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Sodium Cyanide. Human Health Risk Assessment in Support of Registration Review

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Sodium Cyanide. Human Health Risk Assessment in Support of Registration Review UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460 OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM Date: September 18, 2018 SUBJECT: Sodium Cyanide. Human Health Risk Assessment in Support of Registration Review. PC Code: 045801 & 074002 DP Barcode: D447111 Decision No.: 541080 Registration No.: 6704-75, CA840006, etc. Petition No.: NA Regulatory Action: Registration Review Risk Assessment Type: Single Chemical, Aggregate Case No.: 3073 TXR No.: NA CAS No.: 74-90-8 & 143-33-9 MRID No.: NA 40 CFR: §180.130 FROM: Brian Van Deusen, Risk Assessor Janet Camp, Risk Assessor Thurston Morton, Dietary Assessor/Residue Chemist Minerva Mercado, Toxicologist Risk Assessment Branch 4 (RAB4) Health Effects Division (HED, 7509P) THROUGH: Donald Wilbur, Branch Chief Risk Assessment Branch 4 (RAB4) Health Effects Division (HED) (7509P) TO: Leigh Rimmer, Chemical Review Manager Nicole Zinn, Team Leader Risk Management and Implementation Branch 2 (RMIB2) Pesticide Re-evaluation Division (7508P) Office of Pesticide Programs As part of Registration Review, PRD has requested that HED evaluate the hazard and exposure data and estimate the risks to human health that will result from the currently registered uses of sodium cyanide. The most recent human health risk assessment for sodium cyanide was performed in 2006 (B. Daiss, 7/10/2006, D318015). A Human Health Assessment Scoping Document in Support of Registration Review (B. Daiss, 9/8/2010, D373692) for sodium cyanide was completed in 2010. No risk assessment updates other than an updated acute dietary exposure assessment have been made in conjunction with registration review. This memorandum is an updated review of the previous risk assessment and serves as HED’s draft human health risk assessment for the registered uses of sodium cyanide. Sodium Cyanide Human Health Risk Assessment DP No. 447111 Table of Contents Use Profile and Risk Assessment Conclusions .................................................................... 3 Data Deficiencies .......................................................................................................... 3 Tolerance Considerations ............................................................................................. 4 Label Recommendations .............................................................................................. 4 Chemical Identity ......................................................................................................... 4 Hazard Characterization and Dose-Response Assessment .................................................. 5 Toxicology Studies Available for Analysis .................................................................. 5 Toxicological Effects .................................................................................................... 6 Safety Factor for Infants and Children (FQPA Safety Factor) ..................................... 8 Completeness of the Toxicology Database ............................................................... 8 Evidence of Neurotoxicity ........................................................................................ 8 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal ........... 8 Toxicity Endpoint and Point of Departure (POD) Selections ...................................... 9 Cancer Classification and Risk Assessment Recommendation .............................. 10 Dietary, Residential and Aggregate Exposure/Risk Characterization ............................... 10 Dietary Exposure/Risk Characterization .................................................................... 10 Residential and Bystander Exposure .......................................................................... 11 Aggregate Exposure ................................................................................................... 11 Occupational Handler and Post-Application Exposure/Risk Characterization ................. 11 Incident and Epidemiological Data Review ...................................................................... 13 References .......................................................................................................................... 13 Appendix A. Toxicology Profile and Executive Summaries ....................................................... 17 A.1 Toxicology Data Requirements .................................................................................. 17 A.2 Toxicity Profiles ......................................................................................................... 18 A.3 Literature Search for Sodium Cyanide ....................................................................... 23 Appendix B. International Residue Limits .................................................................................. 24 Page 2 of 24 Sodium Cyanide Human Health Risk Assessment DP No. 447111 Use Profile and Risk Assessment Conclusions Sodium cyanide is registered for use as a predacide and as an insecticide. As a predacide, it is used as an encapsulated single dose poison to control animals that are vectors of communicable disease or animals that prey upon livestock or threatened or endangered species. Individual capsules are loaded into an ejector device which is anchored to the ground. The capsule holder is treated with a scent used to attract predators to the unit. When an animal tugs at the capsule holder, a spring-driven plunger ejects the sodium cyanide capsule into its mouth. This product is limited to use only by trained and certified applicators under the direct supervision of a government agency. Occupational handler and post-application exposures for the use of sodium cyanide in these bait products are considered negligible based on use information, label restrictions, and the sodium cyanide being sealed within the ejector devices and placed in remote locations which effectively limits exposure. As an insecticide, sodium cyanide is used as a source of hydrogen cyanide gas for quarantine fumigation of surface pests on citrus. There are two special local needs (SLN) food/feed use registrations for sodium cyanide as a fumigant in Arizona and California. However, active fumigation of citrus with hydrogen cyanide is limited to a single facility in California to control red scale on fresh market citrus bound for Arizona. The SLN end-use product is a granular formulation containing 98% sodium cyanide as the active ingredient. It is applied by professional applicators only. There are no products available for residential application. Dermal exposures are not expected based on the limited use pattern and were therefore not assessed. There is the potential for inhalation exposure to workers to hydrogen cyanide from its use in post-harvest fumigation of citrus contained in closed transport trailers. Sodium cyanide is a restricted use pesticide that results in limited exposure to handlers. An acute dietary assessment resulted in no risks of concern. There are no registered residential uses so an aggregate exposure assessment is not needed. Even though sodium cyanide is restricted use and personal protective equipment (PPE) and extensive restrictions are required on the SLN label in order to decrease the likelihood of exposure, if inhalation exposures of hydrogen cyanide occur, there will be adverse effects. Based on potential occupational handler and post-application inhalation exposures to hydrogen cyanide from the post-harvest use on citrus, it may pose a human-health risk of concern. However, based on a review of the limited use pattern in California, the lack of incidents reported, and the requirement of handlers to wear personal hydrogen cyanide detector monitors, EPA concludes that the potential for exposure and risks is low. Data Deficiencies Residue chemistry deficiencies at the time of the RED are now satisfied except for the submittal of analytical standards. Analytical standards are not currently available in the EPA National Pesticide Standards Repository. Analytical reference standards must be supplied and replenished as necessary, as long as tolerances remain published in 40 CFR §180.130. Page 3 of 24 Sodium Cyanide Human Health Risk Assessment DP No. 447111 Tolerance Considerations In 2009 HED issued guidance on tolerance expressions (S. Knizner, 2009). We now conclude the tolerance expression should be revised as follows: Tolerances are established for residues of sodium cyanide, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels specified below is to be determined by measuring only hydrogen cyanide in or on the commodity. Table 1.2.1. Summary of Hydrogen Cyanide Established and Recommended Tolerances for Registration Review. (a) General. Tolerances are established for residues of sodium cyanide, including its metabolites and degradates, in or on the commodities in the table below. Compliance with the tolerance levels specified below is to be determined by measuring only hydrogen cyanide in or on the commodity: Established Revised Comments Commodity/Correct Commodity Definition Tolerance Tolerance (ppm) (ppm) Fruit, citrus, group 10-10 50 Commodity definition revision Fruit, citrus 50 Remove The Codex Alimentarius and Canada have not established maximum residue limits (MRLs) for citrus fruit. Therefore, international harmonization is not an issue at this time. Label Recommendations There are no residue chemistry related label recommendations. Chemical Identity Table 1.4.1. Test Compound
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