Overview of Antimony Trioxide (ATO) Workplan Risk Assessment

1. Overview of Antimony Trioxide (ATO) Workplan Risk Assessment Oxide Metal Antimony Trioxide (ATO) CASRN 1309-64-4 Sharon Oxendine Office of Pollution Prevention and Toxics November 13, 2013

2. Presentation Overview This presentation will provide: • Background on ATO • Key science issues Please comment on the clarity, strengths and weaknesses of the assessment and how it specifically may be improved. Office of Pollution Prevention and Toxics2

3. Basis for Selection • Exposure • -23,000 metric tons imported in 2012 - widespread use in consumer products • Human Health Effects • - inhalation toxicity • -possible carcinogen • Environmental Releases • - persistence • - bioaccumulation Office of Pollution Prevention and Toxics3

4. Scope of the Assessment • Evaluated ecological risks associated with ATO use in halogenated flame retardants ×Human health risks were not the focus of this assessment Office of Pollution Prevention and Toxics 4

5. ATO Antimony Compounds Conceptual Model for ATO Risk Assessment focuses on ecological risks resulting from industrial releases to water

6. Chemistry, Fate and Transport • Please comment on the use of chemistry, fate and transport • information to evaluate bioavailability in environmental media. Office of Pollution Prevention and Toxics 6

7. Hazard Characterization • Please comment on the use of toxicity data for antimony trichloride to characterize aquatic toxicity. Office of Pollution Prevention and Toxics 7

8. Criteria for Selection of TRI Facilities  NAICS codes  Reported water releases  Availability of “7Q10” streamflow data Office of Pollution Prevention and Toxics 8

9. Monitoring: USGS-NWIS & EPA STORET 9

10. Monitoring Data: Office of Pollution Prevention and Toxics11

11. Can we generalize from this data to other regions? • Please comment on the use of these data sets to characterize ecological exposures. Do they adequately reflect conditions at other locations in the US? • Are there other major sources of environmental monitoring data (or other pertinent information) that EPA should consider in the exposure assessment? If so, please provide the necessary citations and/or data for inclusion in the revised document. • Are there concerns or limitations in these data sets that may impact their utility for risk assessment? Office of Pollution Prevention and Toxics 11

12. Use of the category ‘antimony compounds’ as a surrogate to estimate ATO releases • Are there other data sources and/or approaches that EPA should consider for estimating environmental releases? If so, please provide citations or data for consideration in further revision of the draft assessment. Office of Pollution Prevention and Toxics 12

13. Exposure and Fate Assessment Screening Tool (Version 2) model estimates of surface water concentrations • Two release scenarios (assuming total yearly TRI releases occurred over a period of 24- or 250 days/year) were used to provide a range of predicted water concentrations for comparison with hazard benchmarks (concentrations of concern). Please comment on the EFAST2 modeling approach used to assess aquatic risks. Office of Pollution Prevention and Toxics 13

14. Risk Quotient Approach • Environmental concentrations reflect measured or estimated values • COCs were calculated from the most sensitive effect levels • Risks indicated when the environmental concentration exceeds COC • (i.e., RQ > 1) Environmental Concentration RQ = COC Office of Pollution Prevention and Toxics 14

15. Validity of Assumptions • Please comment on the implicit assumption that antimony levels measured in environmental media reflect inputs from various types of antimony compounds and end use applications and how this could impact risk estimates. • Findings reported in this assessment are thought to represent • conservative estimates of risk. Please comment on the validity of • this statement and the likelihood that actual risks have been over • (or under) estimated. Office of Pollution Prevention and Toxics 15

16. Risk Summary Office of Pollution Prevention and Toxics 16

17. Monitoring Results Selected TRI facilities ( ) are shown as a point of reference Office of Pollution Prevention and Toxics 20

18. Conclusion Minimal risks are expected for ecological organisms: • The available environmental monitoring data reflect input from various sources and types of antimony compounds. • Use of ‘antimony compounds’ as a surrogate for ATO and model estimates based on the assumption of yearly TRI releases occurring over a 24-day period provide conservative estimates of exposure potential. • Use of highly sensitive ecological species showed few instances where measured or predicted concentrations in environmental media exceeded the COC for water-, or sediment-dwelling organisms. Office of Pollution Prevention and Toxics 18

19. Uncertainty and Data Limitations Risk findings are constrained by a number of uncertainties regarding data quality (e.g., adequacy of TRI reporting, model assumptions, and environmental monitoring data). Environmental fate and transport are influenced by site-specific conditions that can impact bioavailability. Since these parameters vary, it is difficult to extrapolate to other geographic regions within the US. There is little or no overlap between the geographic locations of selected TRI facilities and the available monitoring data, therefore a direct linkage to ATO use as a flame retardant synergist is not possible. Office of Pollution Prevention and Toxics 19

20. Key Technical Issues Raised in Public Comments • Exposure • -Use of conservative assumptions in exposure assessment • -Rationale for selection of end-use scenario • Hazard • -Lack of transparency in hazard characterization • -Unclear criteria for study selection • Risk • -Risk quotient versus margin of exposure • -Use of phrases such as “minimal concern” Office of Pollution Prevention and Toxics 20

21. Acknowledgements Office of Pollution Prevention and Toxics 21 Office of Chemical Safety and Pollution Prevention

22. Thank you!

23. Aquatic Toxicity Data Office of Pollution Prevention and Toxics 23

24. Sediment Toxicity Data Office of Pollution Prevention and Toxics 24

25. Soil Toxicity Data Office of Pollution Prevention and Toxics 25

26. U.S. Geological Survey Open-File Report http://mrdata.usgs.gov/geochem/doc/home.htm 26

27. USGS National Stream Quality Accounting Network (1996-2000) http://pubs.usgs.gov/wri/wri014255/results/detect/pd01095.png 27

28. ANTIMONY STATISTICS1 (Metric tons of antimony content) United States: 2008 2009 2010 2011 2012 Mine production -- -- -- -- -- Smelter production: Primary W WWWW Secondary 3,180 3,020 3,520 3,230 3,730 Exports: Metal, alloys, waste and scrap (gross weight) 366 385 427 581 847 Antimony oxide2 1,830 1,710 2,120 3,590 3,870 Imports for consumption 29,000 20,200 26,200 23,500 22,600 Reported industrial consumption, primary antimony 8,140 6,770 8,860 10,200 10200 Price, average3 (cents per pound) 279.5 235.6 401.2 650.3 564.5 Global mine production 185,000r 154,000 178,000r 183,000r 174,000e e Estimated. r Revised. W Withheld to avoid disclosing company proprietary data, -- Zero. 1Data are rounded to no more than three significant digits, except prices. 2Antimony content data were calculated by the U.S. Geological Survey. 3New York dealer price for 99.5% to 99.6% metal, cost, insurance, freight U.S. ports. (USGS, 2012) Office of Pollution Prevention and Toxics 28