Development and Use of Wildlife Inhalation Toxicity Reference Values for Ecological Risk Assessment

Transcription

1 Development and Use of Wildlife Inhalation Toxicity Reference Values for Ecological Risk Assessment Michael Anderson, California Environmental Protection Agency Ned Black, U.S. Environmental Protection Agency May 2006

2 Habitat: Chemicals of Potential Concern Representative Species of Concern Exposure & Toxicity Risk

3 Why Develop Inhalation Toxicity Reference Values for Wildlife? Soil vapor contamination significant issue at many Superfund or hazardous waste sites (e.g., Edwards AFB). High exposure potential fossorial or burrowing animals highly exposed population (Carlson 1996; Bench et al. 2001). Smaller species typically possess limited (< 2 acres) home ranges. Some burrowing wildlife are protected species (e.g., burrowing owl, kit fox, kangaroo rat)

4 Conceptual Exposure Model Pocket gopher example Soil Vapors Vadose Zone Ground Water Source

5 Why Develop Inhalation Toxicity Reference Values for Wildlife? Examples: California vole (Microtus californicus): estimates of up to 12 hours per day in burrow (Madison 1985).

6 Why Develop Inhalation Toxicity Reference Values for Wildlife? Examples (cont.): Panamint Kangaroo Rat (Dipodomys panamintinus): estimates of up to 23 hours per day in burrow (Kenagy 1973). Desert species.

7 Why Develop Inhalation Toxicity Reference Values for Wildlife? Examples (cont.): Mojave Ground Squirrel (Spermophilus mohavensis): estivates or hibernates from August to March in burrow. Protected desert species.

8 Why Develop Inhalation Toxicity Reference Values for Wildlife? Summary Verified exposure pathway Level of exposure is significant (ppm levels) possible in burrows

9 Sources of Inhalation Toxicity Reference Values Recently available data sources compiled in CA Edwards Air Force Base Vandenberg Air Force Base Google Search: Lee, B and Roy, M Toxicity reference values for inhalation of VOCs by terrestrial mammals. URS Corporation. NA SETAC Poster. Podolsky et al Toxicity reference values for inhalation of VOCs by terrestrial mammals. Environmental Health Associates; Neptune and Company. NA SETAC Poster. Archbold, et al Take a Deep Breath It s time to reconsider wildlife inhalation risk. Cantox Environmental; University of Toronto. NA SETAC Poster. Other Sources???

10 Sources of Inhalation Toxicity Reference Values Derivation: Laboratory inhalation toxicity studies (e.g., mice, rats, guinea pigs) from which a reference concentration is estimated from the literature No Observable Adverse Effect Concentration (NOAEC) for ecologically relevant chronic toxicity endpoints

11 Sources of Inhalation Toxicity Reference Values Assumptions and Uncertainties: Literature provides occupationally exposed rats (i.e., intermittent vs. continuous exposures). Convert to 24 hr/day exposure (most protective). Inhalation rate lab = inhalation rate field. May need LOAEC to NOAEC extrapolations (i.e., by uncertainty factors). Toxicity endpoint selected is ecologically relevant Comparable laboratory effects field effects

12 Chemical: Test Species Endpoint Chronic/ Subchronic Primary Study Information: Effect level Exposure Duration Body Weight (kg) Formula Weight Dose Reported in the Study (ppm) Nonadjusted TRV (mg/m 3 ) Dose-time Adjustment (to 24- hrs/day, 7-days/week) Toxico lly n sensit sens endp 1,1,1-Trichloroethane Gerbil neurological Subchronic NOAEL 24 hr day ,1,2-Trichloroethane Mouse survival, LC50 Subchronic LC50 6 hour *6hrs/24hrs = hepatic, renal, 6 hrs/day, ,1-Dichloroethane Cat hematopoetic Subchronic NOAEL days/wk *6hrs/24hrs*5days/7days = 361 1,1-Dichloroethene Guinea Pig survival Subchronic LOAEL 24 hrs/day * 6 hrs/day, 5 1,1-Dichloropropene Mouse respiratory Chronic NOAEL days/wk *5days/7days*6hrs/24hrs = ,2,3-Trichlorobenzene Rat hepatic Subchronic NOAEL 6 hrs/day; 7 days/wk *6hrs/24hrs = ,2,4-Trichlorobenzene Rat hepatic Subchronic NOAEL 6 hrs/day; 7 days/wk *6hrs/24hrs = behavior (rotorod performance, 6 hrs/day, 5 1,2,4-Trimethylbenzene Rat spontaneity) Chronic LOAEL days/wk *6hrs/24hrs*5days/7days = hrs/day; 7 1,2-Dichlorobenzene Rat hepatic Subchronic NOAEL days/wk *6hrs/24hrs = 102 1,2-Dichloroethane Rat systemic Chronic NOAEL 7 hrs/day, 5 days/wk *7hrs/24hrs*5days/7days = ,2-Dichloroethene Rat systemic Subchronic LOAEL 8 hrs/day; 5 days/wk *8hrs/24hrs*5days/7days = ,2-Dichloropropane Rat respiratory Subchronic LOAEL 6 hrs/day; 5 d/wk hrs/24hrs*5days/7days = hrs/day, 1,2-DichlorotetrafluoroethRat maternal wt. gai Chronic NOAEL 7days/week m * 86.47/24.45 * 6 hrs/24 hrs = ,3,5-Trimethylbenzene Rat behavior (rotorod performance, spontaneity) Chronic LOAEL 6 hrs/day, 5 days/wk *6hrs/24hrs*5days/7days = hrs/day; 7 1,3-Dichlorobenzene Rat hepatic Subchronic NOAEL days/wk *6hrs/24hours = ,4-Dichlorobenzene Rat hepatic Subchronic NOAEL 6 hrs/day; 7 days/wk *6hrs/24hours = Butanone (MEK) Mouse development Chronic NOAEL 7 hrs/day *7hrs/24hrs = Hexanone Rat neurological Subchronic LOAEL 8 hrs/day; 5 days/wk *8hrs/24hrs*5days/7days = Methylnaphthalene Mouse olfactory Chronic LOAEL 6 hrs/day; 5 days/wk *6hrs/24hrs*5days/7days = 10.4 Acetone Rat developmental Chronic NOAEL 6 hr/day; 7 days/wk *6hrs/24hrs = 1305 systemic (decreased CFU-E

13 Proposed Region 9 BTAG Effort BTAG = U.S. EPA Region 9 Biological Technical Assistance Group Rationale we need to apply consistent, defensible set of toxicity criteria Approach identify critical study, including: data review assess ecotoxicologically relevant endpoints select NOAEC/LOAEC Initial Effort Develop TRV for 10 to 12 choice VOCs proposed by group members. Document decisions EcoNOTE

14 Screening Approach TRV Expressed as [mg/m3] Modeled soil vapor conc. versus direct measure Most protective assumption: [Burrow air] = [soil vapor] Generate hazard quotient: Burrow air (mg/m3) TRV (mg/m3)

15 Screening Level Yes Animal Burrow Air Evaluation Ph E tland or tic Habitat Only? No Yes Terrestrial Ecological Habitat Onsite? No pare Site to USEPA on 9 Soil PRG Screening Level Background Soil Risk and Hazard Quotient pare Site to USEPA on 9 Soil PRG Screening Level Soil Risk and Hazard Quotient te and ansport Model Assessment eachate Groundwater Leachate Conc. Soil Gas Investigation No Soil Gas Data DTSC J&E Model Screening Level Soil Gas Risk & Hazard Quotient Soil Gas Data? Yes

16 Additional Considerations Validation of the TRVs Edwards AFB findings Integration/Comparison with HHRA Compare to ecological soil vapor screening levels to indoor air human health risk levels. Are human health levels protective of eco receptors?

17 CONCLUSIONS Inhalation of soil vapors significant exposure pathway for burrowing animals. A burrow air screening evaluation is recommended for ERA. Inhalation toxicity databases exist (e.g., ATSDR) for laboratory animals. Some ecological inhalation toxicity criteria have been proposed. Other sources? BTAG Goal Develop and select a consistent, scientifically defensible set of inhalation TRVs for wildlife