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(P458) Relationships between Residues of AhR Agonists in Fish and Concentrations in Water and Sediment.
Cook, Philip*,1, Burkhard, Lawrence1, Mount, David1, Lukasewcyz, Marta1, 1 US-EPA, NHEERL, Mid-Continent Ecology Division, Duluth, MN, USA
ABSTRACT- The bioaccumulation visualization approach of Burkhard et al. (2002) can be effectively used to describe the bioacumulation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) that are toxic to vertebrates through an aryl hydrocarbon receptor (AhR) mediated mechanisms of action. The toxicities of these chemicals are optimally defined on the basis of residues in tissues of organisms. BAFs and BSAFs therefore define the relationship between toxicity risks and exposure levels in water and sediments. Prediction and measurement of bioaccumulation for AhR agonists is difficult because of metabolism in the food chain and extremely trace levels present in aquatic ecosystems, particularly in water. Examples will be provided to illustrate how these complexities may be overcome. As with other very hydrophobic chemicals, differences in the distribution of each AhR agonist between sediment and water; the relationship of food chains to water and sediment; and the length of the food chains are site-specific factors which influence BAFs and BSAFs. Preliminary attempts to extrapolate trophic level specific BAFs and BSAFs for AhR agonists across aquatic ecosystems suggest that lipid and organic carbon normalization, coupled with adjustments for the three basic ecosystem factors, will allow useful estimates of bioaccumulation. If so, this will facilitate integrated water and sediment quality criteria development and application for AhR agonists. This abstract does not necessarily reflect U.S. EPA policy.
Key words: dioxins, bioaccumulation, fish, sediment
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