PH11 Bioaccumulation and Biotransformation of POPs
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH109) Differential uptake of PCBs by various small mammal species.
Moore, M.1, Salatas, J.1, Sauvage, R.2, Ginn, T.1, 1 Exponent Ecological Sciences Group., Bellevue, WA, USA2 El Paso Corp., Houston, TX, USA
ABSTRACT- Assessment of risk to terrestrial wildlife at polychlorinated biphenyl (PCB) contaminated sites often focuses on exposure of higher trophic level consumers that prey on small mammals. Dietary exposure for these species is often estimated using food web models. In this approach, PCB concentrations in potential prey are often estimated from soil concentrations using bioaccumulation factors (i.e., reported ratios of PCB concentrations in small mammals and soil). Published PCB bioaccumulation factors for small mammals from soil, however, are limited to a small number of species and narrow range of PCB concentrations. As a result, there is considerable uncertainty associated with use of bioaccumulation factors from the literature to estimate exposure for terrestrial receptors. In this study, whole body PCB concentrations were measured in short-tailed shrew (Blarina brevicauda), white-footed mouse (Permyscus leucopus), meadow jumping mouse (Zapus hudsonius), rice rat (Oryzomys palustris), hispid cotton rat (Sigmodon hispidus), pine vole (Microtus pinetorum), and prairie vole (Microtus ochrogaster), from areas with mean PCB concentrations in soil up to 228 mg/kg. PCB concentrations in small mammals clearly varied in relation to concentrations in soil, however accumulation rates were also highly variable between species. PCB concentrations in shrews were up to 70 fold higher than PCB concentrations in mice captured from the same area. In general, PCB concentrations were highest in shrews, lowest in voles, and intermediate in mice and rats. Differences in accumulation rates between taxa are presumably due, in part, to dietary habits. Within a single species, accumulation rates appeared to be relatively constant across the range of soil PCB concentrations evaluated. These results indicate that small mammals vary widely in their uptake of PCBs and that the dietary composition of the receptor species being modeled must be considered. Failure to account for differences in PCB bioaccumulation in small mammals or the dietary composition of the receptor species could result in dramatic over- or underestimates of exposure.
Key words: PCBs, bioaccumulation, exposure