oxide metal overview of antimony trioxide (ato) workplan risk assessment sharon oxendine office of...

OxideMetal

Overview of Antimony Trioxide (ATO) Workplan Risk Assessment

Sharon OxendineOffice of Pollution Prevention and Toxics November 13, 2013

Antimony Trioxide (ATO)CASRN 1309-64-4

http://www.americanelements.com/Chloride_nitrate_etc_page.html.html

http://www.americanelements.com/Chloride_nitrate_etc_page.html.html

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


* 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


× Human health risks were not the focus of this assessment

ATO

Antimony Compounds

Conceptual Model for ATO Risk Assessmentfocuses on ecological risks resulting from

industrial releases to water


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.


Criteria for Selection of TRI Facilities


NAICS codes

Reported water releases

Availability of “7Q10” streamflow data

Monitoring: USGS-NWIS & EPA STORET

9

Monitoring Data:


Can we generalize from this data to other regions?


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.



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


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


Risk Summary


Media Type Organism Endpoint COC

MonitoringData

ModeledData

Water

C. viridissima 96-hour LC50 = 1.77 mg/L 354 ppb (acute) No exceedance One exceedance

P. Promelas 30-day GMATC = 1.62 mg/L 162 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


Selected TRI facilities ( ) are shown as a point of reference

Conclusion

Minimal risks are expected for ecological organisms:


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


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


• 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 Austin Jay Jon

Stanley Barone Sharon Oxendine

Cathy Fehrenbacher Wen-Hsiung Lee

Nhan Nguyen Tim Lehman

Louis Scarano Sara Pollack

Christina Cinalli Emma Lavoie

Rick Fehir Kirsten Hesla

Contract SupportPortions of this document were developed with support

from SRC, Eastern Research Group and Versar.

Thank you!

Test Organism Species Endpoint Antimony Compound Value Reference

Fish Pagrus major 96-hour LC50 SbCl3 6.9 mg Sb/L Takayanagi (2001)

Aquatic invertebrate Chlorohydra viridissima 96-hour LC50 SbCl3 1.77 mg Sb/L TAI (1990)

Aquatic plant Pseudo kirchneriella subcapitata

72-hour LC50

(growth rate)SbCl3 EC50 > 36.6 mg/L

NOEC = 2.11 mg Sb/LLOEC of 4.00 mg Sb/L

GMATC = 2.91 mg Sb/L

Heijerick and Vangheluwe (2004)

Aquatic plant P. subcapitata 72-hour LC50

(growth rate)Sb2O3 NOEC = 0.396 mg Sb/L

LOEC = 1.32 mg Sb/LGMATC = 0.723 mg Sb/L

LISEC (2001)

Fish Pimephales promelas 30-day (growth) SbCl3 NOEC = 1.13 mg Sb/LLOEC = 2.31 mg Sb/L


Kimball (1978)

Fish P. promelas 30-day (growth) Sb2O3 NOEC >0.0075mg /L LeBlanc and Dean (1984)

Aquatic invertebrate Daphnia magna 21-day (reproduction)

SbCl3 NOEC = 1.74 mg Sb/LLOEC = 3.13 mg Sb/L


Heijerick and Vangheluwe (2003b)a)

Aquatic Toxicity Data


Sediment Toxicity Data


Test Organism Species Endpoint AntimonyCompound Value Reference

Amphipod Hyalella azteca Survival/growth/reproduction

SbCl3 NOEC = 87 mg Sb/kg ww (124 mg Sb/kg dw)

Heijerick and Vangheluwe (2003a)

Oligochaete Lumbriculus variegatus

Survival/growth/reproduction


Heijerick and Vangheluwe (2005a)

Midge larvae Chironomus riparius

Survival/growth/reproduction


Heijerick and Vangheluwe (2005b)

Test Organism Species Endpoint Antimony Compound Value Reference

Springtail Folsomia candida Reproduction Sb2O3 NOECreproduction = 999 mg Sb/kg dwLOECreproduction=2,930 mg Sb/kg dw

Moser (2007)

Earthworm Eisenia fetida Adult survival/ juvenile production

Sb2(SO4)3 NOEC/LOEC adult survival = 617/697 mg Sb/kgNOEC/LOEC juvenile production = 60/86 mg Sb/kg

Simini et al. (2002)

Enchytraeid Enchytraeus crypticus

Adult survival/ juvenile production

Sb2(SO4)3 NOEC/LOEC adult survival = 384/538 mg Sb/kg NOEC/LOEC juvenile production = 100/140 mg Sb/kg

Kuperman et al. (2002)

Springtail F. candida Adult survival/ juvenile production

Sb2(SO4)3 NOEC/LOEC adult survival = 100/126 mg Sb/kgNOEC/LOEC juvenile production = 100 /126 mg/kg

Phillips et al. (2002)


Soil Toxicity Data

U.S. Geological Survey Open-File Report

http://mrdata.usgs.gov/geochem/doc/home.htm

http://mrdata.usgs.gov/geochem/doc/home.htm

USGS National Stream Quality Accounting Network (1996-2000)

http://pubs.usgs.gov/wri/wri014255/results/detect/pd01095.png

27

http://pubs.usgs.gov/wri/wri014255/results/detect/pd01095.png


ANTIMONY STATISTICS1

(Metric tons of antimony content)

United States: 2008 2009 2010 2011 2012Mine production -- -- -- -- -- Smelter production: Primary W W W W W Secondary 3,180 3,020 3,520 3,230 3,730Exports: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) 279.5 235.6 401.2 650.3 564.5Global 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)

oxide metal overview of antimony trioxide (ato) workplan risk assessment sharon oxendine office of...

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