United States EPA Document # 740‐Z1‐4001 Environmental Protection August 2014 Agency Office of Chemical Safety and Pollution Prevention ______________________________________________________________________________ TSCA Work Plan Chemical Risk Assessment Antimony Trioxide CASRN: 1309‐64‐4 August 2014 TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................... 2 LIST OF TABLES ........................................................................................................................ 4 LIST OF APPENDIX TABLES ....................................................................................................... 4 LIST OF FIGURES ...................................................................................................................... 5 AUTHORS / CONTRIBUTORS / ACKNOWLEDGEMENTS / REVIEWERS ....................................... 6 GLOSSARY OF TERMS AND ABBREVIATIONS ............................................................................ 8 EXECUTIVE SUMMARY ........................................................................................................... 10 1 BACKGROUND AND SCOPE ............................................................................................. 12 1.1 INTRODUCTION .......................................................................................................................................... 12 1.2 PROBLEM FORMULATION .......................................................................................................................... 13 1.2.1 ATO Uses ................................................................................................................................................ 13 1.2.2 Regulation of ATO .................................................................................................................................. 14 1.2.3 Human Exposure Potential ..................................................................................................................... 14 1.2.4 Ecological Exposure Potential ................................................................................................................. 15 1.2.5 Ecological Hazard Assessment ............................................................................................................... 15 1.3 CONCEPTUAL MODEL FOR ENVIRONMENTAL ASSESSMENT OF ATO ......................................................... 16 1.4 ANALYSIS PLAN FOR ENVIRONMENTAL ASSESSMENT ................................................................................ 19 2 SOURCES AND ENVIRONMENTAL FATE ........................................................................... 20 2.1 INTRODUCTION .......................................................................................................................................... 20 2.1.1 Physical and Chemical Properties ........................................................................................................... 20 2.2 PRODUCTION AND USES ............................................................................................................................. 21 2.3 ENVIRONMENTAL FATE .............................................................................................................................. 23 2.3.1 Environmental Persistence .................................................................................................................... 23 2.3.1.1 Fate in Water .................................................................................................................................................... 23 2.3.1.2 Fate in Sediment ............................................................................................................................................... 24 2.3.1.3 Fate in Soil ........................................................................................................................................................ 25 2.3.1.4 Fate in Air ......................................................................................................................................................... 26 2.3.2 Environmental Bioavailability, Transformation and Bioaccumulation .............................................. 27 2.3.2.1 Bioavailability ................................................................................................................................................... 27 2.3.2.2 Transformation ................................................................................................................................................. 29 2.3.2.3 Bioaccumulation ............................................................................................................................................... 30 2.3.3 Conclusion of Environmental Fate ........................................................................................................ 31 3 ENVIRONMENTAL ASSESSMENT ..................................................................................... 32 3.1 INTRODUCTION .......................................................................................................................................... 32 3.1.1 Environmental Exposure Assessment ..................................................................................................... 32 3.1.2 Toxics Release Inventory......................................................................................................................... 32 3.1.3 Measured Concentrations in the Environment ..................................................................................... 36 3.1.3.1 Compilation of Environmental Monitoring Data from USGS‐NWIS Database .................................................. 36 3.1.3.2 Compilation of Environmental Monitoring Data from the STORET Database .................................................. 37 3.1.3.3 Location of Monitoring Sites Relative to TRI Facilities ...................................................................................... 39 Page 2 of 87 3.1.4 Estimated Environmental Releases ....................................................................................................... 39 3.1.4.1 EFAST Modeling ................................................................................................................................................ 39 3.1.4.2 Criteria for Selection of TRI Facilities ................................................................................................................ 40 3.1.4.3 Release Scenarios used for Exposure Characterization .................................................................................... 40 3.2 ECOLOGICAL HAZARD ASSESSMENT ........................................................................................................... 42 3.2.1 Acute Toxicity to Aquatic Organisms .................................................................................................... 43 3.2.2 Chronic Toxicity to Aquatic Organisms ................................................................................................. 45 3.2.3 Toxicity to Sediment‐Dwelling Organisms .............................................................................................. 47 3.2.4 Chronic Toxicity to Terrestrial Organisms ............................................................................................... 48 3.2.5 Conclusions of Environmental Hazard Assessment .............................................................................. 50 3.3 ENVIRONMENTAL RISK CHARACTERIZATION ............................................................................................. 50 3.3.1 Summary of TRI Modeling Results ........................................................................................................ 51 3.3.2 Summary of Environmental Monitoring Data ...................................................................................... 54 3.3.3 Conclusions of Risk Characterization .................................................................................................... 54 3.3.4 Uncertainty and Data Limitations ........................................................................................................ 55 3.3.4.1 Limitations of the Exposure and Release Data ................................................................................................. 55 3.3.4.2 E‐FAST2 Model Uncertainties ........................................................................................................................... 56 3.3.4.3 Limitations of the Hazard Data ......................................................................................................................... 56 3.4 CONCLUSIONS ............................................................................................................................................ 57 REFERENCES .......................................................................................................................... 58 APPENDICES .......................................................................................................................... 70 Appendix A HUMAN HEALTH HAZARD SUMMARY .............................................................. 71 A‐1 TOXICOKINETICS ....................................................................................................................................... 71 A‐2 ACUTE TOXICITY .......................................................................................................................................