Bioavailability of genotoxic mixtures in soil
- Texas A and M Univ., College Station, TX (United States). Dept. of Veterinary Anatomy and Public Health
Contaminated media at Superfund sites typically consist of complex mixtures of organic and inorganic chemicals which are difficult to characterize, both analytically and toxicologically. The current EPA approach to risk assessment uses solvent extraction to remove chemicals from the soil as a basis for estimating risk to the human population. However, contaminants that can be recovered with a solvent extract may not represent the mixture of chemicals that are available for human exposure. A procedure using an aqueous extraction was investigated to provide a more realistic estimate of what chemicals are bioavailable. A study was conducted with two soil types: creosote-contaminated sandy soil and coal tar-contaminated clay soil spiked with benzo(a)pyrene [B(a)P], and trinitrotoluene (TNT). Samples were extracted with hexane:acetone and water titrated to pH2 and pH7. HPLC analysis demonstrated up to 35% and 29% recovery of contaminants using the aqueous extracts. The estimated cancer risk for the aqueous extract was one order of magnitude less than that for solvent extracts. Analysis using the Salmonella/microsome assay demonstrated that solvent extracts were genotoxic (133 revertants/mg) with metabolic activation while aqueous extracts of clay soil were not genotoxic. Sandy soil showed genotoxicity both with and without metabolic activation. These results suggest that solvent extraction techniques may overestimate the concentration of contaminants that are available for human exposure and, hence, the risk associated with the presence of the contaminants in soil.
- OSTI ID:
- 422863
- Report Number(s):
- CONF-9605266-; TRN: IM9707%%170
- Resource Relation:
- Conference: 9. Annual conference on hazardous waste remediation, Bozeman, MT (United States), 8-10 Jun 1994; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings of the 1996 Hazardous Substance Research Center/Waste-management Education and Research Consortium joint conference on the environment; Erickson, L.E. [ed.] [Kansas State Univ., Manhattan, KS (United States)]; Grant, S.C. [ed.] [Haskell Indian Nations Univ., Lawrence, KS (United States)]; Tillison, D.L.; McDonald, J.P. [eds.]; PB: 706 p.
- Country of Publication:
- United States
- Language:
- English
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