Assessing the Bioavailability of Arsenic from CCA-Impacted Soils for Use in Risk Assessment. Y. W. Lowney, A. D. Nicholson, G. C. Hook, and S. Severn, Exponent Environmental Group, 4940 Pearl East Circle, Suite 300, Boulder, Colorado 80301
In support of an effort to establish health-based remedial goals, we assessed the bioavailability of arsenic from soils at two sites where chromated copper arsenate (CCA) was used to treat wood products. Hexavalent chromium in site soils could also present environmental or health hazards; however, this study evaluated arsenic only, because abundant reducing agents (i.e., wood chips) at most wood treatment sites keep concentrations of hexavalent chromium low. Arsenic bioavailability from site soils was assessed using in vitro bioaccessibility tests (modified from a test developed by Ruby et al.). The resulting bioaccessibility estimates represented likely upper bounds for arsenic bioavailability, so these values were compared to arsenic bioavailability values established by other researchers through in vivo testing, further constraining our site-specific bioavailability estimates. Results indicated that bioavailable arsenic from these two sites is substantially less than total arsenic concentrations, and this information will be useful in negotiating site-specific remedial goals for arsenic. This method has been used previously in studying mining- and smelting-related sites, but we believe this to be the first application to CCA-impacted sites.
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