toxicity endpoint (1.73) which may be due to differences in the data included in its derivation. In their assessment report, BCS excluded data from Roessink et al. (2013) due to concerns regarding how immobilization was quantified (no gentle prodding was employed). However, organisms were carefully observed for 20s for immobilization and communication with the study author indicated that mayflies did not recover after immobilization (i.e., 38 immobilization led to death)37F .

The chronic toxicity endpoints for freshwater invertebrates were also within a factor of 4X among the four assessments. The EPA and EFSA endpoints were most similar (0.01 vs. 0.009 µg ai/L) even though the EPA endpoint did not use an SSD approach. The BCS endpoint was the highest among the four (0.039 µg ai/L) but was only a factor of 2X greater than that used by PMRA.

For saltwater invertebrates, EFSA (2014) and BCS (2016) did not report separate assessment endpoints for the saltwater taxa (saltwater taxa were combined with the freshwater taxa in the BCS assessment). The EPA acute toxicity endpoint for saltwater invertebrates is 12X greater than that from PMRA. This likely reflects differences in the underlying methodology (lowest endpoint used by EPA vs. HC5 used by PMRA) in combination with the limited data available for saltwater invertebrate (6 species total). This small data set results in extrapolating the HC5 below the most sensitive species tested. Chronic endpoints were similar between EPA and PMRA, likely because the same data were used and both relied on the lowest available NOAEC.

Lastly, risk findings from EPA, PMRA and EFSA were comparable, as well as the screening portion of the BCS assessment. Notably, PMRA and EFSA only assessed representative uses rather than a broad set of uses per EPA and BCS. For its refined assessment, BCS (2016) employed a spatially-explicit, probabilistic approach which, according to their report, indicates “low or de minimis” risk from all uses assessed. The EPA is currently developing a spatially-explicit aquatic exposure model (SAM) but this model currently 39 requires additional refinement and validation prior to its use in regulatory assessment.38F

5.2.4. Endocrine Effects

As required by FIFRA and the Federal Food, Drug, and Cosmetic Act (FFDCA), EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity involving assessments of carcinogenicity, neurotoxicity,

38 Personal communication with P. Van der Brink, December 15, 2016. 39 USEPA. 2015. FIFRA Scientific Advisory Panel Minutes No. 2015-03. A set of Scientific Issues Being Considered by the EPA Regarding Devleopment of a Spatial Aquatic Model (SAM) for Pesticide Risk Assessment. Available at: https://www.regulations.gov/docket?D=EPA-HQ-OPP-2015-0424 117 developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influence, such as effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of the Preliminary Problem Formulation for Registration Review for Imidacloprid (USEPA 2008a), EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), imidacloprid is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP employs a two-tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 testing is designed to identify any adverse endocrine-related effects caused by the substance, and establish a dose-response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was published on June 14, 2013[1] and includes some pesticides scheduled for registration review and chemicals found in water. Neither of these lists should be construed as a list of known or likely endocrine disruptors.

Imidacloprid is on List 1 for which EPA has received all the required Tier I assay data, and in June, 2015 released its conclusions on the weight of evidence for the potential of imidacloprid to interact with the 40 estrogen, androgen, and thyroid pathways. Please refer to referenced link for this evaluation.39F

5.2.5. Threatened and Endangered Species Concerns

Consistent with EPA’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to federally listed threatened and endangered (listed) species from registered uses of pesticides in accordance with the Joint Interim Approaches developed to implement the recommendations of the April 2013 National Academy of Sciences (NAS) report, Assessing Risks to Endangered and Threatened Species from Pesticides. The NAS report outlines recommendations on specific scientific and technical

40 Available at: https://www.epa.gov/endocrine-disruption/endocrine-disruptor-screening-program-tier-1-screening- determinations-and 118 issues related to the development of pesticide risk assessments that EPA and the Services must conduct in connection with their obligations under the ESA and FIFRA. EPA will address concerns specific to imidacloprid in connection with the development of its final registration review decision for imidacloprid.

In November 2013, EPA, the U.S. Fish and Wildlife Service, National Marine Fisheries (the Services), and USDA released a white paper containing a summary of their joint Interim Approaches for assessing risks to listed species from pesticides. These Interim Approaches were developed jointly by the agencies in response to the NAS recommendations, and reflect a common approach to risk assessment shared by the agencies as a way of addressing scientific differences between the EPA and the Services. Details of the joint Interim Approaches are contained in the November 1, 2013 white paper, Interim Approaches for National-Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report.

Given that the agencies are continuing to develop and work toward implementation of the Interim Approaches to assess the potential risks of pesticides to listed species and their designated critical habitat, this ecological problem formulation supporting the Preliminary Work Plan for imidacloprid does not describe the specific ESA analysis, including effects determinations for specific listed species or designated critical habitat, to be conducted during registration review. While the agencies continue to develop a common method for ESA analysis, the planned risk assessment for the registration review of imidacloprid will describe the level of ESA analysis completed for this particular registration review case. This assessment will allow EPA to focus its future evaluations on the types of species where the potential for effects exists, once the scientific methods being developed by the agencies have been fully vetted. Once the agencies have fully developed and implemented the scientific methods necessary to complete risk assessments for listed species and their designated critical habitats, these methods will be applied to subsequent analyses of imidacloprid as part of completing this registration review.

6. RISK CONCLUSIONS

6.1. Fish and Aquatic-phase Amphibians:

No direct risks to fish or aquatic phase amphibians are indicated from any of the agricultural or non- agricultural uses assessed. The limited number of aquatic incidents reported for imidacloprid did not indicate direct adverse impacts on fish. Furthermore, available monitoring data indicate detected concentrations of imidacloprid are several orders of magnitude below levels shown to cause adverse effects in fish and aquatic-phase amphibians. While the risk of direct effects of imidacloprid to fish and amphibians is considered low, the potential exists for indirect risks to fish and aquatic-phase amphibians through reduction in their invertebrate prey base.

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6.2. Aquatic Invertebrates

As shown in Figure 6-1, acute and chronic risks to freshwater invertebrates are identified with the majority of registered uses of imidacloprid. 10000 Chronic RQ Chronic RQ Chronic RQ 1000 Chronic RQ 100 Acute RQ 10 Chronic LOC (1.0)

Risk Quotient Risk 1 Acute LOC (0.5) Acute RQ 0 Acute RQ Acute RQ 0 Soil Foliar Spray Seed Combined

Figure 6-1. Acute and Chronic Risk Quotients for Freshwater Invertebrates Associated with Various Application Methods

Aquatic Invertebrates (Foliar Spray and Combination Application Methods): The greatest potential risks identified for aquatic invertebrates pertained to uses with foliar and combination application methods. Specifically, all modeled uses associated with foliar spray and combination application methods showed the potential for acute and chronic risks to listed and non-listed freshwater invertebrates (acute RQ values ranged from 1.6 to 44 while chronic RQs ranged from 39 to 2130). Chronic risks were also identified for saltwater invertebrates from all foliar spray and combination application method scenarios modeled. For foliar applications, acute risks were not identified for non- listed saltwater invertebrates, but risks were identified for listed saltwater invertebrates.

Aquatic Invertebrates (Soil Application Methods): Acute and chronic risks to freshwater invertebrates were identified for both agricultural and non-agricultural soil application uses. Acute RQ values ranged from <0.01 to 15 and exceeded the acute risk to non-listed species LOC of 0.5 for over half of the agricultural and non-agricultural use scenarios modeled. Acute risks to listed freshwater invertebrate species were identified with 29 of the 31 agricultural use scenarios modeled (94%) and 8 of the 11 non- agricultural use scenarios modeled (73%). Soil applications made at depths > 2 cm resulted in no acute or chronic risks to aquatic invertebrates (coffee-soil injected; cucurbits-10 cm drench; poplar and Christmas trees-shanked in 20 cm). In addition, the commercial perimeter treatment (California scenario) resulted in RQ values below all levels of concern for freshwater invertebrates but those for the Florida scenario exceeded acute and chronic LOCs. Since acute toxicity endpoints were higher for saltwater invertebrates, none of the acute RQ values for the agricultural or non-agricultural use scenarios modeled with soil applications exceeded the non-listed species LOC of 0.5, however, 39% and 18% of the acute RQ values exceeded the listed species LOC of 0.05 for agricultural and non-agricultural

120 uses, respectively. The vast majority of use scenarios modeled with soil applications also indicated chronic risk concerns with freshwater and saltwater invertebrates (RQ range: <0.01 to 699).

Seed Treatment. The lowest overall aquatic risk profile among the application methods was indicated for application of imidacloprid-treated seeds, although risks were still identified with some use scenarios. Those uses with planting depths greater than 2 cm resulted in no runoff to aquatic ecosystems based on exposure modeling. This modeling does not take into account the potential contamination from deposition of abraded seed coat dust onto the treated field or adjacent areas and therefore, may underestimate aquatic exposure from the planting of treated seeds. Currently, EPA does not have standardized methods for quantitatively modeling dust off of abraded coating from treated seeds. For freshwater invertebrates, acute RQ values range from <0.01 to 1.6 while chronic RQ values ranged from <0.01 to 84. No acute risks were identified for listed or non-listed saltwater invertebrates. Chronic risks were identified for saltwater invertebrates with 3 of the 8 scenarios modeled (RQ range: <0.01 to 5.1).

Other Lines of Evidence. Surface water monitoring data with imidacloprid were available from over 7,000 samples spanning approximately 15 years. Nationwide monitoring by the U.S. Geological Survey revealed frequencies of detection from 5% (rivers and lakes) to 13% in streams. High detection frequencies were identified for estuaries (67%) and drainage canals (61%) but these values are uncertain due to the low number of samples available for these systems. It is evident, however, that concentrations of imidacloprid detected in streams, rivers, lakes and drainage canals routinely exceed acute and chronic toxicity endpoints derived for freshwater invertebrates. Maximum values reported exceed the freshwater chronic toxicity endpoint by two orders of magnitude and the acute toxicity endpoint by one order of magnitude. Only one aquatic incident was identified that involved a registered use of imidacloprid to turf. This incident involved mortality of crayfish along a stream following a runoff event after application to turf. Fish were not reported to be impacted in the stream. Lastly, the risk findings summarized in this assessment are in general agreement with recent findings published by Canada’s Pest Management Regulatory Agency and the European Food Safety Authority.

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7.2. Registrant-submitted Environmental Fate Study Database

161-1 Hydrolysis MRID Citation Reference

42055337 Yoshida, H. (1989) Hydrolysis of NTN 33893: Lab Project No: 88011/ ESR: 99708. Unpublished study prepared by Nihon Tokushu Noyaku Seizo K.K. 34 p.

161-2 Photodegradation-water MRID Citation Reference

42256376 Anderson, C. (1991) Photodegradation of NTN 33893 in Water: Lab Project Number: 88010: 101956. Unpublished study prepared by Nitokuno, ESR, Yuki Institute. 128 p.

161-3 Photodegradation-soil MRID Citation Reference

42256377 Yoshida, H. (1990) Photodegradation of NTN 33893 on Soil: Lab Project Number: 88012/ESR: 100249. Unpublished study prepared by Nihon Tokushu Noyaku Siezo K. K. 42 p.

161-4 Photodegradation-air MRID Citation Reference

48416902 Spiteller, M. (1993) Aerobic Metabolism of Imidacloprid, [Carbon 14]-NTN 33893, in an Aquatic Model Ecosystem. Project Number: PF/3950, M/1510516/9. Unpublished study prepared by Bayer AG. 51 p.

162-1 Aerobic soil metabolism MRID Citation Reference

42073501 Anderson, C.; Fritz, R.; Brauner, A. (1991) Metabolism of Pyridinyl-C 14- Methylene| NTN 33893 in Sandy Loam under Anaerobic Conditions: Lab Project Number: 101241; M1250187-4. Unpublished study prepared by Bayer Ag--Leverkusen. 82 p.

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45239301 Anderson, C.; Fritz, R.; Brauner, A. (1992) Metabolism of (Pyridinyl- (carbon 14)-Methylene) NTN 33893 in Loamy Sand Soil BBA 2.2 under Aerobic Conditions: Lab Project Number: M 1250187-4. Unpublished study prepared by Miles Incorporated. 83 p. 45239302 Fritz, C. (1992) Degradation of (Pyridinyl-(carbon 14)-Methylene) NTN 33893 in Silt Soil HOEFCHEN under Aerobic Conditions: Lab Project Number: M 1250187-4. Unpublished study prepared by Bayer AG. 54 p.

162-3 Anaerobic aquatic metabolism MRID Citation Reference

42256378 Fritz, R.; Hellpointner, E. (1991) Degradation of Pesticides Under Anaerobic Conditions in the System Water/Sediment: Imidacloprid, NTN 33893: Lab Project Number: 1520205-5: 101346. Unpublished study prepared by Bayer AG, Leverkusen-Bayerwerk. 69 p.

835.4300 Aerobic aquatic metabolism MRID Citation Reference

48416901 Wilmes, R. (1988) Aerobic Aquatic Metabolism of NTN 33 893. Project Number: PF/3466, M/1510204/3. Unpublished study prepared by Bayer Ag, Institute of Product Info. & Residue Anal. 50 p. 48416902 Spiteller, M. (1993) Aerobic Metabolism of Imidacloprid, [Carbon 14]- NTN 33893, in an Aquatic Model Ecosystem. Project Number: PF/3950, M/1510516/9. Unpublished study prepared by Bayer AG. 51 p. 48416903 Hennebole, J. (1998) Aerobic Metabolism of Imidacloprid, [Carbon 14]- NTN 33893, in an Aquatic Model Ecosystem: Amendment to Report 2. Project Number: MR/212/98, PF/4337, M/1510516/9. Unpublished study prepared by Bayer AG. 48 p. 49602702 Halarnkar, P.; Leimkuehler, W.; Davis, J. (1997) Characterization of Three Degradates of Imidacloprid from Aerobic Aquatic Biotransfor- mation. Project Number: 107547, 107547-1, N3072402. Unpublished study prepared by Bayer CropScience. 185p.

163-1 Leach/adsorption/desorption MRID Citation Reference

42055338 Fritz, R. (1988) Adsorption/Desorption of NTN 33893 on Soils: Lab Project Number: M 1310231/1: 99199. Unpublished study prepared by Bayer Ag.

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50 p. 42055339 Fritz, R.; Brauner, ? (1988) Leaching Behavior of NTN 33893 Aged in Soil: Lab Project Number: M 1210225/3: 99635. Unpublished study prepared by Bayer Ag. 45 p. 42520801 Williams, M.; Berghaus, L.; Dyer, D. (1992) Soil/Sediment Adsorption- desorption of (carbon 14)-Imidacloprid: Lab Project Number: N3182101. Unpublished study prepared by ABC Labs, Inc. 70 p. 42520802 Williams, M.; Berghaus, L.; Dyer, D. (1992) Soil/Sediment Adsorption- desorption of (carbon 14)-NTN-33823: Lab Project Number: N3182102. Unpublished study prepared by ABC Labs, Inc. 63 p. 43142501 Hellpointner, E. (1994) Degradation and Translocation of Imidacloprid (NTN 33893) under Field Conditions on a Lysimeter: Lab Project Number: ME/6/95: M/1330351/6: 106426. Unpublished study prepared by Bayer AG, Institute for Metabolism Research. 74 p. 43315201 Hellpointner, E. (1994) Degradation and Translocation of Imidacloprid (NTN 33893) under Field Conditions on a Lysometer: Amendment to the Original Report: Project Nos. M 1330351-6; 106426-1. Unpublished study prepared by Bayer AG. 12 p.

164-1 Terrestrial field dissipation MRID Citation Reference

42256379 Rice, F.; Judy, D.; Koch, D.; et al. (1991) Terrestrial Field Dissipation for NTN 33893 in Georgia Soil: Lab Project Number: N3022101: 101987. Unpublished study prepared by ABC Laboratories, Inc. 422 p. 42256380 Rice, F.; Judy, D.; Koch, D.; et al. (1991) Terrestrial Field Dissipation for NTN 33893 in Minnesota Soil: Lab Project Number: N3022103: 101988. Unpublished study prepared by ABC Laboratories, Inc. 510 p. 42256381 Rice, F.; Judy, D.; Koch, D.; et al. (1991) Terrestrial Field Dissipation for NTN 33893 in California Soil: Lab Project Number: N3022102: 101989. Unpublished study prepared by ABC Laboratories, Inc. 561 p. 42256382 Rice, F.; Schwab, D.; Noland, P.; et al. (1992) Terrestrial Field Dissipation in Turf for NTN 33893 in Georgia Soil: Lab Project Number: 393553: 102603. Unpublished study prepared by ABC Laboratories, Inc., and Miles Inc. 353 p. 42256383 Rice, F.; Judy, D.; Noland, P.; et al. (1992) Terrestrial Field Dissipation in Turf for NTN 33893 in Minnesota: Lab Project Number: 393543: 102604. Unpublished study prepared by ABC Laboratories, Inc., and Agri-Growth Research, Inc. 409 p. 42256384 Noland, P.; Koch, A. (1991) Analytical Method for the Determination of

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NTN 33893 in Soil Samples: Lab Project Number: 39272-2: 101984. Unpublished study prepared by ABC Laboratories, Inc. 82 p. 42256385 Noland, P.; Koch, A. (1991) Analytical Method for the Determination of NTN 33893 in Turf Samples: Lab Project Number: 39354-2: 101981. Unpublished study prepared by ABC Laboratories, Inc. 64 p. 42734101 Bachlechner, G. (1992) Dissipation of Imidacloprid in Soil Under Field Conditions: Lab Project Number: RA-2082/91: 103948. Unpublished study prepared by Miles Inc. 89 p. 44631501 Noland, P. (1996) NTN 33893 Freezer Storage Stability Study in Soil and Turf: Lab Project Number: 107369: N3022301: N3022303. Unpublished study prepared by Bayer Corporation: ABC Laboratories, Inc. 86 p. 48971801 Placke, F. (1998) Long-term Soil Dissipation Study with Confidor 70 WG in Apple Orchards in Germany Following Spray Application. Project Number: MR/758/98/OCR, 205680, 205699. Unpublished study prepared by Bayer AG. 183p. 48971802 Placke, D. (1998) Long-term Soil Dissipation Study with Xelmone 350 FS in Great Britain Following Seed Dressing of Winter Barley. Project Number: MR/196/98/OCR, 105716,105732. Unpublished study prepared by Bayer AG. 127p.

165-1 Confined rotational crop MRID Citation Reference

42556104 Vogeler, K.; Linke-Ritzer, P.; Brauner, A. (1992) NTN 33893 Residues in Rotational Crops: Pyridinyl-carbon 14-methyl|: Lab Project Number: 103812: M 130 0279-2. Unpublished study prepared by Bayer AG. 191 p. 165-2 Field rotational crop MRID Citation Reference

43245901 Minor, R. (1994) Admire (2.5 Granular)--Residues in Field Rotational Crops: Lab Project Number: N319RC01: 105153. Unpublished study prepared by EN-CAS Analytical Labs and Miles Inc. 1190 p. 44063701 Koch, D. (1996) Admire 2F--Magnitude of the Residue in Field Rotational Crops: Lab Project Number: AD19RC01: 107133: 43200. Unpublished study prepared by ABC Labs., Inc. and Bayer Corp. 779 p.

166-1 Ground water-small prospective

129

MRID Citation Reference

44790102 Dyer, D. (1999) Progress Report #5 and Study Termination Request: Imidacloprid (ADMIRE)--Small-Scale Prospective Ground-Water Monitoring Study, Montcalm County, Michigan, 1996: Lab Project Number: 5635.00: N3212401: N3212401-PR5. Unpublished study prepared by Bayer Corporation and Levine. Fricke.Recon, Inc. 92 p. 44790103 Dyer, D. (1999) Progress Report #4 and Study Termination Request: Imidacloprid (ADMIRE)--Small-Scale Prospective Ground-Water Monitoring Study, Montcalm County, Michigan, 1996: Lab Project Number: N3212401: N3212401-PR4: 5635.00. Unpublished study prepared by Bayer Corporation and Levine.Fricke.Recon, Inc. 307 p. 45094701 Dyer, D.; Helfrich, K. (1999) Progress Report #6: Imidacloprid (Admire)--Small-Scale Prospective Ground-Water Monitoring Study Montclam County, Michigan, 1996: Lab Project Number: N3212401: 5635.00: 109383. Unpublished study prepared by Bayer Corp. and LFR Levine. Fricke, Inc. 87 p. 45094702 Dyer, D.; Helfrich, K. (2000) Progress Report #7: Imidacloprid (Admire)--Small-Scale Prospective Ground-Water Monitoring Study Montclam County, Michigan, 1996: Lab Project Number: N3212401: 5635.00: 109596. Unpublished study prepared by Bayer Corp. and LFR Levine. Fricke, Inc. 80 p. 45094703 Lenz, M.; Helfrich, K. (2000) Imidacloprid (Admire)--Prospective Ground-Water Monitoring Study, California, Broccoli--Progress Report #12: Lab Project Number: 108939: H5034: N3212402. Unpublished study prepared by Bayer Corp. and LFR Levine. Fricke, Inc. 55 p. 45858201 Dyer, D.; Helfrich, K.; Billesbach, K. (2002) Imidacloprid--Small-Scale Prospective Ground-Water Monitoring Study, Montcalm County, Michigan, 1996: Lab Project Number: N3212401: 5635.00: CMXX-95-0229. Unpublished study prepared by Bayer Corporation, LFR Levine-Fricke, and Braun Intertec Corporation. 504 p. 45878701 Lenz, M.; Jackson, S.; Billesbach, K. (2002) Imidacloprid Prospective Groundwater Monitoring Study: Monterey County, California: Lab Project Number: N3212402: H5034: 110889. Unpublished study prepared by Bayer Corporation and Weber, Hayes & Associates. 813 p.

201-1 Droplet size spectrum MRID Citation Reference

43766502 Hewitt, A. (1995) Spray Drift Task Force: Atomization Droplet Size Spectra for Selective Active Ingredients: Lab Project Number: A92/004. Unpublished study prepared by SpraySearch- Daratech Pty. Ltd. and Spray Drift Task Force. 175 p.

202-1 Drift field evaluation

130

MRID Citation Reference

42256309 Lin, J. (1992) Field Measurement of NTN 33893 (Imidacloprid) Runoff from Small Turf Plots in Miles Research Park, Stilwell, Kansas: Lab Project Number: FR222301: 102606. Unpublished study prepared by Miles Inc. 135 p

835.1240 Soil column leaching MRID Citation Reference

49602701 Koenig, T. (2015) Leaching Behavior of Pesticide; Active Ingredient: Gaucho 70 WS; Standard Soil 2.1, 2.2, 2.3. Project Number: RR00493/6, RR00494/4, RR00495/2. Unoublished studay prepared by Bayer AG. 15p.

835.2370 Photodegradation of parent and degradates in air MRID Citation Reference

49759105 Oslosky, S. (2015) Waiver Request for Toxicology Preventol TM Insecticide (Additional Source) Imidacloprid. Unpublished study prepared by Lanxess Corporation. 10p.

835.4100 Aerobic soil metabolism MRID Citation Reference

49835802 Stupp, H.; Unold, M. (2011) Imidacloprid (NTN33893): Aerobic Soil Degradation as Influenced by Availability in Soil to Micro-Organisms. Project Number: M1251372/1, MR/367/96, M1251873/7. Unpublished study prepared by Bayer CropScience AG. 107p. 49835803 Stupp, H.; Unold, M. (2011) [Methylene-14C]Imidacloprid: Identification of Polar Zone Z1 Detected in Aerobic Soil Degradation Study. Project Number: M1251873/7, M1251372/1, MEF/10/901. Unpublished study prepared by Bayer CropScience AG. 63p.

835.6100 Terrestrial field dissipation MRID Citation Reference

48971801 Placke, F. (1998) Long-term Soil Dissipation Study with Confidor 70 WG in Apple Orchards in Germany Following Spray Application. Project Number: MR/758/98/OCR, 205680, 205699. Unpublished study prepared by Bayer AG. 183p.

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48971802 Placke, D. (1998) Long-term Soil Dissipation Study with Xelmone 350 FS in Great Britain Following Seed Dressing of Winter Barley. Project Number: MR/196/98/OCR, 105716,105732. Unpublished study prepared by Bayer AG. 127p. 49759105 Oslosky, S. (2015) Waiver Request for Toxicology Preventol TM Insecticide (Additional Source) Imidacloprid. Unpublished study prepared by Lanxess Corporation. 10p.

835.7100 Ground water monitoring MRID Citation Reference

49759105 Oslosky, S. (2015) Waiver Request for Toxicology Preventol TM Insecticide (Additional Source) Imidacloprid. Unpublished study prepared by Lanxess Corporation. 10p.

7.3. Registrant-submitted Ecological Effects Study Database

72-1 Acute Toxicity to Freshwater Fish MRID Citation Reference

42055314 Bowman, J.; Bucksath, J. (1990) Acute Toxicity of NTN 33893 To Blue gill (Lepomis macrochirus): Lab Project Number: 37860: 100348. Unpublished study prepared by Analytical Bio-chemistry Labs., Inc. 29 p. 42055315 Bowman, J.; Bucksath, J. (1990) Acute Toxicity of NTN 33893 to Rain bow Trout (Oncorhynchus mykiss): Lab Project Number: 37861: 100349. Unpublished study prepared by Analytical Bio-Chemistry Labs., Inc. 31 p. 42055316 Grau, R. (1988) The Acute Toxicity of NTN 33893 Technical to Rain- bow Trout (Salmo gairdneri) in a Static Test: Lab Project No: E 2800098-7: 101303. Unpublished study prepared by Bayer Ag. 18 p.

72-2 Acute Toxicity to Freshwater Invertebrates MRID Citation Reference

42055317 Young, B.; Hicks, S. (1990) Acute Toxicity of NTN 33893 To Daphnia magna: Lab Project Number: 37862: 10245. Unpublished study pre- pared by Analytical Bio-Chemistry Labs., Inc. 30 p. 42256303 England, D.; Bucksath, J. (1991) Acute Toxicity of NTN 33893 to Hyalella azteca: Lab Project Number: 39442: 101960. Unpublished study prepared by

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ABC Labs., Inc. 29 p. 43946601 Roney, D.; Bowers, L. (1996) Acute Toxicity of (carbon 14)-NTN 33823 to Hyalella azteca Under Static Conditions: Lab Project Number: 107315: N3823202. Unpublished study prepared by Bayer Corp. 34 p. 43946602 Bowers, L. (1996) Acute Toxicity of (carbon 14)-NTN 33823 to Chironomus tentans Under Static Conditions: Lab Project Number: 107316: N3823302. Unpublished study prepared by Bayer Corp. 30 p. 43946603 Dobbs, M.; Frank, J. (1996) Acute Toxicity of (carbon 14)-NTN 33519 to Hyalella azteca Under Static Conditions: Lab Project Number: 107148: N3823201. Unpublished study prepared by Bayer Corp. 31 p. 43946604 Dobbs, M.; Frank, J. (1996) Acute Toxicity of (carbon 14)-NTN 33519 to Chironomus tentans Under Static Conditions: Lab Project Number: 107311: N3823301. Unpublished study prepared by Bayer Corp. 35 p. 44558901 Bowers, L.; Lam, C. (1998) Acute Toxicity of 6-chloronicotinic acid (a metabolite of Imidacloprid) to Chironomus tentans Under Static Renewal Conditions: Lab Project Number: 96-B-123: 108127. Unpublished study prepared by Bayer Corporation. 24 p. 48077912 Lukancic, S.; Zibrat, U.; Mezek, T.; et al. (2010) Effects Exposing Two Non- Target Crustacean Species, Asellus aquaticus L., and Gammarus fossarum Koch, to Atrazine and Imidacloprid. Bulletin of Environmental Contamination Toxicology 84:85-90.

72-3 Acute Toxicity to Estuarine/Marine Organisms MRID Citation Reference

42055318 Ward, G. (1990) NTN-33893 Technical: Acute Toxicity to Sheepshead Minnow, Cyprinodon variegatus, Under Static Test Conditions: Lab Project Number: J9008023E: 100354. Unpublished study prepared by Toxikon Environmental Sciences. 36 p. 42055319 Ward, S. (1990) NTN-33893 Technical: Acute Toxicity to the Mysid, Mysidopsis bahia, under Flow-Through Test Conditions: Lab Project Number: J9008023B/F: 100355. Unpublished study prepared by Toxikon Environmental Sciences. 46 p. 42256305 Wheat, J.; Ward, S. (1991) NTN 33893 Technical: Acute Effect on New Shell Growth of the Eastern Oyster, Crassostrea virginica: Lab Project Number: J9008023D: J9107005. Unpublished study prepared by Toxikon Environmental Sciences. 54 p. 42528301 Lintott, D. (1992) NTN 33893 (240 FS Formulation): Acute Toxicity to the Mysid, Mysidopsis bahia under Flow-through Conditions: Lab Project Number: J9202001: 103845. Unpublished study prepared by Toxikon

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Environmental Sciences. 43 p.

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study MRID Citation Reference

42055320 Cohle, P.; Bucksath, J. (1991) Early Life Stage Toxicity of NTN 33893 Technical to Rainbow Trout (Oncorhynchus mykiss) in a Flow-through System: Lab Project Number: 38347: 101214. Unpublished study prepared by Analytical Bio-Chemistry Labs., Inc. 8 p. 42055321 Young, B.; Blake, G. (1990) 21-Day Chronic Static Renewal Toxicity of NTN 33893 To Daphnia magna: Lab Project No: 38346: 100247. Unpublished study prepared by Analytical Bio-Chemistry Labs., Inc. 84 p. 42055322 Ward, G. (1991) NTN 33893 Technical: Chronic Toxicity to the Mysid, Mysidopsis bahia, Under Flow-Through Test Conditions: Lab Project Number: J9008023G/H: 101347. Unpublished study prepared by Toxikon Environmental Sciences. 87 p. 42256304 Gagliano, G. (1991) Growth and Survival of the Midge (Chironomus tentans) Exposed to NTN 33893 Technical Under Static Renewal Conditions: Lab Project Number: N3881401: 101985. Unpublished study prepared by Mobay Corp. 43 p. 42480501 Gagliano, G. (1992) Raw Data and Statistical Analysis Supplement for Early Life Stage Toxicity of NTN 33893 to Rainbow Trout (Oncorhynchus mykiss): Lab Project Number: 38347. Unpublished study prepared by ABC Labs, Inc. 292 p.

850.1010 Aquatic invertebrate acute toxicity, test, freshwater daphnids MRID Citation Reference

49626501 McGee, S.; Bowers, L.; Hall, T. (2015) Criteria for Evaluating Mesocosm Studies of Aquatic Invertebrates Exposed to Imidacloprid. Project Number: US0481, 60/80005. Unpublished study prepared by Bayer Crop Science LP. 195p. 49626502 McGee, S.; Bowers, L.; Hall, T. (2015) Criteria for Evaluating Laboratory Studies of Aquatic Invertebrates Exposed to Imidacloprid. Project Number: US0481, 60/80005. Unpublished study prepared by Bayer Crop Science LP. 1334p. 49695201 Goss, G. (2015) Daphnia magna Acute Immobilization Test on VIVE(R) Imidacloprid SC Formulation: VCP-08-A and VCP-08-B. Unpublished study prepared by University of Alberta. 34p.

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850.1400 Fish early-life stage toxicity test MRID Citation Reference

49602703 Gries, T. (2002) Imidacloprid (NTN 33893): Early Life-Stage Toxicity Test with Rainbow Trout (Oncorhynchus mykiss) under Flow-Through Conditions. Project Number: 1022/016/321. Unpublished study prepared by Springborn Smithers Laboratories (Europe) AG. 102p.

890.1350 Fish Short-Term Reproduction MRID Citation Reference

48671403 Banman, C.; Matlock, D.; Lam, C. (2012) Short-Term Reproduction Assay with Fathead Minnow (Pimephales promelas) Exposed to Imidacloprid Technical Under Flow-through Conditions. Project Number: M/428258/01/1/OCR, EBNTY005. Unpublished study prepared by Bayer CropScience and Experimental Pathology Laboratories. 143p.

850.1500 Fish life cycle toxicity MRID Citation Reference

49759105 Oslosky, S. (2015) Waiver Request for Toxicology Preventol TM Insecticide (Additional Source) Imidacloprid. Unpublished study prepared by Lanxess Corporation. 10p.

850.1730 Fish BCF MRID Citation Reference

49759105 Oslosky, S. (2015) Waiver Request for Toxicology Preventol TM Insecticide (Additional Source) Imidacloprid. Unpublished study prepared by Lanxess Corporation. 10p.

850.1950 Field testing for aquatic organisms MRID Citation Reference

47699442 No DER Ratte, H.; Memmert, U. (2003) Biological Effects and Fate of Imidacloprid SL located 200 in Outdoor Microcosm Ponds. Project Number: 811776, M/084035/01/2, 811787. Unpublished study prepared by RCC, Ltd. 455 p. 47699443 No DER Ratte, H.; Memmert, U. (2005) Evaluation of the Report: Biological Effects

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located and Fate of Imidacloprid SL200 in Outdoor Microcosm Ponds. Project Number: 811776, M/251183/01/2. Unpublished study prepared by RCC Umweltchemie Ag and Alterra, Green World Research. 14 p. 49759105 Waiver Oslosky, S. (2015) Waiver Request for Toxicology Preventol TM Insecticide request (Additional Source) Imidacloprid. Unpublished study prepared by Lanxess Corporation. 10p.

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Appendix A: Labeled Use Patterns Tables

Table A-1 contains a list of the crops belonging to listed crop group and subgroup in various imidacloprid labels. Data indicates that imidacloprid can be used in an extensive list of crops that are planted in extensive agricultural land.

Table A-1 Alphabetical order listing of crops belonging to crop groups/subgroups in various labels for the agricultural use patterns Crop Designation Crops Group/Subgroup Bearing fruits Avocado; Citrus (orange, Calamondin, grapefruit, kumquat, lemon, lime, tangerine, and grown in Residential & tangelo); Pecans; Grapes and Pome fruits (Apple, Crabapple, Loquat, Mayhaw, Pear, Oriental Commercial area Pear, Quince); Broccoli, Broccoli raab (rapini), Brussels sprouts, Cabbage, Cauliflower, Cavalo broccoli, Chinese (gai lon) broccoli, Chinese (bok Brassica (Cole) 05 Leafy Vegetables choy) cabbage, Chinese (napa) cabbage, Chinese mustard (gai choy) cabbage, Collards, Kale, Kohlrabi, Mizuna, Mustard greens, Mustard spinach, Rape greens Chive (fresh leaves), Chinese chive (fresh leaves), Daylily (bulb), Elegans hosta, Fritillaria (bulb and leaves), Garlic (common group, great-headed group, serpent group), Kurrat group, Leek group (including common, lady’s and wild), Lily (bulb), Onion (bulb and green leaves Bulb Vegetables 03-07 including: common group, Beltsville bunching, Chinese bulb, fresh, green, macrostem, Pearl group, potato onion group, tree onion-tops, Welsh-tops), Shallot, plus cultivars, varieties, and/ or hybrids of these Bushberry 13-07-B Blueberry, Currant, Elderberry, Gooseberry, Huckleberry, Juneberry, Ligonberry, Salal Blackberry: (Rubus eubatus): bingleberry, black satin berry, boysenberry, Cherokee blackberry, Chesterberry, Cheyenne blackberry, coryberry, darrowberry, dewberry, Dirksen thornless berry, Himalayaberry, hullberry, Lavacaberry, Loganberry, Lowberry, Lucretiaberry, Caneberry 13-07-A mammoth blackberry, Marionberry, Nectarberry, Olallieberry, Oregon evergreen berry, Phenomenalberry, Rangeberry, Ravenberry, Rossberry, Shawnee blackberry, youngberry, and varieties and/or hybrids of these); Raspberry: black and red: Rubus occidentalis, Rubus strigosus, Rubus idaeus Calamondin, Citrus citron, Citrus hybrids (includes chironja, tangelo, and tangor), Grapefruit, Citrus 10 Kumquat, Lemon, Lime, Mandarin (tangerine), Pummelo, Orange (sweet and sour), Satsuma mandarin, and other cultivars and/or hybrids of these Chayote (fruit), Chinese waxgourd (Chinese preserving melon), Citron melon, Cuban pumpkin, Cucumber, Gherkin, Gourd (edible, includes hyotan, cucuzza, hechima, Chinese okra), Momordica spp. (includes balsam apple, balsam pear, bitter melon, Chinese cucumber), Muskmelon (hybrids and/or cultivars of Cucumis melo including true cantaloupe, cantaloupe, Cucurbit casaba, Crenshaw melon, golden pershaw melon, honeydew melon, honey balls, mango melon, 09 Vegetables Persian melon, pineapple melon, Santa Claus melon, snake melon and Winter melon), Pumpkin, Squash (includes summer squash types such as: butternut squash, calabaza, crookneck squash, Hubbard squash, scallop squash, straightneck squash, vegetable marrow and zucchini, and winter squash types such as acorn squash and spaghetti squash), Watermelon (includes hybrids and/or varieties of Citrullus lanatus) Fruiting Eggplant, Ground cherry, Okra, Pepper (including bell, chili, cooking, pimento and sweet) 08 Vegetables Tomato, Pepinos, Tomatillo Grape American bunch grape, Muscadine grape and Vinifera grape Angelica, Balm (lemon balm), Basil (fresh and dried), Borage, Bumet, Camomile, Catnip, Chervil (dried), Chinese chive, Chive, Clary, Coriander (cilantro or Chinese parsley leaves), Herbs & Spices 19-A Costmary, Culantro (leaf), Curry (leaf), Dillweed, Horehound, Hyssop, Lavender, Lemongrass, Lovage (leaf), Marigold, Marjoram, Nasturtium, Parsley (dried), Pennyroyal, Rosemary, Rue, Sage, Savory (summer and winter), Sweet bay (bay leaf), Tansy, Tarragon, Thyme,

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Crop Designation Crops Group/Subgroup Wintergreen, Woodruff, Wormwood. Hops Amaranth (leafy amaranth, Chinese spinach, tampala), Arugula (Roquette), Chervil, Chrysanthemum (edible leaved and garland), Corn salad, Cress (garden), Cress (upland, yellow Leafy Green rocket, winter cress), Dandelion, Dock (sorrel), Endive (escarole), Lettuce (head and leaf), Vegetables, 04-A Orach, Parsley, Purslane (garden and winter), Radicchio (red chicory), Spinach (including New including Zealand and vine (Malabar spinach, Indian spinach)) and Watercress Watercress (commercial production only, applications must not be made to native cress growing in streams or other bodies of water), Watercress (upland) Leafy Petiole Cardoon, Celery, Celtuce, Chinese celery (fresh leaves and stalk only), Florence fennel 04-B Vegetables (including sweet anise, sweet fennel, Finocchio), Rhubarb, Swiss chard Edible Podded and Succulent Shelled Pea and Bean and Dried Shelled Pea and Bean: Bean: Lupinus spp.: grain lupin, sweet lupin, white lupin, and white sweet lupin; Phaseolus spp.: field bean, kidney bean, lima bean, navy bean, pinto bean, runner bean, snap bean, tepary Legume bean, wax bean); and Vigna spp.: adzuki bean, asparagus bean, blackeyed pea, catjang, Chinese Vegetables, 06-C longbean, cowpea, Crowder pea, moth bean, mung bean, rice bean, Southern pea, urd bean, Except Dry yard-long bean; Pea: Pisum spp.: dwarf pea, edible-pod pea, English pea, field pea, garden pea, Soybeans green pea, snow pea, sugar snap pea); Other Beans and Peas: Broad bean (fava), Chickpea (garbanzo bean), Guar, Jackbean, Lablab bean (hyacinth bean), Lentil, Pigeon pea, Soybean (immature seed), Sword bean] Pome Fruits 11 Apple, Crabapple, Loquat, Mayhaw, Pear (including Oriental pear), Quince Beet (garden), Burdock (edible), Carrot, Celeriac, Chervil (turnip-rooted), Chicory, Ginseng, Root Vegetables, 01-B Horseradish, Kava, Parsley (turnip rooted), Parsnip, Radish, Oriental radish (diakon) Rutabaga, Except Sugarbeet Salsify (oyster plant), Salsify (black), Salsify (Spanish), Skirret and Turnip. Apricot, Cherry (including sweet and tart), Nectarine, Peach, Plum (including Chickasaw, Stone Fruits 12 Damson and Japanese), Plumcot, Prune (fresh and dried) Almond, Beechnut, Brazil nut, Butternut, Cashew, Chestnut, Chinquapin, Filbert, Hickory nut, Tree Nuts 14 Macadamia nut, Pecan, Pistachio, Walnut [black and English] Acerola, Atemoya, Avocado, Birida, Black sapote, Canistel, Cherimoya, Custard apple, Feijoa, Jaboticaba, Guava, Llama, Longan, Lychee, Mamey sapote, Mango, Papaya, Passionfruit, Tropical Fruits Persimmon, Pulasan, Rambutan, Sapodilla, Soursop, Spanish lime, Star apple, Starfruit, Sugar apple, Wax jambu Arracacha, Arrowroot, Artichoke (Chinese and Jerusalem), Canna (edible, Queensland Tuberous and 01-C arrowroot), Cassava (bitter & sweet), Chayote (root), Chufa, Dasheen (taro), Ginger, Leren, Corm Vegetables Sweet potato, Tanier (cocoyam), Turmeric, Yam bean (jicama, manoic pea), Yam (true) Crops in red indicate crop exposure scenario selected for modeling.

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Foliar Application

 Table A-2 contains a summary of sample formulations used for foliar applications of imidacloprid. The summary is based on a sample of 14 labels. Data indicate that imidacloprid designated for foliar application appears to be mainly formulated as a flowable/water dispersible granules/powder which is applied as liquid spray. Additionally, the active ingredient in eleven of the examined formulations is imidacloprid alone with concentrations ranging from 16.5 to 75% with three of the formulations containing imidacloprid concentrations ranging from 11 to 21% and one of the following active ingredients: 12% Cyfluthrin, 10.5% β-Cyfluthrin, and 11% Spirotetramat. It is important to note that the summary in Table A-2 is based on examination of most of the current imidacloprid labels (not just those shown the table). This examination was conducted to insure that maximums for the single/seasonal or annual rates, maximum number of applications and minimum application intervals are representative of most current imidacloprid labels;

 Table A-3 contains a summary of the foliar use patterns for imidacloprid. The formulations are applied as a liquid spray that can be applied by ground or air with airblast for tree crops or by chemigation; except grapes and post-harvest application for strawberry. Table A-3 contains the application parameters, and the application window for each crop/crop group/sub-group along with application restrictions related to pollinator production;

 Table A-4 contains restricted period in the foliar application windows for pollinator protection.

Table A-2 A summary of sample formulations used for foliar applications of imidacloprid EPA Reg. Product Name Formulation No. Active Ingredient(s) % ADMIRE ® PRO™ Flowable 264-827 42.8% Imidacloprid alone GAUCHO® 550 SC Insecticide Flowable 264-827 42.8% Imidacloprid alone LEVERAGE® 2.7 Insecticide Suspension Emulsion 264-770 17.0% Imidacloprid + 12.0% Cyfluthrin LEVERAGE® 360 Insecticide Flowable 264-1104 21.0% Imidacloprid + 10.5% β-cyfluthrin MOVENTO® RC Flowable 264-1170 11.0% Imidacloprid + 11.0% Spirotetramat PROVADO 70 WG Wettable Granules 264-823 70.0% Imidacloprid alone PROVADO® PRO Insecticide Flowable 264-858 16.5% Imidacloprid alone Water Soluble PROVADO® Solupak 75% Package 264-761 75.0% Imidacloprid alone ROVADO® 1.6 Flowable 264-763 17.4% Imidacloprid alone AmTide Imidacloprid 75% WDG Water Dispersible Insecticide Granules 83851-7 75.0% Imidacloprid alone Willowood Imidacloprid 4SC flowable 87290-26 40.7% Imidacloprid alone MALLET® 75 WP INSECTICIDE Wettable Powder 228-588 75.0% Imidacloprid alone TR1MAX™ PRO Insecticide Flowable 264-855 40.7% Imidacloprid alone TRIMAX™ Insecticide Flowable 264-783 40.7% Imidacloprid alone

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Table A-3 Foliar use patterns for imidacloprid

1 Application Parameters Application Window (Refer to Use Pattern (Crop Group) MSR MNA MAR MAI Pollinator Statements Number)

Artichoke, Globe 0.125 4 0.500 14 AP up to 7 d. PH

Banana and Plantain 0.100 5 0.500 14 Anytime up to 0 d. PH

Brassica (cole) Vegetables (05) 0.047 5 0.2343 5 Anytime up to 7 d. PH

Bulb Vegetables (3-07) No Foliar Application

Bushberry (13-7-B) 0.100 5 0.500 7 AB up to 3 d. PH (No. 2)

Caneberry (13-A) 0.100 3 0.300 7 AB up to 3 d. PH (No. 2)

Citrus (10) 0.250 2 0.500 10 Anytime up to 0 d. PH (No. 1)

Coffee 0.100 5 0.500 7 Anytime up to 7 d. PH (No. 2)

Cotton 0.062 5 0.310 7 Anytime up to 14 d. PH

Cranberry (13-07-C) No Foliar Application

Cucurbit Vegetables (09) No Foliar Application

Fruiting Vegetables (08) Plus Okra 0.080 3 0.240 5 AP up to 0 d. PH

Grape 0.050 2 0.100 14 Anytime up to 0 d. PH

Herbs & Spices (19-A) 0.043 3 0.1293 5 AP up to 7 d. PH

Hops 0.100 3 0.300 21 Anytime up to 28 d. PH

Leafy Green Vegetables (04-A) 0.047 5 0.2343 5 AP up to 7 d. PH

Leafy Petiole vegetables (04-B) No Foliar Application

Legume Vegetables (6-C), except Soybeans 0.043 3 0.1293 7 AP up to 7 d. PH

Peanuts 0.044 3 0.132 5 Emergence up to 14 d. PH

Pome Fruits (11): Pears 0.250 2 0.500 10 Anytime up to 7 d. PH (No. 2)

Pome Fruits (11): All Others in 11 0.100 5 0.500 10 Anytime up to 7 d. PH (No. 2)

Pomegranate 0.100 3 0.300 7 Anytime up to 7 d. PH (No. 2)

Potato 0.050 4 0.200 7 Emergence up to 7 d. PH

Root Vegetables (01-B) except Sugarbeet 1 0.044 3 0.132 5 AP up to 7 d. PH

Soybeans (06) 0.047 3 0.141 7 GS: V2, R1, and R3 up to 21 d. PH

Stone Fruits (12): Apricot, Nectarine & Peach 0.100 3 0.300 7 Anytime up to 0 d. PH (No. 2)

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1 Application Parameters Application Window (Refer to Use Pattern (Crop Group) MSR MNA MAR MAI Pollinator Statements Number)

Stone Fruits (12): Cherries, Plums, Plumcot, Prune 0.100 5 0.500 10 Anytime up to 7 d. PH (No. 2)

Strawberry 0.047 3 0.1413 5 AP up to 7 d. PH (No. 1)

Sugarbeet No Foliar Application

Tobacco: 0.050 x 5+ 0.030 x 1 5+1 0.280 7 Emergence up to 14 d. PH

Tree nuts (14): 0.101 x 3 + 0.056 x 1 3+1 0.359 6 Anytime up to 7 d. PH (No. 2)

Tropical Fruits 0.100 5 0.500 10 Anytime up to 7 d. PH (No. 2)

Tuberous Corm Vegetables (01-C) 0.044 3 0.1323 5 AP up to 7 d. PH

1 Note: Rate for Radish in Willowood Imidacloprid 4SC (Registration No. 87290-26)= 0.044 x 1= 0.044; Others included in (01-C) 2 Application Parameters: MSR= Max Single Rate; MNA= Max Number of Applications; MAR= Max Annual/Season Rate and MAI= Min Application Intervals in Days noting that rates are in lb. a.i/A. 3 Maximum Rate is seasonal; All others are annual 4 Application Window: AP: After planting; PH: Prior to Harvest; AB: After blooming and GS: Plant Growth Stage Pollinator Statements: No.1= Do not apply within 10 days prior to bloom, during bloom, or when bees are foraging; No.2= Do not apply pre-bloom, during bloom, or when bees are foraging.

Table A-4 Restricted period in the foliar application windows for pollinator protection Crop/Crop Group Name Restricted Application Window Foliar Application

(Crop Group, if any) From To

Bushberry (13-7-B) Pre-bloom: Early April End of bloom: End of May

Caneberry (13-7-A) Pre-bloom: Early April End of bloom: End of May

Citrus (10) 10 d. Pre-bloom: Late February End of bloom: Early April

Coffee Pre-bloom? End of bloom?

Cranberry (13-7-C) No Foliar Application No Foliar Application

Pome Fruits (11) Pre-bloom? End of bloom?

Pomegranate Pre-bloom: Thru June End of bloom?

Stone Fruits (12) Pre-bloom? End of bloom?

Strawberry (FL) 10 d. pre-bloom: Early November End of bloom: Early Dec;

Strawberry (CA) 10 d. pre-bloom: Fall (Oct) End of bloom: Spring (Apr)

Tree nuts (14) Pre-bloom End of bloom

Estimated Window Dates End of April End of May

Tropical Fruits (Avocado) Pre-bloom: Avocado: Mid Mar End of bloom: Mid Apr

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Soil Application

 Table A-5 contains a summary of sample formulations used for soil applications of imidacloprid. The summary is based on a sample of 7 labels. Data indicate that imidacloprid appears to be mainly formulated as a flowable/granular insecticide which is applied as liquid spray in case of liquid flowable formulations or in-band/furrow in case of granular formulations. Additionally, the active ingredient in six of the examined formulations is imidacloprid alone with concentrations ranging from 2.5 to 42.8% and one formulation containing imidacloprid concentration of 22.2% with 15.4% fluopyram. It is important to note that the summary in Table A-5 is based on examination of most of the current imidacloprid labels (not just those shown in the table). This examination was conducted to insure that maximums for the single/seasonal or annual rates, maximum number of applications and minimum application intervals are representative of most current imidacloprid labels;

 Table A-6 contains a summary of the soil use patterns for imidacloprid. The formulations are applied either as liquid or granules. Only one single application is labeled for each of the crop groups/subgroups or crops ranging from 0.18 to 0.50 lbs. a.i./A/season or year. Ground application is used to deliver imidacloprid formulation into the soil as a liquid spray or granular broadcast. Additionally, chemigation may also be used for liquid formulations to deliver the pesticide into the soil. All of the soil application procedures are used to place the pesticide below the soil-surface and into the seed or root zone of the crop. In order to achieve this placement into the proper depth, more than one method may be used depending on the crop being treated;

 Table A-7 contains a summary of methods used for applying liquid sprays to soil using ground equipment. Application information for liquid spray indicate that imidacloprid may be sprayed into the soil, by ground equipment, in band followed by operations to place the pesticide below the soil surface at a depth approximating crop seeding depth/root zone. This application appears to be either at/or just before seeding. Soil application by liquid spray is not expected to produce significant drift when directed into the bottom of the furrow opening as it is usually done by a jet spray that is adsorbed by the soil in the bottom of the furrow and is immediately followed by burial with dry soil. However, drift is expected from application to the soil surface just before incorporation. In both cases, placement of the pesticide below the soil surface is expected to reduce the amount of run-off estimated by modeling when the pesticide is placed below the 2 cm run-off extraction zone of the model. When the chemical is drenched, injected or applied by chemigation, no drift is expected although part of the chemical may be, partially, subject to run-off depending on the expected distribution of the chemical in the soil profile. The distribution of the chemical with depth in the soil profile will depend on many factors including those associated with the chemical (e.g., solubility and mobility); volume of water used to drive the chemical into the desired depth (e.g., volume of water used in chemigation, drenching and or in watering-in); soil permeability, soil moisture content/distribution with depth; and timing of application in relation to precipitation (volume/intensity) and/or irrigation. In order to achieve accurate placement of the pesticide at depth, labels for imidacloprid stress that the objective, for any of the soil application procedures, is to place or drive the product into the root zone. Having the pesticide in the root zone will make it available for upward xylem translocation into the plant foliage. To achieve this, 142

labels suggest to physically place the pesticide at the desirable depth by the application method such as injection or using high drench volumes, application just before expected rain, or irrigation just after application among many others;

 Table A-8 contains a summary of methods/timing used for soil application of granular formulations (e.g., ADMIRE 2.5 Granular) to soil using ground equipment. Based on the granular formulation and the required incorporation to depths >1”, drift and presence of the granules in the soil run-off extraction zone are expected to be limited.

 Table A-9 contains a summary of soil application timing for the various use patterns of imidacloprid;

 Table A-10 contains restricted period in the soil application windows for pollinator protection.

Table A-5 A summary of sample formulations used for soil applications of imidacloprid EPA Reg. Product Name Formulation Active Ingredient(s) % No. Admire® 2 Flowable Insecticide Flowable 264-758 21.4% Imidacloprid alone ADMIRE 2.5 Granular Granules 3125-423 2.5% Imidacloprid alone ADMIRE ™ ® PRO Flowable 264-827 42.8% Imidacloprid alone GAUCHO® 550 SC Insecticide Flowable 264-827 42.8% Imidacloprid alone TRIMAX™ Insecticide Flowable 264-783 40.7% Imidacloprid alone VELUM™ TOTAL Flowable 264-1171 22.2% Imidacloprid + 15.4% Fluopyram Willowood Imidacloprid 4SC flowable 87290-26 40.7% Imidacloprid alone

Table A-6 Soil use patterns for imidacloprid

Use Pattern Crop (Crop Group) MSR 1 Artichoke, Globe; Banana and Plantain; Bulb Vegetables (03-07-A); Bushberry (13-07-B); Caneberry (13-07-A); Citrus (10): Field; Coffee; Cranberry (13-07-C); Fruiting Vegetables (08): Pepper & Okra; Grape; Pomegranate; 0.50 Strawberry: Annual During Transplant or for established crop* & Perennial @ Spring before bud opening; Tree Nuts (14); and Tropical Fruits Tobacco Applied 0.043 x 11= 0.473 Plus 1 x 0.027 (Twelve Applications) with 7 days’ intervals 0.50 Brassica (cole) Vegetables (05); Cucurbit Vegetables (09)2; Fruiting Vegetables (08): Eggplant & Tomato; Herbs & Spices (19-A); Leafy Green Vegetables (04-A); Leafy Petiole Vegetable(04-B)2; Legume Vegetables, except Peanuts; 0.38 Pome Fruits (11); Root Vegetables except Sugarbeet (01-B); Soybeans(06-C); Stone Fruits (12); Strawberry (13): Perennial @ Post Harvest; Tuberous & Corm Vegetables (01-C); Watercress (Included with Leafy Green vegetables) Cotton 0.33 Potato 0.31 Hops 0.30 Sugarbeet (CA only) 0.18 1 MSR= Maximum Single rate in lb. a.i/A/Year * No application immediately prior to bud opening or during bloom Per Season: Root Vegetables except Sugarbeet (01-B); Tuberous & Corm Vegetables (01-C); Bulb Vegetables (03-07-A); Leafy Green Vegetables (04-A); Brassica (cole) Vegetables (05); Legume Vegetables, except Soybeans(06-C); Fruiting Vegetables (08): Pepper & Okra; Strawberry; Herbs 2 Maximum Rate for these two crop groups are seasonal; All others are annual

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Table A-7 Ground soil application methods for liquid sprays (No soil use for soybeans)

Crop/Crop group/subgroup Method1 Crop/Crop group/subgroup Method1 Artichoke (Globe) 1a & 7a Leafy Petiole vegetables (04-B) = Brassica Banana & Plantain 7a Legume Vegetables (06), except Soybeans = Brassica Brassica (Cole) Vegetables (05) 1a, 2, 3, 4a, 6a & 7a Peanut 1a & 7a Bulb Vegetables (03-07) 1a, 2, 6 & 7a Pome Fruits (11) 7a Bushberry (13-07-C) 7a & 8b Pomegranate 7a Caneberry (13-07-A) 6c & 7a Potatoes 1a, 2, 3, 4a & 7a Citrus (10) 7c, 6b, 8a, 12 & 13 Root Vegetables (01-B), except Sugarbeet 1a, 2, 5 & 7a Coffee 4b, 6b & 7a Stone Fruits (12) 7a Cotton 1a, 2 & 7a Strawberry: Annual & Perennial 7b, 9a, 9b & 14 Cranberry (13-07-B) 7b & 10 Strawberry: Perennial @ Post Harvest 7b, 9b Cucurbit Vegetables (09) = Brassica Sugarbeet 1d Fruiting Vegetables (08) + Okra = Brassica Tobacco 1, 4a & 7a Grape 4b, 6a, 7 & 16 Tree Nuts (14) 4b, 7a, 12 & 14 Herbs & spices (19-A) 1b, 5, 6a & 7a Tropical Fruits 7a Hops 1a, 4b, 6a & 7a Tuberous and Corm Vegetables (01-C) 1c, 5 & 11 Leafy Green vegetables (04-A) = Brassica Watercress = Brassica 1 Descriptions of the Methods: (1) In-furrow spray directed on or below seed: (a) During bedding; (b) During setting or transplant; (c) Over Hulis (plant material); and (d) During bedding immediately prior to planting or at the time of planting; (2) Narrow Band Spray (≤2”) directly below the eventual seed row during bedding Or over the seed-line incorporated to 1-2” by irrigation; (3) Narrow Band Spray directly over the raw covered with ≥ 3” of soil during Hilling; (4) Subsurface side-dress: (a) Sprayed on both sides of the row covered with ≥ 3” of soil or incorporated into the root-zone; and (b) Shanked/Injected on both sides of plants/ trees followed by irrigation within 48 hours; (5) Shanked-in 1 to 2” below seed depth; seed-line; or below Hulis; (6) Drench: (a) Transplant stage: Transplant water drench Or After transplant/seeding: Seeding or Hill drench; (b) For Trees: Basal soil drench into the base/around trees in sufficient water to insure incorporation into the entire root-zone followed by irrigation; and (c) For Caneberry: With 500 gal. solution/A; and (7) Chemigation into root-zone through low-pressure drip or trickle irrigation: (a) irrigation not specified; (b) With 600 to 1,000 gallons of water followed by 0.1 to 0.3” irrigation within 24 hours; and (c) On wetted soil followed by 10-20 minutes of additional irrigation. (8) Soil surface spray in bands:(a) On both sides of the tree within the drip-line area of the tree followed immediately with light sprinkler irrigation into the upper portion of the root-zone; and (b) On both sides of the row (18” band) to moist soil followed immediately by 0.5 to 1” of irrigation/rainfall within 24 hours; (9) Soil-surface applications in a minimum of 20 gallons of water/A followed by 0.25” of rainfall or irrigation water/A within 2 hours of application to incorporate product into root-zone: (a) Over-the-row band spray in Annual or Perennial crops; or (b) Raw band spray with width= width of anticipated fruiting bed in Perennial crops (10) Soil Surface spray Directed to the root and crown area with high volume of spray (20 gal) (11) Side-dress no later than 45 days after-planting; (12) High-volume basal drench to slightly moist soil surrounding the tree trunk. Applied in sufficient volume to penetrate the soil to a depth of 18 – 24” (for Termite control); (13) Low-pressure chemigation or Soil surface band spray with irrigation to ensure complete coverage of the root system (Nematode suppression); (14) Emitter or spot application in a minimum of 4 fluid ounces of mixture per emitter site; (15) Plant-material or plant-hole treatment (just prior to, or during transplanting); and (16) Applied by Chemigation or the French plow technique followed immediately by sufficient irrigation to move the product into the entire root-zone of the plant (Nematode suppression)

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Table A-8 Ground soil application methods/timing for granular formulations (Application rates are the same as liquid formulations)

Crop/Crop Method group/subgroup (a) In a narrow 2” band centered on the plant row 1 to 2” below the seed depth during bedding <14 days before planting;

Brassica (cole)/fruiting (b) In furrow application at or below seed level during planting; or vegetables

(c) As a side-dress placed 2-4” at the side of each row and incorporated at a depth of >1” after the plants are established (a) In a narrow 2” band centered on the plant row 1 to 2” below the seed depth Lettuce (head & leaf; during bedding <14 days before planting; direct seeded or

transplanted) (b) In furrow application at or below seed level during planting;

Table A-9 Soil application timing for the various use patterns of imidacloprid

Timing1 Crop (s)/Crop Group(s)

Artichoke (Globe) (X= 7); Bulb Vegetables (03-07) (X= 21); and Prior to; at or after planting up to X days prior to harvest Strawberry: Annual & Perennial (X= 14)

Prior to or at planting Sugarbeet

Prior to or at planting up to 14 days prior to harvest Tobacco

At planting Cotton; Peanut; and Potatoes

At or immediately after planting up to 21 days prior to Fruiting Vegetables (08) + Okra harvest

At planting up to 21 days prior to harvest Cucurbit Vegetables (09)

Brassica (Cole) Vegetables (05) (X= 21); Herbs & spices (19-A) (X= 14); Leafy Green vegetables (04-A) (X= 21);

Leafy Petiole vegetables (04-B) (X= 45); Legume Vegetables (06), At or after planting up to X days prior to harvest except Soybeans (X= 21); Root Vegetables (01-B), except Sugarbeet (X= 21); Tuberous and Corm Vegetables (01-C): Corm (X= 125); Tuberous and Corm Vegetables (01-C): Leaves (X= 3); and Watercress (X= 21)

Banana & Plantain (X= 0); Citrus (10) (X= 0); Coffee (X= 7); Cranberry (13-07-B) (X= 30); Grape (X= 30);

Anytime up to X days prior to harvest Hops (X= 60); Pome Fruits (11) (X= 21); Pomegranate (X= 0); Stone Fruits (12) (X= 21); Tree Nuts (14) (X= 7); and

Tropical Fruits (X= 6)

During renovation up to 14 days prior to harvest Strawberry: Perennial @ Post Harvest

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Timing1 Crop (s)/Crop Group(s)

After bloom up to 7 days prior to harvest Bushberry (13-07-C) and Caneberry (13-07-A)

1 X days: The value of X is stated in the second column as it varies with the use pattern

Table A-10 Restricted period in the soil application windows for pollinator protection

Crop/Crop Group Name Restricted Application Window Foliar Application

(Crop Group, if any) From To

Bushberry (13-7-B) Pre-bloom: Early April End of bloom: End of May

Caneberry (13-7-A) Pre-bloom: Early April End of bloom: End of May

Citrus (10) Pre-bloom: Early March End of bloom: Early April

Coffee Pre-bloom: Early March End of bloom: End of May

Cranberry (13-7-C) Just before pre-bloom: Mid-May End of bloom: Mid July

Pome Fruits (11) Pre-bloom: Mid-March End of bloom: Mid May

Pomegranate Pre-bloom: Mid-May End of bloom?

Stone Fruits (12) Pre-bloom: Early April End of bloom: Early May

Strawberry Just before bud opening: Several Weeks? End of bloom?

Tree nuts (14) Pre-bloom? End of bloom?

Tropical Fruits Pre-bloom? End of bloom?

References URLs: https://extension.umaine.edu/blueberries/factsheets/integrated-crop-management/integrated-crop-managment-field- scouting-guide-for-lowbush-blueberries/

http://pestmanagement.rutgers.edu/njinpas/CropProfiles/cranberryprofile.pdf http://www.cranberries.org/cranberries/grow_fall.html http://www.stemilt.com/farm-fork/apples/apple-season-begins/ http://ucanr.edu/sites/Pomegranates/files/166141.pdf http://irrec.ifas.ufl.edu/flcitrus/pdfs/short_course_and_workshop/citrus_flowering/Krezdorn-Flowering_and_Fruit_Set.pdf http://www.gardening.cornell.edu/fruit/homefruit/5strawberries.pdf

Seed Treatment Application

 Table A-11 contains a summary of sample formulations used for seed treatment of imidacloprid. The summary is based on a sample of 12 labels. Data indicate that imidacloprid products, for seed treatment, appear to be mainly formulated as flowable or dust. Additionally, the active ingredient in half of the examined formulations is imidacloprid alone with concentrations ranging from 16.5 to 75% with the other half of the formulations containing 11 to 21% imidacloprid with one or more than one of the following active ingredients: 24% Thiodicarb, 0.415% Tebuconazole, 0.560%

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Metalaxyl, 0.965% Imazalil, 19.55% captan, 20% carboxin, 1% Metalaxyl, and 56.25% Clothianidin. It is also noted that seed treatment labels have other precautionary/restrictive statements that will be considered in this risk assessment (refer to statements 1 to 4 in Table A-11). These statements are related to: covering/incorporation of spilled treated seeds (statement 1 in 11 of 12 labels); prohibition of the use of planter (hopper) box treatment (statement 2 in 6 of 12 labels); giving the maximum rate for the combined seed/foliar/soil treatments (statement 3 in 4 of 12 labels); and specifying the planting depth (statement 4 in 11 of 12 labels); noting that none of these precautionary statements were present in one of the labels (IMIDACLOPRID-METALAXYL product).

 Table A-12 contains a summary of the seed treatment use patterns for imidacloprid. With the exception of a list of crops under the name “seed & pod vegetables”, only one single seed treatment is labeled for individual crops not for the whole crop groups/subgroups. The list of the “seed & pod vegetables” crops are presented in the bottom of Table A-11 and it includes beans and peas among many other crops;

 Table A-13 contains a summary of the special kinds of imidacloprid use patterns for treatments of seed pieces, seedlings, containerized plants and cuttings and whips use patterns. Data in Table A- 13 suggest that imidacloprid applied to potato seed pieces, seedlings of tobacco, cucurbit/ fruiting vegetables and polar/cottonwood cutting/whips may be considered as application to soil because the pesticide is transferred to soil with the plant or the planting media. Calculated application rates are as follows:

o For potato: One application of 0.310 lb. a.i/A/Year at planting; noting that the rate was capped to the maximum stated in the label; o For tobacco: Two application of 0.250 lb. a.i/A/Year with the 1st at planting followed by the 2nd with 7-d interval; noting that the rate was capped to the maximum of 0.5 lb. a.i/A stated in the label; o For cucurbits: Two application of 0.0204 lb. a.i/A/Year with the 1st at planting followed by the 2nd with a 7-d interval noting that the rate is less than the maximum of 0.38 lb. a.i/A stated in the label; o For fruiting vegetables: Two application of 0.190 lb. a.i/A/Year with the 1st at planting followed by the 2nd with a 7-d interval noting that the rate was capped to the maximum of 0.38 lb. a.i/A stated in the label; and o For citrus: Two application of 0.120 lb. a.i/A/Year with the 1st at planting followed by the 2nd with a 14-d interval; rate is less than the maximum of 0.50 lb. a.i/A stated in the label.

 Figure A-1 contains a summary of formulations/procedures used for seed treatment of crops. Imidacloprid labels describe three procedures that may be used for seed treatment which appears to be dependent on the pesticide formulation as well as the type of seeds to be treated. As shown in Figure A-1, seeds may be treated in commercial seed facilities, at agricultural facilities or by the farmer. At commercial facilities, both liquid and dust formulations are used as slurry to coat seeds with the pesticide in a way that would withstand bagging/storage and transport to farmers during the planting season. In this case, the pesticide coating would probably be made somewhat resistance to abrasion although bagging/storage and transport would probably make the coating

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somewhat less resistant to abrasion later at planting. At the agricultural facilities, seeds are treated using stand-alone seed treaters with slurry of either liquid or dust formulations possibly similar to commercial facilities. However, in this case, seeds will be treated just before planting suggesting that abrasion during seeding would probably be lower. Treatment of the seeds, by the farmer, using hopper-box, slurry-box, or other seed treatment applications at, or immediately before, planting is expected to reduce the formation of seed coat dust, at planting, when liquid formulations or slurry are used in the treatment. This is because treated seeds are drilled immediately following treatment. Significant dusting-out is of concern when dust formulations are used as a dry mixture in the planter box for seed treatment prior to planting. In this case, high potential of dusting-off are expected causing on-site and to a lesser extent off-site exposure from the dust formulation. The same is expected to occur even from coated seeds due to abrasion before/during planting. The highest exposure is expected from farmer treatments of barley and wheat with dust formulations of Enhance® AW and Enhance® Plus; bean and peas with dust formulation of Enhance® Plus; and corn (field, pop & sweet), sorghum, and soybeans with dust formulation of Sepresto 75 WS (refer to red boxes in the columns designated for dust formulations 1, 2 and 5 in Figure A-1).

Dust drifting was recognized in only one of the examined twelve imidacloprid seed treatment label. For SENATOR® 600 FS label, the following precautionary statement was included: “Pollinator Precautions: Imidacloprid is highly toxic to bees. Ensure that planting equipment is functioning properly in accordance with manufacturer specifications to minimize seed coat abrasion during planting to reduce dust which can drift to blooming crops or weeds”.

It was reported that variable planter dust emissions were observed during planting corn seeds treated with thiamethoxam or clothianidin. As much as 9 ng a.i/cm2 of clothianidin or thiamethoxam deposited on slides that were placed in the field (Harold Watters, Ohio State Extension, Personal communication). This mass of a.i of the pesticide translates into 0.80% of the active ingredient coating present in the total corn seeds needed to plant one acre. This amount of dusting was obtained from commercially pre-coated seeds and much higher dusting is expected when a dust formulation is used in the planter box. With commercially pre-coated seeds, dusting-off will depend on many factors such as: the strength of the coating (material, thickness), seed surface characteristics, weather conditions, and type and speed of the planter.

Table A-11 A summary of most seed treatment formulations of imidacloprid Restrictions (Statement Formulation Product Name Reg. No. Active Ingredient(s) State No.)1

1, 2, 3 (For soybean: not AERIS® 264-1057 24% Thiodicarb + 24% IMI Liquid >0.38 a.i for seed treatment) & 4

Gaucho® 480 Flowable 264-957 40.7% IMI Liquid 1 & 3 for cotton only

GAUCHO® XT Flowable 264-971 12.70% IMI Liquid 1

GAUCHO® 600 Flowable 264-968 48.70% IMI Liquid 1

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Restrictions (Statement Formulation Product Name Reg. No. Active Ingredient(s) State No.)1

1.384% IMI + Tebuconazole 0.415% + RAXIL® MD EXTRA W 264-997 Liquid 1 & 2 Metalaxyl 0.560%+ Imazalil 0.965%

SENATOR® 600 FS 228-522 48.7% IMI Liquid 1, 2, 3 & 4

19.55% captan + 20% carboxin + 20% Enhance® AW 400-567 Dust 1 IMI

19.55% captan + 20% carboxin + 4% Enhance® Plus 400-568 Dust 1 IMI

Gaucho® 75 ST 264-959 75% IMI Dust 1 & 2

42750- IMIDACLOPRID 75 ST 75% IMI Dust 1 & 2 121

IMIDACLOPRID-METALAXYL 264-1044 25% IMI + 1% Metalaxyl Dust None of the statements

Sepresto 75 WS 264-1081 56.25% Clothianidin + 18.75% IMI Dust 1, 2 & 3

1 Restrictions: Statement 1: Exposed treated seed may be hazardous to birds. Cover or incorporate spilled treated seed; Statement 2: DO NOT use as a planter (hopper) box treatment; Statement 3: The maximum application rate (including seed treatment, foliar application, and soil application) per acre per calendar year for imidacloprid is 0.5 lbs.; Statement 4: Treated seed must be planted into the soil at a depth greater than 1 inch;

Table A-12 Summary of labeled application rates for imidacloprid seed treatment use

Application Rate Calculation in lbs. a.i./Acre1 Use Patterns for Individual Crops; One A= lb. a.i/One seed B= No. of Seeds A x B Crop Group) Or One lb. of Seed Or lb. of Seeds/A Rate ( lb. a.i/A)

Barley 9.375E-04 138.30 0.130

Beans2 1.252E-03 435.60 0.545

Borage3 1.000E-02 15.20 0.152

Broccoli 8.750E-07 210,845 0.184

Buckwheat 2.344E-04 72.00 0.017

Canola/Rape 1.000E-02 8.23 0.082

Carrot 4.922E-08 2,090,880 0.103

Corn, field 4.219E-03 29.57 0.125

Corn, pop 2.500E-03 22.04 0.055

Corn, sweet 2.498E-03 33.19 0.083

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Application Rate Calculation in lbs. a.i./Acre1 Use Patterns for Individual Crops; One A= lb. a.i/One seed B= No. of Seeds A x B Crop Group) Or One lb. of Seed Or lb. of Seeds/A Rate ( lb. a.i/A)

Cotton 5.025E-03 18.89 0.095

Crambe4 1.000E-02 20.00 0.200

Flax5 1.000E-02 45.00 0.450

Leeks 1.477E-07 1,229,929 0.182

Millet 2.500E-03 30.00 0.075

Mustard 1.000E-02 7.00 0.07

Oats 9.375E-04 90.00 0.084

Onions 1.289E-07 1,229,929 0.159

Peanuts 6.234E-04 228.26 0.142

Peas2 1.252E-03 384.07 0.481

Potato 1.260E-04 34,848 0.878

Rye 9.375E-04 109.00 0.102

Safflower 5.000E-03 35.00 0.175

Sorghum 2.484E-03 9.1 0.023

Soybean 1.252E-03 166.67 0.209

Sugar beet 9.035E-02 4.75 0.429

Sunflower 1.103E-06 25,000 0.028

Teosinte 6 2.344E-04 10 0.002

Triticale 9.375E-04 109.00 0.102

Wheat 9.375E-04 156.00 0.146

1 Application Rate Calculation in lbs. a.i./Acre is calculated by multiplying lbs. a.i/One seed by the No. of seeds needed to seed one acre OR by multiplying lbs. a.i/One lb. of seed by the lbs. of seeds needed to seed one acre (values in Black). Data for the active ingredient is taken from the label while that for the seeding rate given by BEAD (Acres Planted per Day and Seeding Rates of Crops Grown in the United States; US EPA, March 24, 2011).

2 Beans and Peas rate are equal to the seed & Pod Vegetables rate of the following crops: Adzuki Bean, Asparagus Bean, Broad Bean (Succulent or Dry), Catjang Bean, Chinese Long bean, Field Bean, Guar Bean, Jack bean, Kidney Bean, Lablab Bean, Lima Bean (Succulent or Dry), Moth Bean (Succulent or Dry), Mung Bean, Navy Bean, Pinto Bean, Rice Bean, Runner Bean, Snap Bean, Sword Bean, Tepary Bean, Urd Bean, Wax Bean, Yard long Bean, Black-eyed Pea (Succulent or Dry), Chickpea, Cowpea (Succulent or Dry), Crowder Pea, Dwarf Pea, Edible-Pod Pea, English Pea, Field Pea, Garden Pea, Green Pea, Pigeon Pea (Succulent or Dry}, Snow Pea, Southern Pea (Succulent or Dry), Sugar Snap Pea, Grain Lupin, Sweet Lupin, White Lupin, White Sweet Lupin, Lentil.

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Application Rate Calculation in lbs. a.i./Acre1 Use Patterns for Individual Crops; One A= lb. a.i/One seed B= No. of Seeds A x B Crop Group) Or One lb. of Seed Or lb. of Seeds/A Rate ( lb. a.i/A)

3 Borage: (SR= 15.2 lbs. seeds/Acre) URL: https://hort.purdue.edu/newcrop/ncnu02/v5-497.html & http://www.harvesttotable.com/2009/04/how_to_grow_borage/ 4 Crambe Seeding rate (SR) URL: https://www.ag.ndsu.edu/pubs/plantsci/crops/a1010.pdf; 5 Flax seeding rate URL: https://www.ag.ndsu.edu/pubs/plantsci/crops/a1038.pdf; 6 Teosinte=10 lbs. seeds/A: http://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/flpmcrb0323.pdf

Table A-13 A Summary for the special treatments with imidacloprid insecticide for seed pieces, seedlings, containerized plants and cuttings and whips1 Treatment Crop Treatment Timing/Procedure Maximum Application Rate For Yearly rate: 0.31 lb. a.i./A/Year Seed pieces are sprayed with a 0.252 lb. a.i./A (one Application) diluted spray of the formulation. Potatoes 2 Seed pieces (Based on 2,000 lbs. of seed pieces needed to Fungicidal or inert absorbent dust plant one acre; Rate per BEAD is much higher may then be applied as it is equal to 34,848 lbs. seed/A) (1) In Nursery, pre-plant in trays: 0.274 lb. a.i/A x 2 “two applications”, 7-d Foliar spray followed by foliar wash- interval) (Based on a the maximum of 0.044 lb. off into the potting media by a.i/1,000 plants in 2 applications) irrigation. 7-days before planting; Should be= 0.250 x two applications= 0.50; and Other given rates (different labels): Tobacco 3 Seedlings (2) In field, during transplant: In- 0.018 and 0.044 lb. a.i/1,000 seedling (Rate is furrow spray; transplant water for nursery and field) drench; Or chemigation into root Pot media is to be transferred into the field with zone seedlings. Treatment (1) & (2) may be Combined Rate with soil: 0.50 lb. a.i./A/Year combined For Squash= 0.0204 lb. a.i/A x 2= 0.0408 “two (1) In Nursery, pre-plant in trays: applications”, 7-d interval) 7-days before planting use foliar

spray followed by foliar wash-off Cucurbit Vegetables For Tomato= 0.204 lb. a.i/A x 2= 0.408 “two into soil by irrigation without loss of (09) applications”, 7-d interval). Seedlings gravitational water or by and Fruiting Should be= 0.19 x two applications= 0.38; Chemigation (direct injection into Vegetables (08)4 (Based on: “0.0156 x 2” lb. a.i/10,000 plants) the overhead irrigation system). And Media, from nursery, is to be transferred into (2) In field: A second application the field with seedlings. within two weeks of transplanting Combined Rate with soil: 0.38 lb. a.i./A/Year (1) In Nursery: 7-days before 0.120 lb. a.i/A x 2= 0.240 “two applications” planting: Either (a) To soil media with no interval specified; Assume 14-d) in pot containing plants distant for (Based on the maximum of 0.000613) the field: Applied as soil drench Other given rates (different labels): Containerized uniformly distributed in the media (a) 0.000132; 0.000365; 0.000608; and Citrus 5 plants without loss of gravitational water or 0.000613 lb. a.i/pot media or one plant by (b) chemigation and/or (c) lb. a.i/pot media or one plant (2) In field: Chemigation into the Media, from nursery, is to be transferred into root zone or Basal soil drench during the field. transplant Combined Rate with soil: 0.50 lb. a.i./A/Year Root Dip just before planting: by soaking roots to slightly above graft in a 10-gallon Stone Fruits solution (0.00313 lb./gal) of the product for five minutes. Then allow to dry/transplant Poplar/Cottonwood Cuttings & A 24-hour Soak to be absorbed by the plant material 151

Treatment Crop Treatment Timing/Procedure Maximum Application Rate For Whips (1) Before cold storage for freshly cut plant material that would be planted later, or (2) After cold storage for plant material and just before planting 0.50 lb. a.i./A= The maximum allowed before planting 1 Examined labels include: Admire® 2 Flowable Insecticide; ADMIRE ™ ® PRO; GAUCHO® 550 SC Insecticide; TRIMAX™; and Willowood Imidacloprid 4SC Insecticide (refer to Table 4, above, for information on these formulations); 2 Calculated acre rate for Potato = >4 lb. a.i/A based on BEAD seeding rate of 34,848 lbs. seed/A. Applied as a Uniform Tray drench (broadcast foliar spray to seedlings in trays) not more than 7 days prior to transplanting followed immediately by overhead irrigation to wash the pesticide from foliage into potting media. At transplanting, transplants must be handled carefully during setting to avoid dislodging treated potting media from roots 3 Calculated acre rate for Tobacco= 0.274 lb. a.i/A x 2 based on 6,233 plants/A, URL: http://tobaccoinfo.utk.edu/pdfs/2003burleyprodguide/filesprior2003/chapter8-lastupdated2002.pdf 4 Calculated acre rate for Squash= 0.0204 lb. a.i/A x 2 = 0.04808 based on 15,374 plants/A (BEAD); Tomato= 0.2040 lb. a.i/A x 2 = 0.40800 (>0.38) based on 130,680 plants/A (BEAD) 5 Calculated acre rate for citrus is based on reported tree density of 194 Trees/Acre, URL: https://edis.ifas.ufl.edu/pi036

Figure A-1 A summary for formulations/procedures used for seed treatment of crops (Refer to legend)

Liquid Formulations1 Dust Formulations2

Crop 1 2 3 4 5 6 1 2 3 4 5 6

Barley

Beans

Broccoli

Buckwheat

Canola/Rape

Carrot

Corn, field

Corn, pop

Corn, sweet

Cotton

Flax, Crambe & Borage

Leeks

Millet

Mustard

Oats

Onions & Leek

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Liquid Formulations1 Dust Formulations2

Crop 1 2 3 4 5 6 1 2 3 4 5 6

Peanuts

Peas

Potato

Rye

Safflower

Seed & Pod Vegetables

Sorghum

Soybean

Sugar beet

Sunflower

Teosinte

Triticale

Wheat

1 Liquid Formulations: 1= AERIS® Seed-Applied Insecticide/Nematicide; 2= Gaucho® 480 Flowable; 3= GAUCHO® XT Flowable; 4= GAUCHO®600 Flowable; 5= RAXIL® MD EXTRA W Seed Treatment; 6= SENATOR® 600 FS;

2 Dust Formulations: 1= Enhance® AW; 2= Enhance® Plus; 3= Gaucho® 75 ST Insecticide; 4= IMIDACLOPRID 75 ST; 5= IMIDACLOPRID- METALAXYL Seed Treatment; 6= Sepresto 75 WS.

Seed Treatment Procedures (At least two procedures were listed for each crop)

Commercial Seed Treatment Facilities Agricultural Establishments Planter box

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Non-Agricultural Use Patterns

(1) Turf & Ornamentals in Nurseries and Residential/Commercial Areas

(a) Soil Applied Granules/Tablets: Most labels for this use pattern were examined to obtain application information (Table A-14). All formulations in Table A-11 are granular except of Merit® FXT Tablet insecticide, which is formulated as tablet with 20% imidacloprid.

Table A-14 Summary of non-agricultural granular/tablet soil applied imidacloprid (IMI) formulations EPA Active Ingredient(s) Product Name Reg. No. IMI % Others 0.15% Imidacloprid + 0.05% Beta-Cyfluthrin Granular Insecticide 72155-31 0.150% 0.05% β-Cyfluthrin ALLECTUS® 0.15 G Plus Turf Fertilizer Insecticide 432-1419 0.083% 0.067% Bifenthrin ALLECTUS® GC Granular Insecticide 432-1416 0.200% 0.16% Bifenthrin ALLECTUS® G Insecticide 432-1407 0.200% 0.16% Bifenthrin Allectus 0.15 GC Plus Turf Fertilizer Insecticide 432-1428 0.083% 0.067% Bifenthrin ALLECTUS® 0.18 G PLUS TURF FERTILIZER Insecticide 432-1418 0.100% 0.08% Bifenthrin Allectus 0.18 GC Plus Turf Fertilizer Insecticide 432-1426 0.100% 0.08% Bifenthrin Allectus 0.225 GC Plus Turf Fertilizer Insecticide 432-1427 0.125% 0.10% Bifenthrin Allectus 0.225 G Plus Turf Fertilizer Insecticide 432-1417 0.125% 0.10% Bifenthrin Bayer Advanced 2-in-1 Rose & Flower Care Ready-to-use Granules III 72155-95 0.220% 0.10% Clothianidin 1.06% Tebuconazole Bayer Advanced All-in -one Rose & Flower Care Ready-to-use G 72155-94 0.110% 0.05% Clothianidin Bayer Advanced 12-Month Tree & Shrub Protect & Feed Ready-To-Use Granules II 72155-96 0.550% 0.275% Clothianidin IMI 0.22 G T&O Insecticide 53883-226 0.220% None IMI 0.3 G Lawn and Ornamental Insecticide 53883-219 0.300% None IMI 1% G Insecticide 53883-227 1.000% None IMI 0.5 G Insecticide 53883-199 0.500% None IMI O.22G RTS GRANULES Ready-to-Spread 53883-256 0.220% None IMI Termite G (0.5%) 53883-198 0.500% None IMI-Lambda G insect Granules 53883-230 0.500% 0.10% λ-Cyhalothrin Imidacloprid 0.2% Insecticide plus Turf Fertilizer 1381-223 0.200% None Imidacloprid 0.5 G - Turf Insecticide 1381-224 0.500% None IMID-BIFEN 0.15 LAWN + FERTILIZER Insecticide 42750-156 0.083% 0.067% Bifenthrin IMID-BIFEN 0.225 LAWN + FERTILIZER Insecticide 42750-162 0.125% 0.10% Bifenthrin IMID-BIFEN 0.36 GC Insecticide 42750-161 0.200% 0.16% Bifenthrin ImiBloc 0.5 G Termiticide Insecticide 70506-143 0.500% None LADA 0.5G Turf and Ornamental Insecticide 83100-14 0.500% None LADA 1.0 G Nursery Insecticide 83100-17 1.000% None LADA 2.S G Ornamental Insecticide 83100-16 2.500% None LADATM O.5G Termiticide 83100-15 0.500% None Lawn Insect Control 2 279-3339 0.200% 0.16% Bifenthrin LPI IMIDACLOPRID 1.0 G 34704-962 1.000% None MALICE® 0.2 Plus Turf Fertilizer 34704-979 0.200% None Mallet®5 G Tree and Shrub Insecticide 228-567 5.000% None Mallet®5 G Turf & Ornamentals Insecticide 228-566 5.000% None Marathon 1% G Insecticide 59807-15 1.000% None Merit® 0.35 Plus Turf Fertilizer 432-1355 0.350% None Merit® 0.45 Plus Turf Fertilizer 432-1356 0.450% None

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EPA Active Ingredient(s) Product Name Reg. No. IMI % Others Merit® 0.2 Granular Insecticide 72155-44 0.200% None Merit® 0.3 G Insecticide 432-1450 0.300% None Merit® 0.22 G Plant Treatment 432-1456 0.220% None Merit® 0.25 Plus Lawn and Garden Fertilizer 72155-36 0.250% None Merit® 1 G Greenhouse and Nursery Insecticide 432-1329 1.000% None Merit® 1.1 %Insecticide 432-1472 1.100% None Merit® FXT Tablet insecticide 432-1457 20.00% None Pro-Mate® Merit® 0.2% With Turf Fertilizer 5905-591 0.200% None QUALI-PRO® IMIDACLOPRID 0.5G INSECTICIDE 66222-200 0.500% None QUALI-PRO® IMIDACLOPRID 1G Nursery & Greenhouse Insecticide 66222-201 1.000% None The Andersons 0.077% Bifenthrin + 0.155% Imidacloprid Granular Insecticide 9198-239 0.155% 0.077% Bifenthrin The Andersons 0.2% Imidacloprid Insecticide + Fertilizer 9198-236 0.200% None TURFTHOR 2.5 G insecticide for turf-grass & landscape ornamentals 83923-9 2.500% None TURFTHOR 0.5 G insecticide for turf-grass & landscape ornamentals 83923-10 0.500% None Pursell PM with Imidacloprid & Fertilizer 8660-252 0.011% None Merit® 0.005% PM Plus Fertilizer 72155-10 0.005% None

Granular formulations are mostly formulated with imidacloprid as a single active ingredient in the range of 0.005 to 5.0% admixed, in some formulations with 0.067 to 0.16% Bifenthrin; 1.06% Tebuconazole; 0.05 to 0.10% Clothianidin; 0.05% β-Cyfluthrin; and 0.10% λ-Cyhalothrin (Table A-14). The only tablet formulation of imidacloprid contains 20% imidacloprid. A summary for the application parameters/procedures for the soil applied granules/tablets formulations are included in Table A-15.

Table A-15 A summary of the application parameters/procedures for the soil applied granular formulations (Data for granular formulation unless it is stated that it is for tablets) Use Pattern Description Application Rate & Procedure Rate: 0.40 lb. a.i/A x One application/year (Y) Grassy areas Grassy areas in Nurseries Procedure: Ground broadcast application Containerized plants not intended to Rate: 0.40 lb. a.i/A x One application/Y Containerized be used as edible food; Potted foliage, Rate for tablets: 0.50 lb. a.i/A x One application/Y ornamentals herbaceous plants & shrubs and listed Procedure: (1) Place and incorporate1 the product into fruit & nut trees the root zone so that the plant can absorb the a.i.; (2) Irrigate moderately, but thoroughly, allowing no leaching Fruiting and Brassica (Cole) and run-off from containers for at least three irrigations Containerized vegetables2 or 10 days whichever is longer vegetables distant for resale for transplant Procedure for Tablets: Place 1-4” deep into the media 2” from outside container edge (Veggies not included) Nurseries Rate: 0.40 lb. a.i/A x One application/Y Rate for tablets: 0.50 lb. a.i/A x One application/Y Procedure: Broadcast in band 6" on both sides of the trees or root ball. Applications must be followed by sufficient mechanical incorporation, irrigation or rainfall Ornamentals in Field nursery/forest nursery to move the a.i into the soil field nursery trees/stock Procedure for Tablets: At planting: Place in the planting hole under roots; Existing trees shrubs: Place at distances/depths depending on tree/shrub type (2-5” below soil surface) or apply around trees/shrubs 2-5” below soil evenly spaced around the tree trunk and along the drip line 155

Use Pattern Description Application Rate & Procedure Rate, including tablets: 0.50 lb. a.i/A x One Landscape application/Y (10% of labels) (Note)3 Ground covers, evergreens, Ornamentals: Procedure: broadcast by spreaders drop and rotary types flowering/foliage plants, foliage Around the followed by mechanical incorporation and watering-in to plants, roses, and small trees & shrubs perimeter of move the active ingredient to root zone industrial and Procedure for Tablets: Same as in nursery commercial Rate, including tablets: 0.50 lb. a.i/A x One buildings and application/Y (10% of labels) (Note)3 residential Other Rates: 0.0094 to 0.0101 lb. a.i/8” to 10” tall areas, and trees Trees, shrubs and non-bearing fruit private Procedure: Spreading in 1-3’ circle from the tree/shrub and nut trees (apple, crabapple, loquat, Residential, wooded/forested trunk depending on the length of the tree/shrub directly mayhaw, oriental pear, pear, pecan, Farm and areas in state, beneath the base of the tree or shrub followed by and quince), Commercia national, and incorporation of the granules by cultivation, irrigation, l private forested rainfall, mechanical placement, or by using mechanical Areas areas soil mixing equipment Procedure for Tablets: Same as in nursery Rodent/Insect Control: Rate: 0.44 lb. a.i/A x One application/Y Fire ant control: Residential, farm & commercial areas Procedure: Assume broadcast treatment Rate: 0.40 lb. a.i/A x One application/Y Perimeter Treatment: To Control Insects Procedure: Band or spot Treatment 3-5 ft. around homes Rate: 0.40 lb. a.i/A x One application/Y Non-structural Termite Control: To establish residues in Procedure: Perimeter 3-10 ft. band and/or soil the top few inches of soil, killing foraging termites that incorporation as spot treatments in advance of final re- may be present at the time of application treatment of the structure Turf Grass Areas: Around Rate: 0.4 to 0.5 lb. a.i/A x One application/Y residential/commercial/industrial/ institutional/ Procedure: Broadcast application. Rainfall (within 24 recreational; parks; athletic fields; business/ Turf hours), irrigation and mechanical incorporation to move office/shopping complexes; airports; cemeteries; and a.i through thatch layer to the soil at the depth of the root playgrounds zone Turf in Sod Farms/Golf courses 1Incorporation of granules can be achieved by cultivation, irrigation, rainfall, mechanical placement or by mechanical mixing of soil or media; 2Fruiting Vegetables include: Eggplant, Ground Cherry, Pepinos, Peppers Tomatillo, and Tomato and Brassica (Cole) vegetables include: Broccoli, Chinese Broccoli, Broccoli Raab, Brussels Sprouts, Cabbage, Chinese Cabbage, Cauliflower, Collards, , Kale; Kohlrabi, Lettuce, Mustard Greens and Rape Greens; Noting that not all of these crops is grown for seedling in the nursery and this is probably the case for Potatoes, Sorghum, Sugarbeet which was also listed, possibly by mistake; 3 Note: Application rates were: One label @ 0.25 lb. a.i/A x two application/Y= 0.50 lb.; One label @ 0.122 lb. a.i/A x two application/year= 0.24 lb.; 64% of examined labels @ 0.40 lb. a.i/A x one application/Y; and 26% of examined labels @ <0.33 lb. a.i/A x one application/Y

(b) Foliar or Soil Applied Liquid Sprays: Some imidacloprid labels are for liquid formulations that are used as foliar or soil sprays. Table A-16 contains a summary for the application parameters/procedures for the foliar or soil applied liquid formulations.

Table A-16 A summary of the application parameters/procedures for the foliar or soil applied liquid formulations1 Use Pattern Description Application Rate & Procedure Rate: 0.40 lb. a.i/A x One application/year (Y) Grassy areas Grassy areas in Nurseries Procedure: Ground broadcast application Containerized plants not intended to Rate: 0.40 lb. a.i/A x One application/Y (Note)2 Nurseries Containerized be used as edible food; Potted foliage, Or : 0.20 lb. a.i/A x 2 application/Y (No intervals ornamentals herbaceous plants & shrubs and listed specified) fruit & nut trees Procedure: (1) Place and incorporate1 the product into

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Use Pattern Description Application Rate & Procedure the root zone so that the plant can absorb the a.i.; (2) Fruiting and Brassica (Cole) Containerized Irrigate moderately, but thoroughly, allowing no leaching vegetables2 vegetables and run-off from containers for at least three irrigations distant for resale for transplant or 10 days whichever is longer Rate: 0.40 lb. a.i/A x One application/Y Procedure: Spray in band 6" on both sides of the trees or Ornamentals in Field nursery/forest nursery root ball. Applications must be followed by sufficient field nursery trees/stock mechanical incorporation, irrigation or rainfall to move the a.i into the soil Ground covers, evergreens, Rate: 0.40 lb. a.i/A x One application/Y (10% of labels) Landscape flowering/foliage plants, foliage Procedure: Foliar spray (ground spray or airblast for Ornamentals: plants, roses, and small trees & shrubs trees) or soil spray with water-in to move the active Around the and Non-bearing fruits/nuts ingredient to root zone; Chemigation perimeter of Rates (Minimum intervals when applicable): industrial and Avocados: 0.094 lb. a.i/A x One application/Y commercial Citrus:0.094 lb. a.i/A x 3 applications/Y (10-d) Bearing Residential Fruit & Nut Trees buildings and Grapes 0.047 lb. a.i/A x 2 application/Y (14-d) Residential, residential areas Pecans & nut trees: 0.094 lb. a.i/A x 3 applications/Y Farm and (10-d) Commercia Rate: One application (cannot calculate from label l information) which calls for preparing 0.05% to 0.1% Areas solution followed by applying 4 gallons of the solution/10 linear ft. of critical areas and 1.5 gallons/10 Structural Termite Control3: For pre-construction/re- sq. ft. for all other areas treatment for structural protection from subterranean Noting that: Critical areas include: inside foundation termites walls, around plumbing, bath traps and utility services; and other areas include: soil to be covered by slab including: basement floor, carports, porches, and entrance platforms Turf Grass Areas: Around Rate: 0.4 to 0.5 lb. a.i/A x One application/Y residential/commercial/industrial/ institutional/ Procedure: Broadcast application. Rainfall (within 24 Turf recreational; parks; athletic fields; business/ hours), irrigation and mechanical incorporation to move office/shopping complexes; airports; cemeteries; and a.i through thatch layer to the soil at the depth of the root playgrounds zone 1 Examined Formulations (All use patterns except those for structural termite control): AmTide 75% WDG Insecticide (Reg. No. 83851 -7; 75% IMI Water dispersible granules ); Merit 60 WSP (Reg. No. 432-1361; 60% IMI Water soluble packets); and Willowood Imidacloprid 4SC (Reg. No. 228-588; 40.7% IMI Soluble concentrate) 2 Note: Label specify the maximum rate/A/Y which would limit the number of pots that can be placed/treated in one acre in a year. 3 Examined Labels for structural termite control included: Liquids: IMI 4 lb Insecticide (53883-237; 42.3% IMI); IMI 2 Ib Insecticide (53883- 229; 21.4%); and Premise 2 Insecticide (432-1331; 21.4% IMI); and Foam: Imidacloprid 0.05% Termite Foam (72155-111) used indoor/outdoor for termites and ants) and PREMISE® FOAM (432-1391; 0.05% Imidacloprid) which is for commercial use by Pest Management Professionals

(2) Poplar/Cottonwood and X-mass Trees Plantations Several liquid formulations are labeled for use on poplar/cottonwood and x-mass trees plantations. Labels for six formulations call for application of the pesticide as foliar spray with two labels calling for either foliar or soil applications. A summary of the application parameters/procedures for the foliar or soil applied liquid formulations is presented in Table A-17.

Table A-17 A summary of the application parameters/procedures for the foliar or soil applied liquid formulations on poplar/cottonwood and x-mass trees plantations1

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Application Parameters2 Use Pattern MS MN MA Application Procedure/Application Window MAI R A R Foliar Spray Application Poplar/cottonwood 0.1 5 0.50 10 Aerial or Ground (Airblast)/Depending on pest and pest pressure. For cottonwood, application prohibited pre-bloom, X-mass trees 0.1 5 0.50 7 during bloom, or when bees are foraging Soil Spray Application (1) Chemigation through low-pressure drip irrigation; and (2) Shank into root-zone followed by adequate irrigation to promote uptake (i.e. 0.25”/A) (For narrow-row, cutting Poplar/cottonwood 0.50 1 0.50 N/A4 orchards/nurseries used for plant propagation) When: Early in the year, from break of dormancy through May. Application prohibited pre-bloom, during bloom, or when bees are foraging, (1) Chemigation into root-zone through low-pressure drip, trickle, micro-sprinkler or equivalent equipment; (2) 18-inch X-mass trees 0.50 1 0.50 N/A band spray on each side of the row (small trees) to full broadcast application (large trees) followed by rainfall or 0.25 to 1” of irrigation within 12 hours after application. 1 Examined Formulations: For Soil & Foliar Application: ADMIRE ™ ® PRO; and GAUCHO® 550 SC; and For Foliar Applications: PROVADO 70 WG; Provado® 1.6 F; PROVADO® PRO; and PROVADO® Solupak 75% 2Application Parameters: MSR= Max Single Rate; MNA= Max Number of Applications; MAR= Max Annual Rate (Rates are in lb. a.i/A); and MAR= Minimum Application Intervals in days; 3N/A= Not applicable

(3) Forestry Several liquid ready to use tree injection products (Table A-18)

Table A-18 A summary of the application parameters/procedures for forestry Use Pattern Formulations; Purpose, When/Where/How to Use, and Application Rates Formulations: SilvaShield™ Insecticide Tablet (432-1484; 20% IMI; each Tablet contains 0.0011 lb. IMI a.i)

Purpose for all formulations: To control insects attacking newly-planted seedlings and established seedling trees in forestry Forest trees: Containerized, When/Where/ How to Us: (1) Seedling in containers prior to planting: place prescribed tablets 1-4” deep into the Newly soil in the container; (2) Bare-root seedlings, rooted and unrooted cuttings, or small trees at planting: place Planted, prescribed tablets 1-3” deep into the soil hole underneath or next to the tree; (3) newly-planted and established trees: and Apply 2-5” below the soil surface within 3-5” of the tree. Established Seedlings Application Rate: Maximum Rate for in-ground plants: 450 tablets= 0.5 lb. IMI a.i/A/Y; One Application; Maximum rate/tree (in-hole at planting or as soon as possible after planting): Poplar/cottonwood= 1 tablet/tree= 0.0011 lb. IMI/tree; Conifer: 2 tablet/tree= 0.0022 lb. IMI/tree. Therefore, a maximum label rate of 450 tablets/A will treat 450 trees of Poplar/cottonwood or 225 trees of Conifer in one acre. Formulations: Merit® Injectable Capsule (432-1463; 17.1% IMI in 3 and 6 mL capsules of liquid formulation with a density of 9.75 lb./gal “BEAD report”= 0.000440489 lb. IMI a.i/mL; 3 mL capsule contains 0.0013215 lb. Trees, IMI and 6 mL capsule contains 0.0026429 lb. IMI) Including

Forest Trees, Purpose: For injection into trees in nurseries, greenhouses, and interior and exterior landscaped area, and in private, And municipal, state, and national forested areas to control a variety of insect pests of ornamental or forest trees. Not Shrubs for use on trees where the fruits and/or nuts are consumed

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Use Pattern Formulations; Purpose, When/Where/How to Use, and Application Rates Where/When to Use: Post bloom (For bee-pollinated dicotyledonous trees) tree trunk injection of shrubs and trees >2” in trunk diameter

Application Procedure: Applied using the Tree Tech microinjection system. Microinjection units should be installed in a hole drilled in the stem and root flares every 6” around the trunk 6-8” from the soil surface

Application Rate: Maximum rate= One capsule (0.0026429 lb. IMI a.i/2” of trunk diameter @ chest height (other labels refers to it as the tree diameter at breast height or DBH); For example, if the trunk diameter@ chest height = 12”, then the rate= 6 capsules (12 divided by 2). The rate would be 6 x 0.0013215 lb. IMI a.i= 0.0079288 lb. IMI a.i/12” tree when a 3 mL capsule is used Or 6 x 0.0026429 lb. IMI a.i= 0.0158576 lb. IMI a.i/12” tree when a 6 mL capsule is used (Label not clear which can be used) Formulations: (1) IMICIDE® HP (7946-25; 10% IMI of liquid containing 110.7 mg of IMI/mL= 0.00024405 lb. IMI a.i/mL; and (2) The same product under the name: Mauget® IMICIDE® (7946-16) in ready to use capsules containing 2, 3, 4, 8, 12, 16 mL ready to use capsules

Purpose: Same as Merit® Injectable Capsule, above

Where/When to Use: Same as Merit® Injectable Capsule, above

Application Procedure: For product (1): Use of liquid loadable, pressure tree injector system. 1st determine the tree diameter at breast height (DBH); 2nd determine the No. of injection sites= DBH divided by 2; 3rd determine total and dosage/tree and dosage per injection site based on DBH in inches: 1st category: DBH >2-10”; 2nd category: DBH 10-36”; and 3rd category: DBH >36. Total dosage for 1st category tree in mL of product= DBH x 1; for 2nd

category tree= DBH x 1.5; and for 3nd category tree= DBH x 2. The maximum for all categories is DBH x 2 (heavy infestation/resistant insects). Following determination of the total dosage/tree and the number of injection sites, the dose e site is determined by dividing total dosage/tree by the No. of injection sites. A special rate of 2 mL x DBH (2-23” DBH) and 4 mL x DBH (>24” DBH) are specified, in the label, for USDA supervised treatment program of Asian and Citrus Long-horned beetle. For product (2): determine the total dose, number of sites and the dose for each site the same way as in product (1) then choose the required capsules/capacity needed for the treatment. In each site a hole is drilled into the conductive xylem tissue, the micro injector and feeder tube is combined, feeder tube is placed into the tree and the product is injected into the tree.

Application Rate: Example, A tree with 12” DBH; No of sites= 6 (12 divided by 2); Total dosage= 24 mL of product (12 x 2 mL) Or 24 x 0.00024405 lb. IMI a.i= 0.0058571 lb. IMI a.i/12” tree applied @ 6 sites with 4 mL dose in each site (24 mL divided by 6) Formulations: POINTER® Insecticide S (69117-8; 5% IMI of liquid; 0.025 Oz./15 mL= 0.001667 Oz./one mL= 0.00010417 lb. IMI a.i/One mL

Purpose: Same as Merit® Injectable Capsule, above

Where/When to Use: Same as Merit® Injectable Capsule, above

Application Procedure: Applied by syringe that delivers one mL of product into sites (holes) drilled around the base of the tree 12” of the ground. Total dose in mL/tree is determined by the number of sites (holes) which is specified in the label depending on the measured circumference of the tree as follows: 4” (1 site x 1= 1 mL), 12” (3 sites x 1= 3 mL), 24” (6 sites x 1= 6 mL), 36” (9 sites x 1= 9 mL), 48” (12 sites x 1= 12 mL), 60” (15 sites x 1= 15 mL), Application Rate: Example, A tree with 12” Diameter will have a 37.7” circumference. As per label the rate will be 1 mL x 9 sites= 9 mL (36” is the nearest to 37.7”); Total dosage= 9 mL of product x 0.00010417 lb. IMI a.i = 0.0009375 lb. IMI a.i/12” tree applied @ 9 sites with 1 mL dose in each site

(4) Bait & Pellets in farms/residential/commercial areas

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Imidacloprid is formulated alone or with other active ingredients as baits, pellets and blocks for use patterns summarized in Table A-19, A-20 and A-21).

Table A-19 Summary of the application parameters/procedures for bait & pellets (Rodents & Flies) Use Formulation; Purpose and Where Can Be Used Application Rate & Procedure Pattern Formulations: (1) Kaput DOOM Smacker Bait (72500-19; 0.02% IMI + 0.005% Bromadiolone); (2) Novel Commensal Rodent Pellet #2: (72500-13; 0.020% IMI + 0.025% Warfarin); (3) Kapuf®-D Combo Bait Blocks (72500-18; 0.020% IMI + 0.005% Diphacinone); (4) Kaput® Combo Bait® Mini Blocks (72500-14; 0.02% IMI + 0.02% Warfarin); and (5) KAPUT® RODENT FLEA CONTROL BAIT (72500-17; 0.025% IMI)

Purpose for all formulations: To kill Norway Rats, Roof Rats and House Mice & their infesting fleas (IMI + Rodenticide) Or just rodents’ fleas alone (IMI alone)

Where/When to Use for all formulations: Indoors or within 50 ft. around homes and other residential buildings, Rodents industrial/agricultural buildings and similar man-made structures; ships, trains and aircrafts Plus Infesting Application Procedure: Flees (1) Kaput DOOM Smacker Bait: Placed in bait stations with the use of tamper-resistant bait stations indoors. Bait is Control placed in these stations and fresh bait is added for 10-days or as required. Maximum of 2 blocks for house mice Or 16 blocks for Norway/roof rats (block= one Oz)/station with stations placed 8 Or 15 ft. apart, respectively; (2) Novel Commensal Rodent Pellet #2: Placed in bait; (3) Kapuf®-D Combo Bait Blocks: Placed in bait; (4) Kaput® Combo Bait® Mini Blocks: Placed in bait; (5) KAPUT® RODENT FLEA CONTROL BAIT: Placed in bait

Application Rate: (1) Kaput DOOM Smacker Bait: (a) Norway/Roof Rats: Maximum 16 Oz bait= 1 lb. bait Contains 1 lb. bait x 0.0002 lb. IMI= 0.000200 lb. IMI a.i/Bait station (b) House Mice: Maximum 2 Oz bait= 0.125 lb. bait Contains 0.125 lb. bait x 0.0002 lb. IMI= 0.000025 lb. IMI a.i/Bait station Formulations: (1) QuickBaytTM Disposable Fly Bait Strip (11556-140; 0.5% IMI + 0.1% Z-9-tricosene; (2) Window Fly Killer (Inside window sticker; 43419-2; 4.3% IMI + 0.21% Z-9 tricosene; (3) PRE-EMPT® FLY BAIT (432-1375; Granular 0.50% IMI + 0.10% Z-9-Tricosene; and (4) QuickBayt® Fly Bait (11556-137; 0.5% IMI + 0.10% Z-9-Tricosene

Purpose/Where/When to Use: Product (1): for flies control inside homes Product 2: for fly control in/around commercial livestock facilities (dairy, meat, and poultry processing plants), in/around agricultural production facilities (poultry houses, feedlots and dairies), in/around stables/kennels, and around commercial facilities. Flies Product (3): for fly control outside structures, in/around agricultural production facilities and around commercial Control facilities Product (4): For the control of nuisance flies scattered in/around livestock facilities, stables, walkways of caged layer houses; and in bait stations inside Swine confinement buildings, and Dairy barns and milking parlors Apply at the start of the season before fly populations have reached their peak

Application Procedure: Product 1: Place Bait strips on areas where the flies present; Product 2: Place strips on inside windows; and Products 3 & 4: Applied scatter, in bait stations and as paint-on

Application Rate (1) QuickBaytTM Disposable Fly Bait Strip: One strip “ a.i per strip not specified)/250 sq. ft. in 8 weeks when needed; (2) Window Fly Killer: One bait strip (0.00000008265 lb. IMI a.i)/Window. every 6 months; (3) PRE-EMPT® FLY BAIT: Scatter rate: 0.00196875 lb. IMI a.i/1,000 sq. ft. repeat as needed every 7 days; and

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Use Formulation; Purpose and Where Can Be Used Application Rate & Procedure Pattern (4) QuickBayt® Fly Bait: Scatter rate: 0.001875 lb. IMI a.i/1,000 sq. ft. Label did not specify repeated applications (As per registrant the 52 applications/year). Maximum rate= 0.0858 lb. a.i/A/year (registrant value= 0.023?)

Table A-20 Summary of the application parameters/procedures for bait & pellets (CA ground squirrels and Cat & dog neck collar) Use Pattern Formulation; Purpose and Where Can Be Used Application Rate & Procedure Formulation: Kaput Field Rodent Bait B (72500-11; 0.025% IMI + 0.0025% Diphacinone)

Purpose: To kill California ground squirrels and reduce fleas that infest the squirrel

Where/When to Use: In parks, golf courses, fruit tree orchards (dormant season only), non-crop rights-of-way and other non-crop areas. Apply when squirrels are readily accepting grains

Application Procedure: Manually scatter 0.15625 lb. of bait on ground or in modified bait stations (inverted "T" with "elbows" or platform station) near each active burrow. Area treated around burrow may not be >50 sq. ft. Maximum number of applications= 4 with a minimum interval of 2 days

Application Rate (lb. IMI a.i/Burrow): CA Maximum 0.15625 lb. of Bait x 4 applications= 0.0000390625 lb. IMI a.i x 4= Ground 0.00015625 lb. IMI a.i/ Burrow @ 2-day intervals Squirrels Formulation: Kaput Ground Squirrel Bait (72500-24; 0.0250% IMI + 0.0025% Diphacinone) Control Purpose: To kill California ground squirrels and reduce fleas that infest the squirrel

Where/When to Use: Around buildings including areas such as yards and flower gardens. Assume that it will be applied when squirrels are readily accepting grains

Application Procedure: Apply at locations where the bait will be readily accessible to CA ground squirrels (near active burrows) in secured, tamper-resistant bait stations at a minimum of 20 ft. apart. Use a maximum of 4 lbs. per bait station. Insure that an uninterrupted supply of bait is always available for at least 15 days, or until there no longer are any signs of feeding.

Application Rate: 4 lbs. bait x 0.025%= 0.0010 lb. IMI a.i/ Bait Station (Note: rate without consideration of the required replenishment of bait during the 15 days period) Formulations: PNR1427 Insecticide (11556-155; Slow release water resistant neck collar; 10% IMI + 4.5% Flumethrin) Cats

And Purpose: 8-month prevention and treatment of ticks, fleas, and lice on cats and dogs Dogs

Neck Where/When to Use: Neck collar when needed Collar

Application Rate: Cannot be calculated

Table A-21 Summary of the application parameters/procedures for bait & pellets (Household insects) Use Formulation; Purpose and Where Can Be Used Application Rate & Procedure Pattern Household Insects Formulations: Imidacloprid Ant Killer Station (72155-67; liquid pre-filled spill resistant bait station; 0.005% IMI) Control:

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Use Formulation; Purpose and Where Can Be Used Application Rate & Procedure Pattern Ants Purpose: To kill wide variety/common household ants

Where/When to Use: Indoors/outdoors when/where ants are present. Indoors: Attics, basements, bathrooms, closets, dining rooms kitchens, pantries and storage areas. Outdoors: Directly over ant nests/trails or where ants have been seen entering the building.

Application Procedure: Place bait station upright by ant trails or near areas where ants have been Seen (did not specify how many stations/sq. ft.)

Application Rate: Cannot be calculated Formulations: Imidacloprid Granular Bait (73079-14; 0.5% IMI)

Purpose: To kill ants (excluding carpenter, fire, pharaoh and harvester), roaches, crickets, mole crickets, silverfish, firebrats, and earwigs

Where/When to Use: Indoors/outdoors structures, including homes, apartments, commercial, industrial, municipal, institutional, research, recreational, health care, educational, daycare, hospitality and agricultural buildings and other man-made structures, garages, transport vehicles, sewers, animal research facilities, and food service, storage, handling Household and processing establishments. Turf sites include lawns, landscape beds, ornamental turf, parks, playing fields, right-of- Insects ways, golf course greens and tee boxes, homes, and greenhouses Control: Others Application Procedure: Outdoors: Use a hand-shaker, duster or mechanical spreader to apply in a band 1-3 ft around the perimeter of the building, edges of sidewalks, patios and driveways and under decks mulch beds, flowerbeds, fruit and vegetable gardens, compost heaps, wood piles, trees, stumps and trash areas and For ants, around trees and stumps, in tree cavities, in and around firewood piles, around landscaping stones and in mulch beds, Turf areas, and along ledges inside sewers and around manhole covers. Indoor Application: Apply in tamper-resistant bait stations in the presence of children or by hand shaker or duster in crack, crevice or void and around many places where the insects may hide.

Application Rate: Perimeter Outdoors/Sewer: 0.003125 lb. IMI a.i/1,000 sq. ft., Turf: 0.00255 lb. IMI a.i/1,000 sq. ft., Indoors: 0.00156 lb. IMI a.i/1,000 sq. ft., Re-apply in 7 days (Maximum No. of applications not stated)

Appendix B. Example PWC Model Runs

Appendix II

This Appendix II contains examples of selected modeling runs in the form of a screen shoot of important windows from the actual model runs. These examples contain modeling inputs used in these runs as well as resultant outputs. Inputs presented, hereunder, may be used to generate similar runs for verification, if needed.

All Runs: Inputs: Chemical Parameters

162

Example 1: 1st Brassica Run: Inputs: Application Parameters

163

1st Brassica Run: Outputs

Example 1: 2nd Brassica Run: Inputs: Application Parameters

164

2nd Brassica Run: Outputs

Example 1: 3rd Brassica Run: Inputs: Application Parameters 165

3rd Brassica Run: Outputs

Example 2: 1st Bulb Vegetables Run: Inputs: Application Parameters

166

1st Bulb Vegetables Run: Outputs

Example 2: 2nd Bulb Vegetables Run: Inputs: Application Parameters

167

2nd Bulb Vegetables Run: Outputs

Example 2: 3rdBulb Vegetables Run: Inputs: Application Parameters 168

3rd Bulb Vegetables Run: Outputs

Example 2: 4th Bulb Vegetables Run: Inputs: Application Parameters

169

4th Bulb Vegetables Run: Outputs

Example 3: 1st Citrus Run: Inputs: Application Parameters

170

Batch Run representative scenarios for 250-day window in 5-day steps

1st Citrus Batch Run: Outputs

171

EECs were obtained for the three scenarios for an application window of 250 days in steps in 5-day steps (Generate 50 runs for each scenario). Results obtained for CA-Citrus and STX-grapefruits were lower than those obtained for FL-citrus after omitting EECs for the restricted application timing of 15-Mar to 30-Apr. Hereunder an example of how the EECs were selected for FL-citrus by omitting restricted application dates from1-Jan to 28-Feb (as indicated below by shading with text strikethrough).

ECO EECs (ppb) Scenario_ Equivalent Surface Water Pore Water +days from 30-Jan Date Peak 21-day 60-day Peak 21-day FLcitrusSTD_+0 30-Jan 8.13 5.53 3.46 2.03 1.99 FLcitrusSTD_+5 4-Feb 8.66 6.53 4.13 2.34 2.29 FLcitrusSTD_+10 9-Feb 10.3 7.83 4.4 2.4 2.36 FLcitrusSTD_+15 14-Feb 8.48 5.72 4.13 2.25 2.2 FLcitrusSTD_+20 19-Feb 8.82 6.17 4.46 2.41 2.36 FLcitrusSTD_+25 24-Feb 9.85 6.82 5.01 2.73 2.67 FLcitrusSTD_+30 29-Feb 10.2 7.01 4.84 2.71 2.66 FLcitrusSTD_+35 5-Mar 11.3 7.36 4.91 2.78 2.72 FLcitrusSTD_+40 10-Mar 12 7.88 4.41 2.54 2.49 FLcitrusSTD_+45 15-Mar 9.81 6.88 4.24 2.33 2.28 FLcitrusSTD_+50 20-Mar 9.68 6.33 4.27 2.35 2.3 FLcitrusSTD_+55 25-Mar 10.5 7.2 4.39 2.42 2.37 FLcitrusSTD_+60 30-Mar 10.9 7.31 4.18 2.31 2.27 FLcitrusSTD_+65 4-Apr 11.6 7.7 4.43 2.43 2.38 FLcitrusSTD_+70 9-Apr 11.9 7.87 4.89 2.66 2.61 FLcitrusSTD_+75 14-Apr 11.4 7.48 4.37 2.33 2.29 FLcitrusSTD_+80 19-Apr 10.6 7.09 4.14 2.29 2.24 FLcitrusSTD_+85 24-Apr 10.1 7.13 4.82 2.62 2.57 FLcitrusSTD_+90 29-Apr 9.16 5.86 3.47 1.88 1.84 FLcitrusSTD_+95 4-May 8.21 5.51 3.32 1.86 1.83 FLcitrusSTD_+100 9-May 9.78 6.43 3.66 2.03 2 FLcitrusSTD_+105 14-May 12.8 8.38 4.62 2.62 2.57 FLcitrusSTD_+110 19-May 8.52 5.52 3.67 1.94 1.91 FLcitrusSTD_+115 24-May 9.27 6.42 3.58 1.93 1.89 FLcitrusSTD_+120 29-May 8.23 5.75 3.7 2.05 2.01 FLcitrusSTD_+125 3-Jun 9.14 6.02 3.97 2.18 2.13 FLcitrusSTD_+130 8-Jun 9.2 6.62 3.79 2.03 1.98 FLcitrusSTD_+135 13-Jun 7.32 5.29 3.21 1.77 1.73 FLcitrusSTD_+140 18-Jun 8.58 6.37 3.82 2.01 1.97 FLcitrusSTD_+145 23-Jun 7.27 5.45 3.35 1.72 1.7 FLcitrusSTD_+150 28-Jun 8.39 5.55 3.73 1.88 1.85 FLcitrusSTD_+155 3-Jul 6.9 4.84 2.7 1.48 1.45 FLcitrusSTD_+160 8-Jul 7.96 5.18 3 1.61 1.58

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FLcitrusSTD_+165 13-Jul 9.05 5.68 3.27 1.81 1.77 FLcitrusSTD_+170 18-Jul 9.69 6.08 3.53 1.95 1.91 FLcitrusSTD_+175 23-Jul 7.85 5.46 3.58 1.87 1.84 FLcitrusSTD_+180 28-Jul 9.09 6.31 3.75 1.95 1.91 FLcitrusSTD_+185 2-Aug 9.28 6.06 3.81 2.02 1.98 FLcitrusSTD_+190 7-Aug 9.43 6.29 4.02 2.14 2.09 FLcitrusSTD_+195 12-Aug 9.16 6.08 3.67 2.02 1.97 FLcitrusSTD_+200 17-Aug 9.95 6.62 3.99 2.16 2.11 FLcitrusSTD_+205 22-Aug 9.57 6.63 4.29 2.24 2.19 FLcitrusSTD_+210 27-Aug 10.6 7.14 4.12 2.24 2.2 FLcitrusSTD_+215 1-Sep 11.6 8.01 4.48 2.45 2.4 FLcitrusSTD_+220 6-Sep 12.4 8.3 4.68 2.6 2.55 FLcitrusSTD_+225 11-Sep 12 7.73 4.59 2.51 2.46 FLcitrusSTD_+230 16-Sep 12.9 8.94 5.15 2.9 2.84 FLcitrusSTD_+235 21-Sep 13.8 8.61 4.66 2.56 2.9 FLcitrusSTD_+240 26-Sep 15.6 9.88 5.61 3.04 3.49 FLcitrusSTD_+245 1-Oct 14.2 9.9 5.82 3.27 3.21 FLcitrusSTD_+250 6-Oct 13.1 10.2 5.96 3.21 3.16 Min 6.90 4.84 2.70 1.48 1.45 Max 15.60 10.20 5.96 3.27 3.49 Average 10.08 6.84 4.16 2.27 2.24 SD 1.87 1.24 0.68 0.39 0.42 Average Deviation 1.49 0.99 0.54 0.31 0.33 Median 9.69 6.62 4.13 2.25 2.20

As shown in the table above, the highest EECs for FL-citrus use pattern were generated from a first application of 26-sep. These EECs were taken to represent citrus use in Florida. A single run for FL-Citrus with two applications are shown below:

Single run for the Selected date

173

Example 3: 2nd Citrus Run Inputs: Application Parameters

Same run as above with different inputs for soil application by chemigation (uniform below with 60 cm depth of the root zone as shown below:

174

Example 3: 3rd Citrus Run Inputs: Application Parameters

A run with different inputs representing Transplants with soil drench (transplanting depth= 30 cm)

Example 3: 4th Citrus Run Inputs: Application Parameters

A run with different inputs representing Transplants with Foliar spray

175

Appendix C. Relevant Ecotoxicity Data (Apical Endpoints) from EPA’s ECOTOX Database

176

Table C-1. Invertebrates Tested with Imidacloprid (Source: ECOTOX, Apical Endpoints, Duration 1-4 d)

Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect

Phylum: Annelida

Clitellata Lumbriculida Lumbriculidae Lumbriculus variegatus Oligochaete, IMLB EC05 FW 0.0062 102580 Worm Phylum: Arthropoda

Branchiopoda Cladocera Moinidae Moina macrocopa Water Flea IMBL EC50 FW 45.271 34.378 62.218 157952

Branchiopoda Diplostraca Chydoridae Chydorus sphaericus Water Flea IMBL EC50 FW 2.209 1.289 3.787 89717 Branchiopoda Diplostraca Chydoridae Chydorus sphaericus Water Flea IMBL EC50 FW 0.832 0.274 2.522 89717

Branchiopoda Diplostraca Chydoridae Chydorus sphaericus Water Flea MORT LC50 FW 132.673 68.426 257.24 89717

Branchiopoda Diplostraca Chydoridae Chydorus sphaericus Water Flea IMBL EC50 FW 18.683 10.891 32.05 89717

Branchiopoda Diplostraca Chydoridae Chydorus sphaericus Water Flea MORT LC50 FW 161.95 61.05 429.614 89717

Branchiopoda Diplostraca Chydoridae Chydorus sphaericus Water Flea IMBL EC50 FW 1.469 0.25 8.619 89717

Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea MORT LC50 FW 0.00207 0.00114 0.0034 151757

Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea IMBL EC50 FW 0.57162 0.2896 0.8412 157952

Branchiopoda Diplostraca Daphniidae Ceriodaphnia reticulata Water Flea IMBL EC50 FW 5.5529 4.2133 7.3878 157952

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 6.029 0.332 109.433 89717

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT LC50 FW 10.44 6.97 17.71 18476

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 11.822 0.464 301.256 89717

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Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT LC50 FW 17.36 12.51 30.05 18476

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 30 28 44 150163 (AI Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 43.265 34.30 mg/L53.59) 157952

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 56.6 34.4 77.2 150163

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT LC50 FW 64.873 7.871 534.68 89717

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 90.68 82.04 99.3 162193

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea IMBL EC50 FW 96.65 87.83 105.6 162193

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT LC50 FW 97 159937

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT LC50 FW 320 89717

Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT LC50 FW 10 20 101983 (% v/v) Branchiopoda Diplostraca Daphniidae Daphnia pulex Water Flea IMBL EC50 FW 36.87 28.40 48.106 157952

Insecta Diptera Chaoboridae Chaoborus obscuripes Midge IMBL EC50 FW 0.284 166772

Insecta Diptera Chaoboridae Chaoborus obscuripes Midge MORT LC50 FW 0.294 0.247 0.35 166772

Insecta Diptera Chironomidae Chironomus dilutus Midge MORT LC50 FW 0.00265 0.0016 0.00358 160293

Insecta Diptera Chironomidae Chironomus riparius Midge MORT LC50 FW 0.0199 0.01464 0.02716 165043

Insecta Diptera Chironomidae Chironomus tentans Midge MORT LC50 FW 0.00265 0.0016 0.00358 167874

Insecta Diptera Chironomidae Chironomus tentans Midge MORT LC50 FW 0.0054 0.00401 0.00728 110523

Insecta Diptera Chironomidae Chironomus tentans Midge MORT LC50 FW 0.00575 0.0041 0.00808 110523

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Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Yellow Fever Insecta Diptera Culicidae Aedes aegypti MORT LC50 FW 0.139 0.069 0.246 168249 Mosquito

Yellow Fever Insecta Diptera Culicidae Aedes aegypti MORT LC50 FW 0.0818 0.0477 0.13636 101958 Mosquito

Yellow Fever Insecta Diptera Culicidae Aedes aegypti MORT LC50 FW 0.36 0.28 0.962 168249 Mosquito

Yellow Fever Insecta Diptera Culicidae Aedes aegypti MORT LC50 FW 0.044 0.041 0.047 18476 Mosquito

Yellow Fever Insecta Diptera Culicidae Aedes aegypti MORT LC50 FW 0.045 0.042 0.048 18476 Mosquito

Asian Tiger Insecta Diptera Culicidae Aedes albopictus MORT LC50 FW 0.2931* 0.1954 0.4885 99823 Mosquito

Asian Tiger Insecta Diptera Culicidae Aedes albopictus MORT LC50 FW 0.5862* 0.3908 0.7816 99823 Mosquito

Asian Tiger Insecta Diptera Culicidae Aedes albopictus MORT LC50 FW 0.7816* 0.5862 0.977 99823 Mosquito

Asian Tiger Insecta Diptera Culicidae Aedes albopictus MORT LC50 FW 0.5862* 0.3908 0.8793 99823 Mosquito

Asian Tiger Insecta Diptera Culicidae Aedes albopictus MORT LC50 FW 0.4885* 0.3908 0.6839 99823 Mosquito Southern Quinquefasciatus Insecta Diptera Culicidae Culex House MORT LC50 FW 0.00076* 99823

Mosquito

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Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00082* 168590 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00096* 168590 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00104* 168590 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00118* 168590 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00177* 168590 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00672* 168590 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.00784* 168590 Mosquito Southern 0.013 Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.0105* 0.008 168590 (ml/L) Mosquito Southern 0.014 Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.011 0.0085 168590 (ml/L) Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.0390* 0.02931 0.04885 88223 Mosquito Southern Insecta Diptera Culicid00ae Culex quinquefasciatus House MORT LC50 FW 0.1954* 0.0977 0.3908 88223 Mosquito

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Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.2931* 0.0977 0.5862 88223 Mosquito Southern Insecta Diptera Culicidae Culex quinquefasciatus House MORT LC50 FW 0.3908* 0.1954 0.5862 88223 Mosquito Insecta Diptera Simuliidae Simulium latigonium Black Fly MORT LC50 FW 0.00373* 0.00154 0.00905 109202

Insecta Diptera Simuliidae Simulium vittatum Blackfly MORT LC50 FW 0.00675 0.00604 0.00741 81392

Insecta Diptera Simuliidae Simulium vittatum Blackfly MORT LC50 FW 0.00825 0.00756 0.00887 81392

Insecta Diptera Simuliidae Simulium vittatum Blackfly MORT LC50 FW 0.00954 0.00871 0.01057 81392

Insecta Ephemeroptera Baetidae Baetis rhodani Mayfly MORT LC50 FW 0.00849* 0.00445 0.0162 109202

Insecta Ephemeroptera Baetidae Cloeon dipterum Mayfly IMBL EC50 FW 0.00102 0.00046 0.00228 166772

Insecta Ephemeroptera Baetidae Cloeon dipterum Mayfly MORT LC50 FW 0.0263 0.0177 0.0391 166772

Insecta Ephemeroptera Caenidae Caenis horaria Mayfly IMBL EC50 FW 0.00177 0.00105 0.00299 166772

Insecta Ephemeroptera Caenidae Caenis horaria Mayfly MORT LC50 FW 0.00668 0.00419 0.0106 166772

Insecta Ephemeroptera Heptageniidae Epeorus longimanus Mayfly MORT LC50 FW 0.00065 102580

Insecta Ephemeroptera Heptageniidae Epeorus longimanus Mayfly MORT LC50 FW 0.0021 102580

Insecta Ephemeroptera Heptageniidae Epeorus longimanus Mayfly MORT LC50 FW 0.0021 102580

Insecta Ephemeroptera Heptageniidae NR Heptageniidae Mayfly Family MORT LC50 FW 0.0037 0.0028 0.0048 167874

Insecta Heteroptera Corixidae Micronecta sp. Lesser Water IMBL EC50 FW 0.0108* 0.00972 0.012 166772 Boatmen Insecta Heteroptera Corixidae Micronecta sp. Lesser Water MORT LC50 FW 0.0282 0.0176 0.0452 166772 Boatmen

181

Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Insecta Heteroptera Notonectidae Notonecta sp. Backswimmer IMBL EC50 FW 0.0182 0.00924 0.0357 166772

Insecta Heteroptera Notonectidae Notonecta sp. Backswimmer MORT LC50 FW 10 0 10 166772

Insecta Heteroptera Pleidae Plea minutissima Water Bug IMBL EC50 FW 0.0359 0.0311 0.0415 166772

Insecta Heteroptera Pleidae Plea minutissima Water Bug MORT LC50 FW 0.0375 166772

Insecta Megaloptera Sialidae Sialis lutaria Alderfly IMBL EC50 FW 0.0506 0.0309 0.0828 166772

Insecta Megaloptera Sialidae Sialis lutaria Alderfly MORT LC50 FW 10 0 10 166772

Insecta Trichoptera Hydropsychidae Cheuma brevilineata Caddisfly IMBL EC50 FW 0.00422 0.00381 0.00451 152279 topsyche Insecta Trichoptera Hydropsychidae Cheuma brevilineata Caddisfly IMBL EC50 FW 0.00485 0.00458 0.00506 152279 topsyche Insecta Trichoptera Hydropsychidae Cheuma brevilineata Caddisfly IMBL EC50 FW 0.00524 0.00498 0.0055 152279 topsyche Insecta Trichoptera Limnephilidae NR Limnephilidae Caddisfly IMBL EC50 FW 0.00179 0.00099 0.00322 166772 Family 3 Insecta Trichoptera Limnephilidae NR Limnephilidae Caddisfly MORT LC50 FW 0.0257 0.0181 0.0365 166772 Family Malacostraca Amphipoda Gammaridae Gammarus fossarum Scud MORT LC50 FW 0.07* 152830

Malacostraca Amphipoda Gammaridae Gammarus fossarum Scud MORT LC50 FW 0.8* 150031

Malacostraca Amphipoda Gammaridae Gammarus pulex Scud IMBL EC50 FW 0.0183 0.00884 0.0378 166772

Malacostraca Amphipoda Gammaridae Gammarus pulex Scud MORT LC50 FW 0.263 0.155 0.446 166772

Malacostraca Amphipoda Gammaridae Gammarus pulex Scud MORT LC50 FW 0.27 0.17 0.45 109202

Malacostraca Amphipoda Gammaridae Gammarus pulex Scud IMBL LC50 FW 514 298 888 153561 (nmol/L Malacostraca Amphipoda Gammaridae Gammarus pulex Scud IMBL LC50 FW 405 225 729) 153561 (nmol/L Malacostraca Amphipoda Gammaridae Gammarus pulex Scud MORT LC50 FW 3.66415 ) 153560

182

Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Malacostraca Amphipoda Gammaridae Gammarus pulex Scud IMBL LC50 FW 430 279 664 153561 (nmol/L Malacostraca Amphipoda Gammaridae Gammarus roeseli Scud IMBL EC50 FW 0.0019* 0.0001 0.0336) 160124

Malacostraca Amphipoda Gammaridae Gammarus roeseli Scud IMBL EC50 FW 0.0142 0.0064 0.0312 160124

Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MORT LC50 FW 0.01744 0.01333 0.02281 110523

Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MULT EC50 FW 0.0333 0.0231 0.0471 168956

Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MORT LC50 FW 0.06543 0.03978 0.10762 110523 Aquatic Malacostraca Isopoda Asellidae Asellus aquaticus IMBL EC50 FW 0.119 166772 Sowbug Aquatic Malacostraca Isopoda Asellidae Asellus aquaticus MORT LC50 FW 0.316 0.216 0.461 166772 Sowbug Aquatic Malacostraca Isopoda Asellidae Asellus aquaticus MORT LC50 FW 8.5 150031 Sowbug Aquatic Malacostraca Isopoda Asellidae Asellus aquaticus MORT LC50 FW 8.5 152830 Sowbug Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua IMBL EC50 FW 0.003 0.0005 0.015 89717 Seed Shrimp Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua MORT LC50 FW 0.715 0.365 1.4 89717 Seed Shrimp Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua MORT LC50 FW 0.273 0.054 1.379 89717 Seed Shrimp Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua IMBL EC50 FW 0.01 0.0013 0.073 89717 Seed Shrimp Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua MORT LC50 FW 4 89717 Seed Shrimp Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua IMBL EC50 FW 0.018 0.0013 0.047 89717 Seed Shrimp Ostracod, Ostracoda Podocopa Cypridopsidae Cypridopsis vidua IMBL EC50 FW 0.016 0.0013 0.21 89717 Seed Shrimp

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Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Ostracoda Podocopida Cyprididae Cypretta seurati Ostracod IMBL EC50 FW 0.016 0.007 0.039 89717

Ostracoda Podocopida Cyprididae Cypretta seurati Ostracod IMBL EC50 FW 0.001 0.0004 0.002 89717

Ostracoda Podocopida Cyprididae Cypretta seurati Ostracod MORT LC50 FW 0.301 0.187 0.485 89717

Ostracoda Podocopida Cyprididae Cypretta seurati Ostracod IMBL EC50 FW 0.046 0.013 0.161 89717

Ostracoda Podocopida Cyprididae Cypretta seurati Ostracod MORT LC50 FW 0.732 0.456 1.176 89717

Ostracoda Podocopida Cyprididae Cypretta seurati Ostracod IMBL EC50 FW 0.012 0.005 0.029 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod MORT LC50 FW 0.214 0.098 0.463 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod MORT LC50 FW 0.517 0.27 0.989 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod IMBL EC50 FW 0.003 0.001 0.011 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod IMBL EC50 FW 0.003 0.0002 0.048 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod MORT LC50 FW 0.759 0.337 1.709 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod MORT LC50 FW 1.122 0.518 2.432 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod IMBL EC50 FW 0.013 0.004 0.048 89717

Ostracoda Podocopida Ilyocyprididae Ilyocypris dentifera Ostracod IMBL EC50 FW 0.005 0.001 0.025 89717

Phylum: Nemata

Parasitic Adenophorea Mermithida Mermithidae Agamermis unka MORT LC50 FW 1.58 1.26 1.98 63774 Nematode * Test results considered invalid for quantitative or qualitative use in risk assessment; Values in bold represent lowest values considered for quantitative or qualitative use in risk assessment. In cases, values used in risk assessment were re-calculated per EFED standard statistical methods and may differ from values in this table.

184

Table C-2. Relevant Chronic Toxicity Data for Freshwater Invertebrates Tested with Imidacloprid (Source: ECOTOX, Apical Endpoints, Dur. > 4d)

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea FCND NOAEL FW 0.000305 151757 Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea PGRT LOAEL FW 0.000305 151757 Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea ABND LOAEL FW 0.000305 151757 Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea ABND LOAEL FW 0.000305 151757 Branchiopoda Diplostraca Daphniidae Ceriodaphnia dubia Water Flea PGRT LOAEL FW 0.000305 151757 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 0.1485 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MATR NOAEL FW 0.1485 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH LOAEL FW 0.1485 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 0.178 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 0.178 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 0.178 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND LOAEL FW 0.178 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 0.178 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 0.178 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 1.188 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 1.25 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 1.287 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2 168382

185

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2 166654 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2.475 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea TFPG NOAEL FW 2.475 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2.475 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea TFPG NOAEL FW 2.5 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 2.5 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MATR NOAEL FW 3.96 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 4 166654 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 4.95 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT NOAEL FW 4.95 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 5 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 11.88 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea PROG NOAEL FW 11.88 169031 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea LGTH NOAEL FW 12.23 168958

186

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea ABND NOAEL FW 12.23 168958 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT NOAEL FW 20 100844 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 29.62 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 29.63 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 42.46 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 42.85 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 43.28 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 43.4 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 47.16 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 47.16 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 54.16 168382

187

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 55.96 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 59.85 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 60.06 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 60.1 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 67.66 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 68.65 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 79.69 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 80.83 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 95.11 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 141.92 168382 Branchiopoda Diplostraca Daphniidae Daphnia magna Water Flea MORT EC10 FW 144.64 168382 Insecta Diptera Chaoboridae Chaoborus obscuripes Midge MORT LC10 FW 0.00199 166772 Insecta Diptera Chaoboridae Chaoborus obscuripes Midge IMBL EC10 FW 0.00457 166772 Insecta Diptera Chironomidae Chironomus riparius Midge LGTH NOAEL FW 0.00074 165043 Insecta Diptera Chironomidae Chironomus riparius Midge LGTH NOAEL FW 0.00215 165043 Insecta Diptera Chironomidae Chironomus tentans Midge BMAS NOAEL FW 0.00044 167874 Insecta Diptera Chironomidae Chironomus tentans Midge SEXR NOAEL FW 0.00044 167874 Insecta Diptera Chironomidae Chironomus tentans Midge SEXR NOAEL FW 0.00044 167874 Insecta Diptera Chironomidae Chironomus tentans Midge SURV NOEC FW 0.00114 110523 Insecta Diptera Chironomidae Chironomus tentans Midge DWGT NOEC FW 0.00114 110523 Insecta Diptera Chironomidae Chironomus tentans Midge DWGT NOEC FW 0.00117 110523 Insecta Diptera Chironomidae Chironomus tentans Midge DWGT EC25 FW 0.00208 110523

188

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Insecta Diptera Chironomidae Chironomus tentans Midge MORT LC25 FW 0.00303 110523 Insecta Diptera Chironomidae Chironomus tentans Midge MORT LC25 FW 0.00312 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SEXR NOAEL FW 0.00346 110523 Insecta Diptera Chironomidae Chironomus tentans Midge TEMR NOAEL FW 0.00346 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SEXR NOAEL FW 0.00346 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SURV NOEC FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge DWGT NOEC FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SURV NOEC FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge DWGT NOEC FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SEXR NOAEL FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge TEMR NOAEL FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SEXR NOAEL FW 0.00347 110523 Insecta Diptera Chironomidae Chironomus tentans Midge SURV NOEC FW 0.00357 110523 Insecta Diptera Culicidae Aedes aegypti Yellow HTCH LOAEL FW 0.105 168962 Fever Mosquito Insecta Diptera Culicidae Aedes aegypti Yellow SURV NOAEL FW 0.15 168322 Fever (ppm) Mosquito Insecta Diptera Culicidae Aedes aegypti Yellow SURV LOAEL FW 1.5 168322 Fever (ppm) Mosquito Insecta Diptera Tipulidae Tipula sp. Cranefly MORT NOAEL FW 0.012 101963 Insecta Diptera Tipulidae Tipula sp. Cranefly MORT LC10 FW 0.0162 101962 Insecta Diptera Tipulidae Tipula sp. Cranefly MORT NOEL FW 0.093 101962

189

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Insecta Diptera Tipulidae Tipula sp. Cranefly MORT NOAEL FW 1.28 101963 Insecta Diptera Tipulidae Tipula sp. Cranefly MORT NOAEL FW 11 102512 Insecta Diptera Tipulidae Tipula sp. Cranefly MORT NOAEL FW 18 166553 Insecta Ephemeroptera Baetidae Cloeon dipterum Mayfly IMBL EC10 FW 0.000033 166772 Insecta Ephemeroptera Baetidae Cloeon dipterum Mayfly MORT LC10 FW 0.000041 166772 Insecta Ephemeroptera Caenidae Caenis horaria Mayfly IMBL EC10 FW 0.000024 166772 Insecta Ephemeroptera Caenidae Caenis horaria Mayfly MORT LC10 FW 0.000235 166772 Insecta Heteroptera Pleidae Plea minutissima Water Bug IMBL EC10 FW 0.00203 166772 Insecta Heteroptera Pleidae Plea minutissima Water Bug MORT LC10 FW 0.00435 166772 Insecta Megaloptera Sialidae Sialis lutaria Alderfly IMBL EC10 FW 0.00128 166772 Insecta Megaloptera Sialidae Sialis lutaria Alderfly MORT LC10 FW 0.0251 166772 Insecta Plecoptera Pteronarcyidae Pteronarcys dorsata Stonefly MORT NOAEL FW 0.012 101963 Insecta Plecoptera Pteronarcyidae Pteronarcys dorsata Stonefly MORT LC10 FW 0.0208 101962 Insecta Plecoptera Pteronarcyidae Pteronarcys dorsata Stonefly MORT NOAEL FW 0.024 101962 Insecta Plecoptera Pteronarcyidae Pteronarcys dorsata Stonefly MORT NOAEL FW 1.28 101963 Insecta Plecoptera Pteronarcyidae Pteronarcys dorsata Stonefly MORT NOAEL FW 11 102512 Insecta Plecoptera Pteronarcyidae Pteronarcys dorsata Stonefly MORT NOAEL FW 18 166553 Malacostraca Amphipoda Gammaridae Gammarus pulex Scud IMBL EC10 FW 0.00295 166772 Malacostraca Amphipoda Gammaridae Gammarus pulex Scud MORT LC10 FW 0.00577 166772 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT NOEC FW 0.00115 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT EC25 FW 0.00222 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MORT LC25 FW 0.00231 110523

190

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MORT LC25 FW 0.00339 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SURV NOEC FW 0.00344 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SURV NOEC FW 0.00353 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SURV NOEC FW 0.00353 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MORT LC25 FW 0.00423 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT EC25 FW 0.00622 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT EC25 FW 0.00872 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud MORT LC25 FW 0.00941 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT NOEC FW 0.01146 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SEXR NOAEL FW 0.01146 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SEXR NOAEL FW 0.01146 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SURV NOEC FW 0.01193 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT NOEC FW 0.01193 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SEXR NOAEL FW 0.01193 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud REPO NOAEL FW 0.01193 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud REPO NOAEL FW 0.01193 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud SEXR NOAEL FW 0.01193 110523 Malacostraca Amphipoda Hyalellidae Hyalella azteca Scud DWGT NOEC FW 0.01195 110523 Malacostraca Isopoda Asellidae Asellus aquaticus Aquatic MORT LC10 FW 0.00135 166772 Sowbug Malacostraca Isopoda Asellidae Asellus aquaticus Aquatic IMBL EC10 FW 0.00171 166772 Sowbug Values in bold represent lowest values considered for quantitative or qualitative use in risk assessment.

191

Table C-3. Relevant Acute Toxicity Data for Saltwater Invertebrates Tested with Imidacloprid (Source: ECOTOX, Apical Endpoints, Duration 1-4 d)

Meas. Common End- Conc. LCL UCL Class Order Family Genus Species Of Media Ref # Name Point (mg/L) (mg/L) (mg/L) Effect Phylum: Arthropoda Branchiopoda Anostraca Artemiidae Artemia sp. Brine Shrimp MORT LC50 SW 361.23 307.83 498.09 18476 Branchiopoda Anostraca Artemiidae Artemia sp. Brine Shrimp MORT LC50 SW 361.23 307.83 498.09 19639 Insecta Diptera Culicidae Aedes taeniorhynchus Mosquito MORT LC50 SW 0.013 0.01 0.016 18476 Insecta Diptera Culicidae Aedes taeniorhynchus Mosquito MORT LC50 SW 0.013 0.01 0.016 19639 Insecta Diptera Culicidae Aedes taeniorhynchus Mosquito MORT LC50 SW 0.021 0.017 0.03 19639 Malacostraca Decapoda Palaemonidae Palaemonetes pugio Daggerblade MORT LC50 SW 0.3088 0.2736 0.3486 102582 Grass Shrimp Malacostraca Decapoda Palaemonidae Palaemonetes pugio Daggerblade MORT LC50 SW 0.5635 0.4781 0.6642 102582 Grass Shrimp Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 0.010 0.006381 0.01579 152973 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 0.010 0.006381 0.01579 161498 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 0.3127 0.2224 0.4399 152973 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 0.3127 0.2224 0.4399 161498 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 0.8167 0.6929 0.9626 152973 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 0.8167 0.6929 0.9626 161498 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 1.112 0.8419 1.468 152973 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LC50 SW 1.112 0.8419 1.468 161498 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LOAEL SW 0.0048 152973 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MOLT LOAEL SW 0.0048 152973

192

Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MMPH NOAEL SW 0.0048 161498 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MOLT NOAEL SW 0.0048 161498 Malacostraca Decapoda Portunidae Callinectes sapidus Blue Crab MORT LOAEL SW 0.0048 161498

Phylum: Mollusca Bivalvia Veneroida Veneridae Katelysia opima Marine MORT LC50 SW 15.4 169134 Bivalve Gastropoda Architaenioglossa Ampullariidae Marisa cornuarietis Snail FORM NOAEL SW 50 112105 Gastropoda Architaenioglossa Ampullariidae Marisa cornuarietis Snail FORM NOAEL SW 50 112105 Gastropoda Architaenioglossa Ampullariidae Marisa cornuarietis Snail HTRT NOAEL SW 10 112105 Gastropoda Architaenioglossa Ampullariidae Marisa cornuarietis Snail HTCH NOAEL SW 50 112105 Gastropoda Architaenioglossa Ampullariidae Marisa cornuarietis Snail MORT NOAEL SW 50 112105 Gastropoda Architaenioglossa Ampullariidae Marisa cornuarietis Snail WGHT NOAEL SW 50 112105 Values in bold represent lowest values considered for quantitative or qualitative use in risk assessment.

Table C-4. Relevant Acute Toxicity Data for Freshwater Vertebrates Tested with Imidacloprid (Source: ECOTOX, Apical Endpoints, Duration 1-4 d)

Common Meas. End- Conc. LCL UCL Class Order Family Genus Species Media Ref # Name Of Effect Point (mg/L) (mg/L) (mg/L) Montevideo Amphibia Anura Hylidae Hypsiboas pulchellus Tree Frog MORT LC50 FW 52.6 48.4 58.1 168449 Montevideo Amphibia Anura Hylidae Hypsiboas pulchellus Tree Frog MORT LC50 FW 56.7 27.5 116.9 168449 Montevideo Amphibia Anura Hylidae Hypsiboas pulchellus Tree Frog MORT LC50 FW 58.2 26.4 127.8 168449 Montevideo Amphibia Anura Hylidae Hypsiboas pulchellus Tree Frog MORT LC50 FW 69.4 62.8 75.522 168449 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio MORT LC50 FW 214 202 230 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio MORT LC50 FW 241 224 257 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 408 308 524 150163 193

Common Meas. End- Conc. LCL UCL Class Order Family Genus Species Media Ref # Name Of Effect Point (mg/L) (mg/L) (mg/L) Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 502 388 630 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 626 472 788 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 626 476 782 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 732 550 932 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 760 574 970 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 826 614 1106 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 1150 972 1336 150163 Actinopterygii Cypriniformes Cyprinidae Danio rerio Zebra Danio DVLP EC50 FW 1160 1000 1316 150163

Table C-5. Relevant Chronic Toxicity Data for Freshwater Vertebrates Tested with Imidacloprid (Source: ECOTOX, Apical Endpoints, Duration >4 d)

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Amphibia Anura Hylidae Acris crepitans Cricket SURV LOAEL FW 6.75 166535 Frog Amphibia Anura Hylidae Acris crepitans Cricket MMPH NOAEL FW 6.75 166535 Frog Amphibia Anura Hylidae Acris crepitans Cricket BMAS NOAEL FW 6.75 166535 Frog Amphibia Anura Hylidae Acris crepitans Cricket MMPH NOAEL FW 6.75 166535 Frog Amphibia Anura Hylidae Acris crepitans Cricket SURV LOAEL FW 6.75 166535 Frog Actinopterygii Cypriniformes Cyprinidae Ctenophary idella Grass Carp SURV NOAEL FW 6.75 166535 ngodon Actinopterygii Perciformes Centrarchidae Lepomis macrochirus Bluegill SURV NOAEL FW 6.75 166535

Amphibia Anura Ranidae Lithobates clamitans ssp. Bronze SURV NOAEL FW 6.75 166535 clamitans Frog

194

Meas. Common End- Conc. Class Order Family Genus Species Of Media Ref # Name Point (mg/L) Effect Amphibia Anura Ranidae Lithobates clamitans ssp. Bronze DVLP NOAEL FW 6.75 166535 clamitans Frog Amphibia Anura Ranidae Lithobates clamitans ssp. Bronze DVLP NOAEL FW 6.75 166535 clamitans Frog Amphibia Anura Ranidae Lithobates clamitans ssp. Bronze BMAS NOAEL FW 6.75 166535 clamitans Frog

195

ECOTOX References

100844 Jemec, A., Tisler, T., Drobne, D., Sepcic, K., Fournier, D., and Trebse, P. (2007). Comparative Toxicity of Imidacloprid, of Its Commercial Liquid Formulation and of Diazinon to a Non-Target Arthropod, the Microcrustacean Daphnia magna. Chemosphere 68: 1408-1418.

101958 Paul A; Harrington LC; Scott JG. (2006). Evaluation of Novel Insecticides for Control of Dengue Vector Aedes aegypti (Diptera: Culicidae). J. Med. Entomol. 43(1): 55-60.

101962 Kreutzweiser, D. P., Good, K. P., Chartrand, D. T., Scarr, T. A., and Thompson, D. G. (2008). Toxicity of the Systemic Insecticide, Imidacloprid, to Forest Stream Insects and Microbial Communities. Bull. Environ. Contam. Toxicol. 80: 211-214.

101963 Kreutzweiser, D., Good, K., Chartrand, D., Scarr, T., and Thompson, D. (2007). Non-Target Effects on Aquatic Decomposer Organisms of Imidacloprid as a Systemic Insecticide to Control Emerald Ash Borer in Riparian Trees. Ecotoxicol. Environ. Saf. 68: 315-325.

101983 Segura, C., Zaror, C., Mansilla, H. D., and Mondaca, M. A. (2008). Imidacloprid Oxidation by Photo-Fenton Reaction. J. Hazard. Mater. 150: 679-686.

102512 Kreutzweiser, D. P., Good, K. P., Chartrand, D. T., Scarr, T. A., and Thompson, D. G. (2008). Are Leaves that Fall from Imidacloprid-Treated Maple Trees to Control Asian Longhorned Beetles Toxic to Non-Target Decomposer Organisms? J. Environ. Qual. 37: 639-646.

102580 Alexander, A. C., Culp, J. M., Liber, K., and Cessna, A. J. (2007). Effects of Insecticide Exposure on Feeding Inhibition in Mayflies and Oligochaetes. Environ. Toxicol. Chem. 26: 1726-1732.

102582 Key, P., Chung, K., Siewicki, T., and Fulton, M. (2007). Toxicity of Three Pesticides Individually and in Mixture to Larval Grass Shrimp (Palaemonetes pugio). Ecotoxicol.Environ. Saf. 68: 272- 277.

109202 Beketov, M. A. and Liess, M. (2008). Potential of 11 Pesticides to Initiate Downstream Drift of Stream Macroinvertebrates. Arch. Environ. Contam. Toxicol. 55: 247-253.

110523 Stoughton, S. J.; Liber, K.; Culp, J., and Cessna, A. (2008). Acute and Chronic Toxicity of Imidacloprid to the Aquatic Invertebrates Chironomus tentans and Hyalella azteca Under Constant- and Pulse-Exposure Conditions. Arch. Environ. Contam. Toxicol. 54(4): 662-673.

112105 Sawasdee, B. and Kohler, H. R. (2009). Embryo Toxicity of Pesticides and Heavy Metals to the Ramshorn Snail, Marisa cornuarietis (Prosobranchia). Chemosphere 75: 1539-1547.

150031 Lukancic, S.; Zibrat, U.; Mezek, T.; Jerebic, A.; Simcic, T., and Brancelj, A. (2010). Effects of Exposing Two Non-Target Crustacean Species, Asellus aquaticus L., and Gammarus fossarum Koch., to Atrazine and Imidacloprid. Bull. Environ. Contam. Toxicol. 84(1): 85-90.

150163 Tisler, T.; Jemec, A.; Mozetic, B., and Trebse, P. (2009). Hazard Identification of Imidacloprid to Aquatic Environment. Chemosphere 76(7): 907-914.

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152279 Yokoyama, A.; Ohtsu, K.; Iwafune, T.; Nagai, T.; Ishihara, S.; Kobara, Y.; Horio, T., and Endo, S. (2009). A Useful New Insecticide Bioassay Using First-Instar Larvae of a Net-Spinning Caddisfly, Cheumatopsyche brevilineata (Trichoptera: Hydropsychidae). J. Pestic. Sci. 34(1): 13-20.

152830 Lukancic S; Zibrat U; Mezek T; Jerebic A; Simcic T; Brancelj A. (2010). A New Method for Early Assessment of Effects of Exposing Two Non-Target Crustacean Species, Asellus aquaticus and Gammarus fossarum, to Pesticides, a Laboratory Study. Toxicol. Ind. Health 26(4): 217-228.

152973 Osterberg, J. S. (2010). Ecotoxicology of Natural and Anthropogenic Extreme Environments. Ph.D. Thesis, Duke University, Raleigh, NC: 178 p.

153560 Ashauer, R.; Caravatti, I.; Hintermeister, A., and Escher, B. I. (2010). Bioaccumulation Kinetics of Organic Xenobiotic Pollutants in the Freshwater Invertebrate Gammarus pulex Modeled with Prediction Intervals. Environ. Toxicol. Chem. 29(7): 1625-1636.

153561 Ashauer, R.; Hintermeister, A.; Potthoff, E., and Escher, B. I. (2011). Acute Toxicity of Organic Chemicals to Gammarus pulex Correlates with Sensitivity of Daphnia magna Across Most Modes of Action. Aquat. Toxicol. 103(1/2): 38-45.

157949 Hayasaka, D.; Korenaga, T.; Sanchez-Bayo, F., and Goka, K. (2012). Differences in Ecological Impacts of Systemic Insecticides with Different Physicochemical Properties on Biocenosis of Experimental Paddy Fields. Ecotoxicology 21(1): 191-201.

157951 Hayasaka, D.; Korenaga, T.; Suzuki, K.; Saito, F.; Sanchez-Bayo, F., and Goka, K. (2012). Cumulative Ecological Impacts of Two Successive Annual Treatments of Imidacloprid and Fipronil on Aquatic Communities of Paddy Mesocosms. Ecotoxicol. Environ. Saf. 80: 355-362.

157952 Hayasaka, D.; Korenaga, T.; Suzuki, K.; Sanchez-Bayo, F., and Goka, K. (2012). Differences in Susceptibility of Five Cladoceran Species to Two Systemic Insecticides, Imidacloprid and Fipronil. Ecotoxicology 21(2): 421-427.

159937 Loureiro, S.; Svendsen, C.; Ferreira, A. L. G.; Pinheiro, C.; Ribeiro, F., and Soares, A. M. V. M. (2010). Toxicity of Three Binary Mixtures to Daphnia magna: Comparing Chemical Modes of Action and Deviations from Conceptual Models. Environ. Toxicol. Chem. 29(8): 1716-1726

160124 Bottger, R.; Feibicke, M.; Schaller, J., and Dudel, G. (2012). Effects of Low-Dosed Imidacloprid Pulses on the Functional Role of the Caged Amphipod Gammarus roeseli in Stream Mesocosms. Ecotoxicol. Environ. Saf. 81: 49-54.

160293 LeBlanc, H. M. K.; Culp, J. M.; Baird, D. J.; Alexander, A. C., and Cessna, A. J. (2012). Single Versus Combined Lethal Effects of Three Agricultural Insecticides on Larvae of the Freshwater Insect Chironomus dilutus. Arch. Environ. Contam. Toxicol. 63(3): 378-390

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162193 Pestana, J. L. T.; Loureiro, S.; Baird, D. J., and Soares, A. M. V. M. (2010). Pesticide Exposure and Inducible Antipredator Responses in the Zooplankton Grazer, Daphnia magna Straus. Chemosphere 78(3): 241-248.

165043 Azevedo-Pereira, H. M. V. S.; Lemos, M. F. L., and Soares, A. M. V. M. (2011). Behaviour and Growth of Chironomus riparius Meigen (Diptera: Chironomidae) Under Imidacloprid Pulse and Constant Exposure Scenarios. Water Air Soil Pollut. 219(1-4): 215-224.

166535 Ade, C. M.; Boone, M. D., and Puglis, H. J. (2010). Effects of an Insecticide and Potential Predators on Green Frogs and Northern Cricket Frogs. J. Herpetol. 44(4): 591-600.

166553 Kreutzweiser, D. P.; Thompson, D. G., and Scarr, T. A. (2009). Imidacloprid in Leaves from Systemically Treated Trees May Inhibit Litter Breakdown by Non-Target Invertebrates. Ecotoxicol. Environ. Saf. 72(4): 1053-1057.

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166772 Roessink, I.; Merga, L. B.; Zweers, H. J., and Van Den Brink, P. J. (2013). The Neonicotinoid Imidacloprid Shows High Chronic Toxicity to Mayfly Nymphs. Environ. Toxicol. Chem. 32(5): 1096-1100.

167874 LeBlanc, H. M. K. (2011). Single and Combined Effects of the Agricultural Insecticides Chlorpyrifos, Imidacloprid and Dimethoate on Freshwater Insect Larvae. M.S. Thesis, University of New Brunswick, Canada: 113 p.

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168322 Tome, H. V.; Pascini, T. V.; Dangelo, R. A. C.; Guedes, R. N. C., and Martins, G. F. (2014). Survival and Swimming Behavior of Insecticide-Exposed Larvae and Pupae of the Yellow Fever Mosquito Aedes aegypti. Parasites Vectors 7(1): 17 p.

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168962 Antonio-Arreola, G. E.; Lopez-Bello, R.; Romero-Moreno, D. K., and Sanchez, D. (2011). Laboratory and Field Evaluation of the Effects of the Neonicotinoid Imidacloprid on the Oviposition Response of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae). Mem. Inst. Oswaldo Cruz 106(8): 997-1001.

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Appendix D: Additional Details on Modelling Approaches

Application Timing

Timing of application for treated seeds is set at expected seeding or planting dates of the crop. In modeling treated seeds, planting time was set to be seven days before the emergence date specified in the scenario representing the crop use pattern. For seedlings of fruiting vegetables, cucurbit vegetables, and tobacco, imidacloprid is applied in the nursery using a procedure, such as soil drench, without any loss of gravitational water through the pot and planting media (along with the pesticide) is transferred into the field. In addition, the pesticide may be applied to seedlings as basal soil drench during transplanting. Therefore, transplant timing is the time for application used in modeling transplanted crops; application rate in this case equals the rate applied at the nursery and/or the soil drench applied at transplant. In modeling, application for potato pieces is set to be the planting time of the scenario for potato and usual field planting time of citrus plantlets.

For each use pattern, an application window was established by determining the absolute (specified date) or relative (e.g., relative to emergence) first day in which the application starts and the day in which the last application will occur. The following process was executed to establish the application windows for various imidacloprid use patterns:

(1) Data related to application timing were summarized, from the labels; and

(2) Based on this data and available information from the literature, two procedures were used to deal with application timing: The First procedure was for use patterns with time restricted agronomic practices such as field crops (i.e., the vegetable and field crops use patterns) and the Second procedure was used for use patterns in which the application window may extend throughout the year (i.e., tree crops and turf). In the First procedure, an application window was established along with several application schedules prior to modeling (batch runs) to cover the application window. In this case, required exposure EECs were generated for more than one possible application schedule throughout the application window. In the Second procedure, a batch run was executed for a period of a year starting from the possible first application date and exposure EECs were obtained after modeling (batch runs) for applications that may occur throughout the application window by deleting EECs generated for timing outside that window. Table D-1 and Table D-2 contain summaries of data used for the above described exercise followed by examples.

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Table D-1. Data Used to Determine the Application Window During Which One Soil Application May Occur (Application May Occur During Timing Shaded in Green) Use patterns for which the label Use Patterns for which the label specifies specifies the time relative to planting that application may occur at any time Or as: prior to, at or after planting in case of chemigation: Application window Crop (Crop Group /Sub-group) (assumed days relative to scenario should be outside the flowering period and emergence date are stated below) the pre-harvest interval (PHI) specified Prior To At After below -14 -7 7 Flowering Period1 PHI (Days) Artichoke (Globe) No restriction 7 Banana & Plantain No restriction 0 Brassica (5) No restriction 21 Bulb Vegetables (3) No restriction 21 Bushberry (13-07B) 7-Apr to 30-May 7 Caneberry (13-07A) 7-Apr to 30-May 7 California & South Texas 15-Mar to 30-April 0 Citrus (10) Florida 1-Jan to 28-Feb 0 Coffee 7-Mar to 30-May 7 Cotton No restriction None: Applied Early Cranberry (13-07B) 15-May to 15-Jul 30 Cucurbits (9) No restriction 21 Fruiting Vegetables (8) No restriction 21 Grape (13-07F) No restriction 30 Herbs & spices (19) No restriction 14 Hops No restriction 60 Leafy Greens (4A) No restriction 21 Leafy Petioles (4B) No restriction 45 Legumes (6) No restriction 21 Peanuts No restriction 14 Pome Fruits (11) 15-Mar to 15-May 21 Pomegranate 15-May to 15-Jul 0 Potato (1C) No restriction None: Applied Early Root Vegetables (1B) No restriction 21 Stone Fruits (12) 7-Apr to 7-May 21 California 15-Jan to 30-Apr 14 Strawberry (13-07G) Florida 30-Oct to 7-Dec Sugarbeet (1A) (CA only) No restriction None: Applied Early Tobacco No restriction 14 Almonds (14) 7-Feb to 15-Mar 7 Pecans (14) 15-Mar to 30-Apr 7 Tree Nuts (14) Filberts 30-Dec to 7-Feb 7 Tropical Fruits (23 and 24) 15-Dec to 30-Mar 6 Tuberous and Corms: Corm (1D) No restriction 3/125 Tuberous and Corms: Leaves No restriction 3 Poplar-Cottonwood 7-Feb to 15-Apr 0 Watercress (4A) No restriction 21 1Blooming Period References: Citrus: http://lake.ifas.ufl.edu/agriculture/citrus/documents/Samplingcitrusbloomabundance_final.pdf Citrus: http://ipm.ucanr.edu/PMG/C107/m107yi01.html#BLOOM Almonds: http://thealmonddoctor.com/2009/06/22/the-seasonal-patterns-of-almond-production/ Tropical fruits (Mango): http://edis.ifas.ufl.edu/mg216 For Mango

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Filberts: http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/12300/em8987.pdf?sequence=3

Table D-2. Data Used to Determine the Application Window During Which One Or More Foliar Application May Occur (Application May Occur During Timing Shaded in Green) Period Needed for Multiple Application & PHI (Days)1 Crop (Crop Group /Sub-group) For Multiple Application Total For PHI (B) (A) (A+B) Artichoke (Globe) 4 @ 14= 56 7 63 Banana & Plantain 5 @ 14= 70 0 70 Brassica (5) 5 @ 5= 25 7 32 Bulb Vegetables (3) No Foliar Application Bushberry (13-07B) 5 @ 7= 35 3 38 Caneberry (13-07A) 5 @ 7= 35 3 38 Citrus (10) 2 @ 10= 20 0 20 Coffee 5 @ 7= 35 7 42 Cotton 5 @ 7= 35 14 49 Cranberry (13-07A) No Foliar Application Cucurbits (9) No Foliar Application Fruiting Vegetables (8) 3 @ 5= 15 0 15 Grape (13-07F) 2 @ 14= 28 0 28 Herbs & spices (19) 3 @ 5= 15 7 22 Hops 3 @ 21= 63 28 91 Leafy Greens (4A) 5 @ 5= 25 7 32 Leafy Petioles (4B) No Foliar Application Legumes (6) 3 @ 7= 21 7 28 Peanuts 3 @ 5= 15 14 29 Pome Fruits: Pears (11) 2 @ 10= 20 7 27 Pome Fruits: Others (11) 3 @ 10= 30 7 37 Pomegranate 3 @ 7= 21 7 28 Potato (1C) 4 @ 7= 28 7 35 Root Vegetables (1B) 3 @ 5= 15 ? ? Soybeans (6A) 3 @ 7= 21 21 42 Stone Fruits: Apricot, Nectarine & Peach (12) 3 @ 7= 21 7 28 Cherries, Plums, Plumcot, Prune (12) 5 @ 10= 50 7 57 Strawberry (13-07G) 3 @ 5= 15 7 22 Sugarbeet (1) (CA only) No Foliar Application Tobacco 6 @ 7= 42 14 56 Tree Nuts (14) 4 @ 6= 24 7 31 Tropical Fruits (23 and 24) 5 @ 10= 50 10 60 Tuberous and Corms: Corm (1D) 3 @ 5= 15 7 22 Tuberous and Corms: Leaves 3 @ 5= 15 7 22 Poplar-Cottonwood 5 @ 10= 50 0 50 Watercress (4A) 5 @ 5= 25 7 32 1 Example calculation: For Artichoke, foliar application consists of 4 applications with 14 day intervals therefore the time needed to execute these four applications= 4 x 14= 28 days. Additionally, the time needed for PHI= 7 days. This means that the last possible application should occur at least 63 days before harvest.

The following are three examples showing how the application window/dates were selected:

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Example 1: Brassica: Brassica was modeled using two scenarios one for California and the other for Florida. Each run consisted of a combined application of one soil (with the seeds or seedlings) and five foliar applications. Application dates (schedules), for possible applications, were created using the spreadsheet shown in the following table:

Table D-3. Example of Brassica Scenario Run Using Varying Schedules of Application Dates. Representative Scenario CAColeCropRLF_V2 FLcabbageSTD Crop emergence date (from scenario) 1-Jan 16-Oct Crop harvest date (from scenario) 3-Mar 15-Feb Length of the crop season (from scenario) 62 121 Crop emergence date (from scenario) 1-Jan 16-Oct Length of interval (from label) = A 5 days 5 days Number of applications (from label) = B 7 days 7 days Soil application for seeds “seeded crop” (Assume -7 days from emergence) 25-Dec 9-Oct Soil application for seedlings (Assume 7 days after emergence) 8-Jan 23-Oct Start of foliar application series for seeded crop (Assume 7 days after seed soil application) 1-Jan 16-Oct Start of foliar application series for transplanted crop (Assume 7 days after soil application to seedling) 15-Jan 30-Oct Length of the series of foliar applications for the crop= A x B 35 days 35 days Length of Pre-harvest interval “PHI” for the crop (from label) = D 7 7 Total length of the period during which foliar application may NOT start= C+D 42 42 Should NOT start series of foliar applications beyond this date 21-Jan 4-Jan Application Schedule No. 1 for CAColeCropRLF_V2 Application Schedule No. 1 for FLcabbageSTD Seeded Crop Transplanted Crop Seeded Crop Transplanted Crop Soil Application: 25-Dec Soil Application: 8-Jan Soil Application: 9-Oct Soil Application: 23-Oct 1st Foliar Application: 1- Jan 1st Foliar Appl.: 15-Jan 1st Foliar Appl.: 16-Oct 1st Foliar Appl.: 30-Oct 2nd Foliar Appl.: 6-Jan 2nd Foliar Appl.: 20-Jan 2nd Foliar Appl.: 21-Oct 2nd Foliar Appl.: 4-Nov 3rd Foliar Appl.: 11-Jan 3rd Foliar Appl.: 25-Jan 3rd Foliar Appl.: 26-Oct 3rd Foliar Appl.: 9-Nov 4th Foliar Appl.: 16-Jan 4th Foliar Appl.: 30-Jan 4th Foliar Appl.: 31-Oct 4th Foliar Appl.: 14-Nov 5th Foliar Appl.: 21-Jan 5th Foliar Appl.: 4-Feb 5th Foliar Appl.: 5-Nov 5th Foliar Appl.: 19-Nov Application Schedule No. 2 for CAColeCropRLF_V2 Application Schedule No. 2 for FLcabbageSTD Soil Application: 25-Dec Soil Application: 8-Jan Soil Application: 9-Oct Soil Application: 23-Oct 1st Foliar Appl.: 28-Jan 1st Foliar Appl.: 11-Feb 1st Foliar Appl.: 12-Nov 1st Foliar Appl.: 26-Nov 2nd Foliar Appl.: 2-Feb 2nd Foliar Appl.: 16-Feb 2nd Foliar Appl.: 17-Nov 2nd Foliar Appl.: 1-Dec 3rd Foliar Appl.: 7-Feb 3rd Foliar Appl.: 21-Feb 3rd Foliar Appl.: 22-Nov 3rd Foliar Appl.: 6-Dec 4th Foliar Appl.: 12-Feb 4th Foliar Appl.: 26-Feb 4th Foliar Appl.: 27-Nov 4th Foliar Appl.: 11-Dec 5th Foliar Appl.: 17-Feb 5th Foliar Appl.: 2-Mar 5th Foliar Appl.: 2-Dec 5th Foliar Appl.: 16-Dec

Each application schedule was used to execute a run (A modeling run for Application Schedule No. 1 and another run for Application Schedule No. 2) to arrive at several estimates of exposure EECs. EECs for applications near emergence date were selected for risk assessment. This is because the label 204 recommends early applications. In addition, the use pattern for broccoli was modeled for the combined seed plus foliar plus soil application. In this case the same schedules were used with the addition of one soil treatment following the last foliar treatment (refer to Example 1, Appendix B).

Example 2: Bulb vegetables: Only seed and soil treatment are labeled for this use pattern. Absolute dates (for the one application) were calculated for each scenario 14 days before emergence date of the scenario (e.g., CAonion_WirrigSTD= 2-Jan which is 14 days before the 16-Jan emergence date of the scenario; GAOnion_WirrigSTD= 1-Sep which is 14 days before the 15-Sep emergence date of the scenario). Batch runs were executed for application windows of 21 days at 7-day steps giving four estimates of exposure EECs (one each for applications at 2-Jan, 9-Jan, 16-Jan and 23-Jan for CA scenario; and one each for applications at 1-sep, 8-Sep, 15-Sep and 22-Sep for GA scenario). In addition, the use pattern for was modeled for onions; a combined application of treated seeds plus one soil application. In this case the same schedules were used with the addition of one soil treatment sometime after seeding (refer to Example 2, Appendix B).

Example 3: Citrus: Foliar and soil application to citrus were modeled in a batch runs using three scenarios: CAcitrus_WirrigSTD; FLcitrusSTD; STXgrapefruitNMC. Each run was executed for all three scenarios for 150 days’ window in 5-day steps. Each run gave 30 estimated EECs (150-day window/5-day step= 30 estimates) for each of the three scenarios. The absolute date for each of the 30 estimates was calculated and EECs generated for timing outside and established window for citrus were deleted. The highest exposure EECs within the application window were used for this assessment. Pre-determined application window for citrus was established after consideration of various label restrictions concerning flowering period and pre-harvest interval (PHI). Additionally, modeling was executed for transplanted citrus followed by soil or foliar applications (refer to Example 3, Appendix B).

Labeled Application Rates

Use patterns detailed in Appendix A were used to obtain the required parameters for modeling. In most cases, labels for imidacloprid permit combined applications of foliar, soil, and/or seed treatment. Resultant EECs, from combined applications, were estimated because, in most cases, expected exposure EECs for such applications could be higher than single application. In order to execute this step for permitted combined applications, the Agency found that labels were not clear if combined applications of soil, foliar and seed treatment are permitted and if so in which crops/crop groups and what would be the maximum application rates per season and per year. In response to this inquiry, the main registrant sent a modified label of GAUCHO® 550 SC Insecticide in which the following main clarifications were included:

 Seasonal and yearly application rates were clarified by deleting the general statement in page 6 of the label

“Do not apply more than 0.5 lb active ingredient per acre, per year regardless of formulation or method of application, unless specified within a crop-specific section for a given crop”.

Instead, seasonal and yearly rates were specified for each crop or crop group;

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 Seasonal application rates were specified to equal the yearly rates for some crops but three seasons/year of application were specified for the following crops groups: Brassica, Cucurbits, Herbs & Spices, Leafy greens, Leafy petiolate, Legumes (except soybean), Strawberry and Tuberous corm vegetables; and

 Possible combined seasonal rates were specified for each crop or crop sub-group stating what may be combined (seed, foliar and/or soil applications) regardless of the formulation type. Examples of restrictions, on application rates, varied from crop/crop group-subgroup and hereunder are examples of such label restrictions: group

o For peanuts, the label states “Regardless of formulation or method of application, apply no more than 0.5 lb. active ingredient per acre per year, including seed treatment, soil and foliar uses”; o For tobacco, the label states: “Regardless of formulation or method of application, apply no more than 0.5 lb. active ingredient per acre per year, including tray drench, soil and foliar uses”; o For cucurbits, which has no foliar application, the label states: “Regardless of formulation or method of application, apply no more than 0.4 lb. active ingredient per acre per crop season, including planthouse and soil uses. Maximum crop seasons per year: 3”; and o For fruiting vegetables, which have no seed treatment use, the label states “Regardless of formulation or method of application, apply no more than 0.5 lb. active ingredient per acre per crop season, including planthouse, soil and foliar uses”.

Based on this modified label, it was clear that combined applications are permitted with three important restrictions, namely: specifying types of applications that may be combined (i.e., seed/seedling treatment, soil and/or foliar), the maximum combined seasonal rates, and how many seasons/year; the latter gives the maximum yearly rate. Although possible, combined applications were clarified, necessary modifications to the individual rates for most of the use patterns were not specified. For example: in Artichoke, the label permits soil application at a maximum of 0.5 lb. a.i/A, foliar application at a maximum of 0.5 lb. a.i/A, and combined soil plus foliar applications at a restricted maximum rate of 0.5 lb. a.i/A/season for only one season/year (means an application of 0.5 lb. a.i/A/ season or year). In order to abide by the seasonal/yearly rate of 0.5 a.i/A, no combination can be achieved at the maximum rate of foliar and soil and a reduction in the rate for one or both is necessary.

Examination of imidacloprid labels indicates that the maximum rate may range from 0.07 to 0.50 lb. a.i/A for seed/seedling, from 0.18 to 0.5 lb. a.i/A (in one application), from 0.10 to 0.5 (in one to six applications). By using the lower rates (within the application ranges stated above), many combinations of soil and foliar applications may be obtained such as: one soil application at 0.125 lb. a.i/A plus three foliar applications of 0.125 lb. a.i/A (0.125x 3= 0.375); a total of 0.5 lb. a.i/A per season or year (0.125+0.375). However, it is important to point out that it is difficult to predict what kind of a combined application will be selected by the farmer as it is expected to vary depending on such factors as application cost, timing of pest pressure, available application equipment, and soil and weather conditions among many others. From preliminary modeling runs, it was noted that, in most cases, the lowest EECs are expected to result from the combined rate achieved by reducing the rate for foliar

206 application, while the highest EECs will result from the combined rate achieved by reducing the rate for soil application. This is because soil application places most or all of the pesticide mass below the 2 cm runoff extraction zone of the model (reduce mass of pesticide carried by runoff). To deal with this problem of choosing the application rates for the combined applications, the Agency conservatively used the reduction in the soil application rate, when possible.

For seed treatment applications, one of the limiting factor in modeling exposure EECs from treated seeds is the seeding depth. The model estimates no exposure (i.e. EECs= zeros) for seeds planted at depths >2 cm. Canola, flax/crambe and sorghum were the only seed use pattern modeled alone while others were modeled in combination with soil and/or foliar applications.

Modeling for imidacloprid use on cranberry

Cranberries can be grown in a dry field or flooded bog setting which is flooded as part of agricultural management practices for its harvest production. Cranberry EECs over a dry field are calculated using Oregon Berries surrogate crop scenario in conjunction with Providence, RI weather data. The crop scenario and weather data, stated above, are expected to depict representative land surface and weather conditions over the Cape Cod region, where a large portion of cranberry production occurs.

To address exposure to aquatic organisms within bog settings where the applications occur, the recently implemented PFAM model (version 2, dated Sept. 28, 2016) provides upper-bound (one-in-ten year) estimates of imidacloprid surface water EECs within the bogs. For cranberry bogs, flooding occurs during harvesting. Furthermore, information from the State of Massachusetts, where a large portion of cranberry production occurs, indicates that the current industry standard is to flood fields during the wintertime to prevent damage incurred from freezing. Prior to flooding, imidacloprid residues are metabolized partially at a rate dictated by the aerobic soil metabolism input parameter (half-life = 254 days, see Table 3-4). Following field flooding, imidacloprid residues are metabolized in the water column at a rate dictated by the aerobic aquatic metabolism input parameter (half-life = 236 days, see Table 3-4) but somewhat more rapid in benthic environments (half-life = 81 days, see Table 3-4).

41 During flooding, it is industry practice to fill the bog with water to a depth of 12 inches40F . No water volume turnover cycle is assumed to be a reasonable scenario for the harvesting period, as water is often held within the bog throughout the harvesting period. The same scenario with no water turnover is maintained during the wintertime flooding period as these conditions allow the water to freeze and create an insulating protective barrier for the cranberry bushes.

The same chemical fate parameterization as the PWC modeling, is used in PFAM to evaluate aquatic exposure impacts from imidacloprid applications. PFAM parameters related to application-specific and flood scheduling input associated with cranberry use sites is shown in Table D-4.

41 URL: http://www.umass.edu/cranberry/pubs/bmp_flood_mgt.html 207

Table D-4. PFAM Input Parameters for Imidacloprid Application and Cranberry Bog Flooding Events. Flooding Events: Calendar Dates, Flood Onset Pesticide Application Event Use and Weather Characteristics, Bog Water Replacement/Turnover Rate, Application Station (App. Rate, Calendar Date, and Water Depth Site Location and App. Method) Harvest Flooding Wintertime Flooding Dates: October 1 – 3 Dates: December 1 – January 13 Rate: 0.50 lbs a.i./A Cranberry Water Turnover: None Water Turnover: None Providence, RI Method: Foliar Ground Spray (Flooded Bog) Flood Onset: Sharp Flood Onset: Sharp App. Date: August 8 Water Depth: 12” Water Depth: 12” 1Maximum single application rate modeled based on all product labels collectively. 2Flooding practices known for cranberry production practices (UMASS Amherst Cranberry Station)

Modeling for imidacloprid use on watercress

Watercress is a crop grown in a wetland field setting which is flooded as part of agricultural management practices for its production. To address exposure to aquatic organisms associated with these management practices, the recently implemented PFAM model provides estimates of imidacloprid surface water EECs in the wetland water body where watercress is grown. For watercress, preliminary information indicates current industry standard is to hold water or prevent water flow through for a period of time after pesticide applications. Therefore, EECs are derived by applying imidacloprid to a dry field with watercress present. Refer to Table D-5 for the application cycle evaluated following maximum application rates, number of applications, and application intervals specified on the label.

Following known management practices with watercress production, the field is re-flooded to a depth of 42 2 inches 24 hours after the last application (McHugh et al., 1987)41F . At the time of flooding, available imidacloprid residues in the soil equilibrate with the flood waters. Prior to flooding, imidacloprid residues are metabolized partially at a rate dictated by the aerobic soil metabolism input parameter (half-life = 254 days, see Table 3-4). Following field flooding, imidacloprid residues are metabolized in the water column at a rate dictated by the aerobic aquatic metabolism input parameter (half-life = 236 days, see Table 3-4) but somewhat more rapid in benthic environments (half-life = 81 days, see Table 3-4). A paddy water volume turnover cycle of 8 cycles a day is assumed to be a reasonable value for the flushing periods before and after the application cycle, given the rapid throughput of water likely to occur through an open wetland.

The same fate parameterization as the PWC modeling, shown in Table 3-4, is used in PFAM to evaluate aquatic exposure impacts from imidacloprid watercress applications. PFAM parameters related to application-specific and flood scheduling input associated with watercress use is shown in Table D-5.

42 McHugh, J.J. Jr., Fukuda S.K., and Takeda, K.Y. 1987. Hawaii Watercress Production. University of Hawaii College of Tropical Agriculture and Human Resource Research Extension Series Publication 088. Honolulu, HI. URL (Accessed on-line September 2016): http://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-088.pdf 208

Table D-5. PFAM Input Parameters for Imidacloprid Application to Watercress Flooding3 and Pesticide Application Events Application/Flooding Events 1 2 3 4 5 6 7 8 Flooding Dates 2 days before 1 day after

(Days relative to pesticide app.)2 first app. last app. Pesticide Retreatment Intervals 1 1st App., 5 days, 5 days, 5 days, 5 days, 5 days, (Days after Previous App.), App. 0.26, 0.047, 0.047, 0.047, 0.047, 0.047, Rate “lbs a.i/A”, and Method Ground Aerial Aerial Aerial Aerial Aerial Flooding Dates 2 8-Jun 6-Jul Pesticide Application Dates 1 10-Jun 15-Jun 20-Jun 25-Jun 30-Jun 5-Jul 1Maximum single application rate modeled based on all product labels collectively; weather station = Knoxville, TN 2Flooding practices known for watercress crop management practices (McHugh et al., 1987). 3Sharp flooding onset and turnover rate = 8 cycles per day evaluated for both the pre and post-application flooding event.

Modeling for imidacloprid residential and commercial uses

Use patterns in Appendix A were used to obtain the required application rates and other information needed for modeling. In order to simulate applications to residential and commercial areas, where the entire field size will not be treated and where the land will be covered by both pervious and impervious surfaces, multiple PWC simulations are performed and the time series are combined (each daily EEC from different time series outputs are added) from the simulations to obtain a final set of exposure estimates for the simulated area. The scenarios simulated and combined and the application rates assumed are described in more detail below.

The “residential” and various other “urban” use patterns (e.g., commercial) require the PRZM Residential, Right-of-Way (ROW), and Impervious scenarios for modeling. The PRZM impervious scenario may be used in the Tier 2 coupled aquatic models PRZM/VVWM (using the PWC v.1.52 graphical user interface) along with the residential and/or other appropriate pervious scenario such as ROW to obtain EECs. Each of the scenarios is run separately. This approach assumes that no watershed is completely covered by either the ¼ acre lot (the basis for the residential scenario) or undeveloped land (the basis for the ROW scenario), for residential and ROW use patterns, respectively. By modeling a separate scenario for impervious surfaces, it is also possible to estimate the amount of exposure that could occur when the pesticide is applied or over-sprayed onto this surface. Using two (e.g., impervious and ROW, or impervious and residential) or three scenarios (e.g., impervious, residential and ROW) in tandem requires post-processing of the modeled output in order to derive a weighted EEC that represents the contribution of both the pervious (i.e., residential and ROW) and the impervious surfaces. Daily EECs from these scenarios can also be weighted and aggregated. The residential pervious and impervious scenarios are parameterized to represent certain California or Texas urban sites. Therefore, for modeling uses in other metropolitan regions not located in California or Texas, the residential pervious (residential, ROW) and impervious scenarios can be run with meteorological files from other locations of the U.S.

Homeowner/Residential Urban Exposure Modelling Assumptions

The USEPA developed a standard residential exposure scenario using a quarter acre residential lot

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(10,890 ft2), with houses with a 1000 ft2 footprints, based upon certain Organophosphate Endangered Species Assessments (OP ESAs) work being developed by the Agency. Houses are assumed to be square with sides of 31.6 feet and a 15 feet wide driveway to the house (Figure D-1)

Figure D-1. Residential Conceptual Model of Imidacloprid Applications (Not To Scale)

The perimeter of the house that is treated on sod or lawn (pervious surfaces) within 5 feet of the house foundation is defined by the following equation.

퐻표푢푠푒 푝푒푟푖푚푖푡푒푟 푎푟푒푎 = (31.6 ft × 2 sides + (31.6 ft + 10 ft) × 2 sides − 15 ft driveway) × 5 ft = 657 ft2

Where 31.6 ft is the length of the house; and 10 ft is twice the perimeter widths to account for the additional corner areas of the perimeter. The total area of treatment related to the pervious area from perimeter treatment is 657 ft2 (6.03% of the quarter acre lot).

Imidacloprid homeowner use, however, is not limited to perimeter treatment and also includes vegetation, and ornamental vegetation (e.g., trees, shrubs and non-bearing fruit and nut trees). To address these additional uses, additional treated surfaces have been added to the standard residential exposure scenario. To address these applications simplifying assumptions were made. It is assumed that the sum of the list of uses encompasses 1,000 ft2 on a quarter acre lot (9.18% area treated). This is represented in Figure D-1 by ten 100 ft2 squares and is modeled using the Rights-of-Way scenario.

To address applications to home gardens (e.g., ground covers, evergreens, flowering/foliage plants, foliage plants, roses, and small trees & shrubs), the Health Effects Division’s recommended point estimate for garden size of 1,200 ft2 is used (USEPA, 2012). This garden size fits reasonably within the established quarter acre lot seen in Figure D-1 and is modeled using the PRZM Residential scenario

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(Curve number = 83).

For the Impervious scenario, there is no modeled area of application on a given lot, since imidacloprid is not for use on impervious surfaces in residential settings.

For modeling purposes, all uses with like scenarios and like application rates are summed. House perimeter treatments, and ornamentals are modeled with the Rights-of-Way scenario. As calculated above, house perimeter treatment accounts for 6.03% of the quarter acre lot. Ornamentals account for 1,000 ft2 of treated area or 9.18% of the quarter acre lot. Together, these Rights-of-Way PRZM scenario uses account for 15.2% of the total area of the quarter acre lot. The garden use accounts for 1,200 ft2 of treated area or 11.0% of the quarter acre lot, which is the use modelled by the Residential PRZM scenario. Table D-6 summarizes theses uses and adjusted percent area treated or percent use areas.

Table D-6. Percent Area Treated for the Residential Lot ID\PRZM Scenario Residential Rights-of-Way Impervious House perimeter treatment (6.03%) 0.40 lb a.i./A Ground covers, evergreens, Ornamental vegetation (e.g., flowering/foliage plants, foliage trees, shrubs and non-bearing plants, roses, and small trees & Included uses fruit and nut trees) (9.18%) 0.50 N/A shrubs (Garden) lb a.i./A (1200 ft2/10890 ft2) (100) It is assumed that 0.50 lb a.i./A 0.50 lb a.i./A covers the application rate for both uses. Percent Area Treated 11.0% 15.2% 0%

Commercial/Institutional Urban Exposure Modelling Assumptions

An urban exposure conceptual model was developed to assess exposure to imidacloprid from urban use sites where applications may occur. Use of this conceptual model is considered more realistic than assuming that the entire watershed is treated with imidacloprid (i.e., the entire watershed consists of a specified surface and it is treated at the maximum rate). Instead, specific areas of the quarter acre lot are treated. For the commercial lots, the assumption is that the commercial non-agricultural buildings or areas (i.e., the footprint) may also be represented by a scenario resembling the residential lots previously described (Figure D-2). Exposure estimates for each non-agricultural use are derived individually. In some cases, an aggregation of multiple scenarios (pervious or impervious) was used in a summation approach. The summation is done by means of an Excel spreadsheet file. An explanation of the assumptions for building perimeter for model simulation is provided below.

The urban exposure conceptual model (Figure D-2) consists entirely of quarter acre (10,890 ft2; 104.36 ft x 104.36 ft) lots. Each lot contains one 1000 ft2 commercial or institutional building. The building is assumed to be a square with sides of 31.6 feet, with three doors, one of which is in the back of the building, leading to the trash storage area as depicted in (Figure D-2). The building is surrounded by grassy and ornamentals landscape 5 ft wide (landscape ornamentals: around the perimeter of industrial and commercial buildings), which in turn is surrounded by a parking lot and a driveway. The contribution or adjusted percent area treated of each of the corresponding imidacloprid uses is

211 described below.

Figure D-2. Urban Lot Conceptual Model of Imidacloprid Applications (not to scale).

Calculation of the adjusted percent area treated for outdoor commercial applications of pyrethroids is based on a 5 feet perimeter band (soil broadcast; pervious surface) treatment adjacent to a building as shown in the following equation.

Perimeter [(31.6 ft × 2 sides) + ((31.6 ft + 10 ft) × 2 sides) − 2.5 ft × 3 doors)] × 5 ft = 694.5 ft2 Percent area treated = 694.5 ft2/10,890 ft2 = 0.0638 = 6.38%

The perimeter treatment was assessed using a post processing strategy to combine contributions that result from application to developed (pervious) and impervious areas, adjusting by the percent area treated. Adjusted percent areas treated are summarized in Table D-7 by use site and urban scenario [impervious or pervious (residential or right-of-way)].

Table D-7. Percent Area Treated for the Commercial Lot Scenario Rights-of- ID\PRZM Scenario Residential Impervious Way Included uses Area in the perimeter of the building (6.38%) 0.40 lb a.i./A N/A N/A Percent Area Treated 6.38% 0% 0%

Number of Quarter Acre Lots in a 10 ha Watershed

An estimate of the number of residential lots in a 10 ha watershed has been previously evaluated for California Red Legged Frog (CRLF) and other endangered species assessments [i.e., Appendix G of

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“Potential Risks of Alachlor Use to Federally Threatened California Red-legged Frog (Rana aurora draytonii) and Delta Smelt (Hypomesus transpacificus)”, USEPA 2009]. The assumption previously made was 58 lots arranged in 10 lot blocks. See D-3 for a general conceptual model of the 10 ha watershed containing 58 lots. Urban Watershed

Figure D-3. Schematic for a Representative Suburban Watershed

There are 10,890 ft2/lot x 58 lots in 10 ha = 631,620 ft2 out of a total of 1,076,391 ft2/ watershed (i.e., 10 ha), the adjustment factor is 0.587. For simplicity, the same adjustment factor is assumed for the commercial lots. The adjusted percent area treated presented in Table D-8 is based on the correction for a factor of 0.587 (i.e., 58.7%).

Table D-8. Adjusted percent area treated of the watershed for each of the available scenarios, and uses included, for the Residential and Commercial lots, assuming 58 quarter acre lots in the 10-ha watershed ID \ PRZM Scenario Residential Rights-of-Way Impervious Adjusted Percent Area Treated 6.46% 8.92% 0% Adjusted Percent Area Treated 3.74% 0% 0%

Other modeling inputs used are summarized in Table D-9.

Table D-9. Imidacloprid Ecological Exposure Assessment Uses, Scenarios, and Application Information Used for Aquatic Exposure in the PWC, Non-crop Use Run Number, PWC Scenario/ Uses Represented Max. App. Rate RESIDENTIAL 01 CA residential: Ground covers, evergreens, flowering/foliage plants, foliage plants, roses, and small trees & shrubs (Garden) 0.560 (0.50) kg 02 CA ROW: House perimeter treatment; Ornamental vegetation (e.g., trees, shrubs and non-bearing a.i./ha fruit and nut trees) (lb a.i/A) 03 BSS residential: Ground covers, evergreens, flowering/foliage plants, foliage plants, roses, and small trees & shrubs (Garden)

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Run Number, PWC Scenario/ Uses Represented Max. App. Rate 04 BSS ROW: House perimeter treatment; Ornamental vegetation (e.g., trees, shrubs and non-bearing fruit and nut trees) 05 CA residential (PA met file, W14751): Ground covers, evergreens, flowering/foliage plants, foliage plants, roses, and small trees & shrubs (Garden) 06 CA ROW (PA met file, W14751): House perimeter treatment; Ornamental vegetation (e.g., trees, shrubs and non-bearing fruit and nut trees) 07 CA residential: (FL met file, W12839): Ground covers, evergreens, flowering/foliage plants, foliage plants, roses, and small trees & shrubs (Garden) 08 CA ROW (FL met file, W12839): House perimeter treatment; Ornamental vegetation (e.g., trees, shrubs and non-bearing fruit and nut trees) COMMERCIAL 09 CA residential: Area in the perimeter of the building 0.448 (0.40) kg a.i./ha 10 CA residential: (FL met file, W12839): Area in the perimeter of the building (lb a.i/A) For all modeling runs, stated below, the maximum number of applications is one, day of first application is 01-Jun, application efficiency= 1, No drift, and applications were assumed to be on soil surface using ground equipment without incorporation. ROW=rights-of-way

Application Methods

Ground, aerial and/or air-blast equipment are used to deliver liquid spray applications to plant foliage (i.e., foliar application). In this case, the application method selected for PWC modeling is “above crop”. For soil application, many methods of ground application are used to deliver imidacloprid formulation into the soil as a liquid spray. Most of the soil application methods are used to place the pesticide below the soil surface and into the seed or root zone of the crop. In order to achieve placement of the pesticide at the proper depth, more than one method may be used depending on the crop and at what stage it is to be treated. These methods may be categorized into two categories depending on the time at which the method may be used.

Category I: Methods may be used shortly before, at, or just after seeding/transplanting (Table D-10).

Table D-10. Labeled Application Methods Used Early in the Crop Growth Stage DSGN1 Application Method (As per Label) I-1 In-furrow spray directed on or below seed: During bedding I-2 In-furrow spray directed on or below seed: During setting or transplant I-3 In-furrow spray directed on or below seed: Over Hulis (plant material) In-furrow spray directed on or below seed: During bedding immediately prior to planting or at the time of I-4 planting Narrow Band Spray (≤2”) directly below the eventual seed row during bedding Or over the seed-line incorporated I-5 to 1-2” by irrigation I-6 Narrow Band Spray directly over the raw covered with ≥ 3” of soil during Hilling I-7 Shanked-in 1 to 2” below seed depth; seed-line; or below Hulis I-8 Drench or Transplant water drench At Or After transplant/seeding: Seeding or Hill drench I-9 Plant-material or plant-hole treatment (just prior to, or during transplanting) 1 DSGN= Designation

Category II: Methods used at any stage of the plant growth (Table D-11):

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Table D-11. Labeled Application Methods Used Early in the Crop Growth Stage DSGN1 Application Method (As per Label) Subsurface side-dress: Sprayed on both sides of the row covered with ≥ 3” of soil Or incorporated into the II-1 root-zone II-2 Subsurface side-dress: Shanked/Injected on both sides of plants/ trees followed by irrigation within 48 hour Drench for trees: Basal soil drench into the base/around trees in sufficient water to insure incorporation into II-3 the entire root-zone followed by irrigation II-4 Drench for trees: For Caneberry with 500 gal. solution/A II-5 Chemigation: Irrigation amount not specified II-6 Chemigation: With 600 to 1,000 gallons of water followed by 0.1 to 0.3” irrigation within 24 hours II-7 Chemigation: On wetted soil followed by 10-20 minutes of additional irrigation Band soil surface spray: On both sides of the tree within the drip-line area of the tree followed immediately II-8 with light sprinkler irrigation into the upper portion of the root-zone Band soil surface spray: On both sides of the row (18” band) to moist soil followed immediately by 0.5 to 1” II-9 of irrigation/rainfall within 24 hours Soil-surface spray application in a minimum of 20 gallons of water/A followed by 0.25” of rainfall or irrigation II-10 water/A within 2 hours of application to incorporate product into root-zone: Over-the-row band spray in Annual or Perennial crops Soil-surface spray application in a minimum of 20 gallons of water/A followed by 0.25” of rainfall or irrigation II-11 water/A within 2 hours of application to incorporate product into root-zone: Raw band spray with a width equal to the anticipated fruiting bed in Perennial crops II-12 Soil Surface spray Directed to the root and crown area with high volume of spray (20 gal) II-13 Side-dress no later than 45 days after-planting High-volume basal drench to slightly moist soil surrounding the tree trunk. Applied in sufficient volume to II-14 penetrate the soil to a depth of 18 – 24” (for Termite control) Low-pressure chemigation or Soil surface band spray with irrigation to ensure complete coverage of the root II-15 system (for Nematode suppression) II-16 Emitter or spot application in a minimum of 4 fluid ounces of mixture per emitter site Chemigation or the French plow technique followed immediately by sufficient irrigation to move the product II-17 into the entire root-zone of the plant (for Nematode suppression) 1 DSGN= Designation

Table D-12 contains a summary of the labeled soil application method(s) that may be used in modeling each of the imidacloprid use patterns.

Table D-12. Assignment of the Soil Application Methods to Varied Imidacloprid Use Patterns Labeled Application Method for Soil Use Pattern: (Crop group/subgroup) Category I Category II Artichoke (Globe) I-1; I-2 II-5 Banana & Plantain None II-5 Brassica (Cole) Vegetables (05) I-1, I-5, I-6, I-8 II-5 Bulb Vegetables (03-07) I-1, I-5, I-8 II-5 Bushberry (13-07-C) None II-5; II-9 Caneberry (13-07-A) None II-5, II-6 Citrus (10) None II-3; II-7; II-8; II-10, II-14; II-15 Coffee None II-2; II-3, II-5 Cotton I-1, I-5 II-5 Cranberry (13-07-B) None II-6 Cucurbit Vegetables (09) I-1, I-5, I-6, I-8 II-5 Fruiting Vegetables (08) + Okra I-1, I-5, I-6, I-8 II-5

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Labeled Application Method for Soil Use Pattern: (Crop group/subgroup) Category I Category II Grape (13-07D/F) I-8 II-2; II-5, II-17 Herbs & spices (19-A) I-2, I-7, I-8 II-5 Hops I-1, I-8 II-2, II-5 Leafy Green vegetables (04-A) I-1, I-5, I-6, I-8 II-5 Leafy Petiole vegetables (04-B) I-1, I-5, I-6, I-8 II-5 Legume Vegetables (06), except Soybeans I-1, I-5, I-6, I-8 II-5 Peanut I-1 II-5 Pome Fruits (11) None II-5 Pomegranate None II-5 Potatoes (1C) I-1, I-5, I-6 II-1, II-5 Root Vegetables (01-B), except Sugarbeet I-1, I-5, I-7 II-5 Stone Fruits (12) None II-5 Strawberry: Annual & Perennial (13-07G) None II-6, II-10, II-11, II-16 Strawberry: Perennial @ Post Harvest (13-07G) I-9 II-6, II-11 Sugarbeet (1A) I-4 None Tobacco I-1 II-1, II-5 Tree Nuts (14) None II-2, II-5, II-14, II-16 Tropical Fruits (23 and 24) None II-5 Tuberous and Corm Vegetables (01-C) I-3, I-7 II-13 Watercress (4A) I-1, I-5, I-6, I-8 II-5

As shown in Table D-11 and Table D-12, labels for imidacloprid stress that the objective of the application procedure is to place or drive the pesticide product into the root zone. Having the pesticide in the root zone will make it available for upward xylem translocation into the plant foliage. To achieve this, labels suggest using high drench volumes, application just before expected rain, or irrigation just after application among many others.

For granular formulations, ground equipment is usually used to deliver the pesticide that is ultimately placed on the soil surface below the crop if the label does not call for its incorporation.

In PWC modeling, an application method is to be selected from seven methods. For imidacloprid, one of the following four methods may be selected to represent the foliar and the soil application methods detailed, above. The four methods are: “below crop”, “above crop”, “uniform below” and “@depth”. The “uniform below” and “@depth” application methods require depth (in cm) to be specified. Based on the application methods described above, a summary table was established containing the required inputs; Table D-13). Each of the application inputs was selected based on the expected depth distribution of the chemical in the soil. In some cases, depth of the pesticide placement is given in the label and in most cases the depth is specified as the depth of seeding or transplanting or the placement depth achieved by drenching or watering-in to the root zone. Seeding and Transplanting depths were obtained from the literature. However, the possible placement depth for drenching and watering-in may not achieve the objective of reaching the root zone depending on many factors such as soil permeability and solubility/mobility of the pesticide. Therefore, the depth for drenching and watering-in was arbitrarily assigned based on the crop and characteristics of the soil of the scenario representing it. Due to the possibility that placement of the pesticide into the root zone may not be achieved by drenching

216 and or chemigation, effects of the arbitrarily assigned depth for the “@ depth” and “uniform below” application methods on modeled EECs, will be discussed later in this assessment.

Table D-13. PWC Application Methods and Associated Depths Used in Modeling PWC Application Method Designation1 Depth Drift (Ground) Method I-1 Seeding depth I-2 Seed or Transplanting depth "@ depth" I-7 2.5 cm NO I-9 Transplanting depth; and II-2 Root zone depth I-3; I-4; I-5 Seeding depth I-6 7.6 cm "@ depth" YES II-1 7.6 cm II-13 Root zone depth Seeding or Transplanting I-8 depth II-3; II-4 Root zone depth “Uniform below” II-5 Root zone depth NO II-6; II-7; II-15 Root zone depth II-14 46 cm II-16; II-17 Root zone depth “Uniform below” II-8; II-9; II-10; II-11; II-12 Root zone depth YES 1 For method designation, description and use patterns refer to Table D-10, D-11, and D-12.

Finally, the PWC application method used for foliar application is “above crop” when the pesticide is applied directly onto foliage, and when the pesticide is directly applied into the surface soil (e.g., for granular formulations), the “below crop” application method is used.

Representative Scenarios

Table D-14. Imidacloprid Use Patterns and their Representative Scenario(s) Use Pattern (C-CG-Sub G)1 Representative Scenario(s) Artichoke, Globe CARowCropRLF_V2 for Artichokes CAAvocadoRLF_V2; FLavocadoSTD; Banana and Plantain CAcitrus_WirrigSTD; FLcitrusSTD Brassica (cole) Vegetables (05): Whole Group, Broccoli & CAColeCropRLF_V2; FLcabbageSTD Mustard CAGarlicRLF_V3; CAonion_WirrigSTD; Bulb Vegetables (3-07): Whole Group, Leek and Onion GAOnion_WirrigSTD; WAonionsNMC Bushberry (13-7-B) and Caneberry (13-A) ORberriesOP Citrus (10) CAcitrus_WirrigSTD; FLcitrusSTD; STXgrapefruitNMC Coffee PRcoffeeSTD CAcotton_WirrigSTD; MScottonSTD; NCcottonSTD; Cotton STXcottonNMC; TXcottonOP

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Use Pattern (C-CG-Sub G)1 Representative Scenario(s) CAMelonsRLF_V2; FLcucumberSTD; MImelonStd; Cucurbit Vegetables (09) MOmelonStd; NJmelonStd; STXmelonNMC for pumpkins Fruiting Vegetables (08): Peppers FLpeppersSTD CAtomato_WirrigSTD; FLtomatoSTD_V2; Fruiting Vegetables (08): Others PAtomatoSTD CAgrapes_WirrigSTD; CAWineGrapesRLF_V2; Grape (13-07D/F NYGrapesSTD Herbs & Spices (19-A): Whole Group and Borage ORmintSTD Hops ORhopsSTD Leafy Green Vegetables (04-A) CAlettuceSTD Leafy Petiole vegetables (04-B) CARowCropRLF_V2 for celery Legume Vegetables (6-C), except Soybeans: Whole group & ILbeansNMC; MIbeansSTD; ORsnbeansSTD Beans-Peas CAnurserySTD_V2; FLnurserySTD_V2; Nurseries MInurserySTD_V2; NJnurserySTD_V2; ORnurserySTD_V2; TNnurserySTD_V2 Peanuts NCpeanutSTD NCappleSTD; ORappleSTD; PAappleSTD_V2; Pome Fruits (11) WAorchardsNMC Pomegranate CAfruit_WirrigSTD CAPotatoRLF_V2; FLpotatoNMC; Potato (1C) IDNpotato_WirrigSTD; MEpotatoSTD Root Vegetables (01-B) except Sugarbeet: Whole Group and FLcarrotSTD Carrots Seed Treatment: Canola/Rape NDcanolaSTD CAWheatRLF_V2; NDwheatSTD; ORwheatOP; Seed Treatment: Flax, Crambe TXwheatOP Seed Treatment: Sorghum KSsorghumSTD; TXsorghumOP Soybeans (06) MSsoybeanSTD Stone Fruits (12): Apricot, Nectarine & Peach CAfruit_WirrigSTD; GAPeachesSTD Stone Fruits (12): Cherries, Plums, Plumcot, Prune CAfruit_WirrigSTD; MICherriesSTD CAStrawberry-noplasticRLF_V2; Strawberry (13-07G) FLstrawberry_WirrigSTD Sugarbeet (1A) CAsugarbeet_WirrigOP; MNsugarbeetSTD Tobacco NCtobaccoSTD Tree nuts (14) CAalmond_WirrigSTD; GAPecansSTD; ORfilbertsSTD Tropical Fruits CAAvocadoRLF_V2; FLavocadoSTD Tuberous Corm Vegetables (01-C) NCSweetPotatoSTD Turf CATurfRLF; FLturfSTD; PAturfSTD Poplar/cottonwood CAForestryRLF; PAappleSTD_V2; FLcitrusSTD X-mass Trees ORXmasTreeSTD Watercress (4A) PFAM

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