Presentation on theme: "Oxide Metal Overview of Antimony Trioxide (ATO) Workplan Risk Assessment Sharon Oxendine Office of Pollution Prevention and Toxics November 13, 2013 Antimony."— Presentation transcript:
Oxide Metal Overview of Antimony Trioxide (ATO) Workplan Risk Assessment Sharon Oxendine Office of Pollution Prevention and Toxics November 13, 2013 Antimony Trioxide (ATO) CASRN 1309-64-4
Presentation Overview This presentation will provide: Background on ATO Key science issues Office of Pollution Prevention and Toxics 2 Please comment on the clarity, strengths and weaknesses of the assessment and how it specifically may be improved.
Basis for Selection Office of Pollution Prevention and Toxics 3 * Human Health Effects - inhalation toxicity - possible carcinogen * Exposure - 23,000 metric tons imported in 2012 - widespread use in consumer products * Environmental Releases - persistence - bioaccumulation
Scope of the Assessment Evaluated ecological risks associated with ATO use in halogenated flame retardants Office of Pollution Prevention and Toxics 4 × Human health risks were not the focus of this assessment
ATO Antimony Compounds Conceptual Model for ATO Risk Assessment focuses on ecological risks resulting from industrial releases to water
Office of Pollution Prevention and Toxics 6 Chemistry, Fate and Transport Please comment on the use of chemistry, fate and transport information to evaluate bioavailability in environmental media.
Hazard Characterization Please comment on the use of toxicity data for antimony trichloride to characterize aquatic toxicity. Office of Pollution Prevention and Toxics 7
Criteria for Selection of TRI Facilities Office of Pollution Prevention and Toxics 8 NAICS codes Reported water releases Availability of “7Q10” streamflow data
Monitoring Data: Office of Pollution Prevention and Toxics 11
Can we generalize from this data to other regions? Office of Pollution Prevention and Toxics 11 Are there concerns or limitations in these data sets that may impact their utility for risk assessment? 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. Please comment on the use of these data sets to characterize ecological exposures. Do they adequately reflect conditions at other locations in the US?
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
Office of Pollution Prevention and Toxics 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.
Risk Quotient Approach RQ = Environmental Concentration COC Environmental concentrations reflect measured or estimated values Office of Pollution Prevention and Toxics 14 COCs were calculated from the most sensitive effect levels Risks indicated when the environmental concentration exceeds COC (i.e., RQ > 1)
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. 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. Validity of Assumptions Office of Pollution Prevention and Toxics 15
Risk Summary Office of Pollution Prevention and Toxics 16 Media TypeOrganismEndpointCOC Monitoring Data Modeled Data Water C. viridissima96-hour LC 50 = 1.77 mg/L354 ppb (acute)No exceedanceOne exceedance P. Promelas30-day GMATC = 1.62 mg/L162 ppb (chronic) ~ 0.2% above chronic COC No exceedances Sediment L. variegatus or C. riparius 28-d NOEC = 112 mg Sb/kg dw 112 mg Sb/kg dw (acute) No exceedances- 11.2 mg Sb/kg dw (chronic) ~ 0.7% above chronic COC -
Monitoring Results Office of Pollution Prevention and Toxics 20 Selected TRI facilities ( ) are shown as a point of reference
Conclusion Minimal risks are expected for ecological organisms: Office of Pollution Prevention and Toxics 18 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. 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.
Uncertainty and Data Limitations Office of Pollution Prevention and Toxics 19 Risk findings are constrained by a number of uncertainties regarding data quality (e.g., adequacy of TRI reporting, model assumptions, and environmental monitoring data). 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. 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.
Key Technical Issues Raised in Public Comments Office of Pollution Prevention and Toxics 20 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” Exposure - Use of conservative assumptions in exposure assessment - Rationale for selection of end-use scenario
Acknowledgements Office of Chemical Safety and Pollution Prevention Office of Pollution Prevention and Toxics 21 Kay AustinJay Jon Stanley BaroneSharon Oxendine Cathy FehrenbacherWen-Hsiung Lee Nhan NguyenTim Lehman Louis ScaranoSara Pollack Christina CinalliEmma Lavoie Rick FehirKirsten Hesla Contract Support Portions of this document were developed with support from SRC, Eastern Research Group and Versar.
Sediment Toxicity Data Office of Pollution Prevention and Toxics 24 Test OrganismSpeciesEndpoint Antimony Compound ValueReference AmphipodHyalella aztecaSurvival/growth/ reproduction SbCl 3 NOEC = 87 mg Sb/kg ww (124 mg Sb/kg dw) Heijerick and Vangheluwe (2003aHeijerick and Vangheluwe (2003a) OligochaeteLumbriculus variegatus Survival/growth/ reproduction SbCl 3 NOEC = 78 mg Sb/kg ww (112 mg Sb/kg dw) Heijerick and Vangheluwe (2005aHeijerick and Vangheluwe (2005a) Midge larvaeChironomus riparius Survival/growth/ reproduction SbCl 3 NOEC = 78 mg Sb/kg ww (112 mg Sb/kg dw) Heijerick and Vangheluwe (2005bHeijerick and Vangheluwe (2005b)
Test OrganismSpeciesEndpoint Antimony Compound ValueReference SpringtailFolsomia candidaReproductionSb 2 O 3 NOEC reproduction = 999 mg Sb/kg dw LOEC reproduction = 2,930 mg Sb/kg dw Moser (2007Moser (2007) EarthwormEisenia fetidaAdult survival/ juvenile production Sb 2 (SO 4 ) 3 NOEC/LOEC adult survival = 617/697 mg Sb/kg NOEC/LOEC juvenile production = 60/86 mg Sb/kg Simini et al. (2002Simini et al. (2002) EnchytraeidEnchytraeus crypticus Adult survival/ juvenile production Sb 2 (SO 4 ) 3 NOEC/LOEC adult survival = 384/538 mg Sb/kg NOEC/LOEC juvenile production = 100/140 mg Sb/kg Kuperman et al. (2002Kuperman et al. (2002) SpringtailF. candidaAdult survival/ juvenile production Sb 2 (SO 4 ) 3 NOEC/LOEC adult survival = 100/126 mg Sb/kg NOEC/LOEC juvenile production = 100 /126 mg/kg Phillips et al. (2002Phillips et al. (2002) Office of Pollution Prevention and Toxics 25 Soil Toxicity Data
U.S. Geological Survey Open-File Report http://mrdata.usgs.gov/geochem/doc/home.htm 26
USGS National Stream Quality Accounting Network (1996-2000) http://pubs.usgs.gov/wri/wri014255/results/detect/pd01095.png 27
Office of Pollution Prevention and Toxics 28 ANTIMONY STATISTICS 1 (Metric tons of antimony content) United States: 2008 2009 2010 2011 2012 Mine production -- -- -- -- -- Smelter production: Primary W W W W W 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 oxide 2 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, average 3 (cents per pound) 279.5 235.6 401.2 650.3 564.5 Global mine production 185,000 r 154,000 178,000 r 183,000 r 174,000 e e Estimated. r Revised. W Withheld to avoid disclosing company proprietary data, -- Zero. 1 Data are rounded to no more than three significant digits, except prices. 2 Antimony content data were calculated by the U.S. Geological Survey. 3 New York dealer price for 99.5% to 99.6% metal, cost, insurance, freight U.S. ports. (USGS, 2012)