SERA TR 056-08-02b Scoping/Screening Level Risk Assessment on Clethodim: Final Report Submitted to: Dr. Harold Thistle USDA Forest Service Forest Health Technology Enterprise Team 180 Canfield St. Morgantown, WV 26505 Email: [email protected] USDA Forest Service Contract: AG-3187-C-12-0009 USDA Forest Service Order Number: AG-3187-D-14-0107 SERA Internal Task No. 56-08 Submitted by: Patrick R. Durkin Syracuse Environmental Research Associates, Inc. 8125 Solomon Seal Manlius, New York 13104 E-Mail: [email protected] Home Page: www.sera-inc.com October 30, 2014 Preface This report is based on a revision to SERA TR-056-05-01-02a, Scoping/Screening Level Risk Assessment on Clethodim, dated March 28, 2014. This document is updated to reflect the recent documents released by the U.S. EPA’s Office of Pesticide Programs’ registration review of clethodim (U.S. EPA/OPP/EFED 2013a, 2014a; U.S. EPA/OPP/HED 2013a,b, 2014a) as well as peer review comments. This document is compliant with Section 508 of the Rehabilitation Act of 1973 as amended by the Workforce Investment Act of 1998. The compliance report is attached to the PDF version of this risk assessment. Table of Contents LIST OF TABLES ........................................................................................................................ vii LIST OF FIGURES ...................................................................................................................... vii LIST OF APPENDICES .............................................................................................................. viii LIST OF ATTACHMENTS ........................................................................................................ viii ACRONYMS, ABBREVIATIONS, AND SYMBOLS ................................................................ ix CONVERSION OF SCIENTIFIC NOTATION ......................................................................... xiii EXECUTIVE SUMMARY ......................................................................................................... xiv 1. INTRODUCTION ...................................................................................................................... 1 1.1. Chemical Specific Information ............................................................................................ 1 1.2. General Information ............................................................................................................. 3 2. PROGRAMS DESCRIPTION ................................................................................................... 6 2.1. Overview .............................................................................................................................. 6 2.2. Chemical Description and Commercial Formulations ......................................................... 7 2.3. Application Methods .......................................................................................................... 10 2.4. Mixing and Application Rates ........................................................................................... 11 2.5. Use Statistics ...................................................................................................................... 12 3. HUMAN HEALTH .................................................................................................................. 14 3.1. HAZARD IDENTIFICATION ........................................................................................ 14 3.1.1. Overview ..................................................................................................................... 14 3.1.2. Mechanism of Action .................................................................................................. 14 3.1.3. Pharmacokinetics and Metabolism ............................................................................. 15 3.1.3.1. General Considerations ........................................................................................ 15 3.1.3.2. Absorption............................................................................................................ 17 3.1.3.2.1. First-Order Dermal Absorption..................................................................... 17 3.1.3.2.2. Zero-Order Dermal Absorption .................................................................... 19 3.1.3.3. Excretion .............................................................................................................. 19 3.1.4. Acute Oral Toxicity .................................................................................................... 20 3.1.5. Subchronic or Chronic Systemic Toxic Effects .......................................................... 22 ii 3.1.6. Effects on Nervous System ......................................................................................... 23 3.1.7. Effects on Immune System ......................................................................................... 24 3.1.8. Effects on Endocrine System ...................................................................................... 25 3.1.9. Reproductive and Developmental Effects .................................................................. 25 3.1.9.1. Developmental Studies ........................................................................................ 25 3.1.9.2. Reproduction Studies ........................................................................................... 26 3.1.10. Carcinogenicity and Mutagenicity ............................................................................ 27 3.1.11. Irritation and Sensitization (Effects on the Skin and Eyes) ...................................... 27 3.1.11.1. Skin Irritation ..................................................................................................... 28 3.1.11.2. Skin Sensitization............................................................................................... 28 3.1.11.3. Ocular Effects .................................................................................................... 29 3.1.12. Systemic Toxic Effects from Dermal Exposure ....................................................... 29 3.1.12.1. Acute Studies ..................................................................................................... 29 3.1.12.2. Repeated Dose Studies ....................................................................................... 30 3.1.13. Inhalation Exposure .................................................................................................. 30 3.1.14. Adjuvants and Other Ingredients .............................................................................. 31 3.1.14.2. Other Ingredients ............................................................................................... 31 3.1.14.2. Adjuvants ........................................................................................................... 33 3.1.15. Impurities and Metabolites ....................................................................................... 34 3.1.15.1. Metabolites ......................................................................................................... 34 3.1.15.2. Impurities ........................................................................................................... 34 3.1.16. Toxicological Interactions ........................................................................................ 35 3.2. EXPOSURE ASSESSMENT .......................................................................................... 36 3.2.1. Overview ..................................................................................................................... 36 3.2.2. Workers ....................................................................................................................... 36 3.2.2.1. General Exposures ............................................................................................... 37 3.2.2.2. Accidental Exposures........................................................................................... 39 3.2.3. General Public ........................................................................................................... 40 3.2.3.1. General Considerations ........................................................................................ 40 3.2.3.1.1. Likelihood and Magnitude of Exposure ....................................................... 40 3.2.3.1.2. Summary of Assessments ............................................................................. 41 3.2.3.2. Direct Spray ......................................................................................................... 42 3.2.3.3. Dermal Exposure from Contaminated Vegetation ............................................... 43 3.2.3.4. Contaminated Water ............................................................................................ 43 3.2.3.4.1. Accidental Spill ............................................................................................. 43 3.2.3.4.2. Accidental Direct Spray/Drift to a Pond or Stream ...................................... 44 3.2.3.4.3. GLEAMS-Driver Modeling .......................................................................... 44 iii 3.2.3.4.4. Other Modeling Efforts ................................................................................. 45 3.2.3.4.5. Monitoring Data ............................................................................................ 46 3.2.3.4.6. Concentrations