(PW260) Uncertainty in Food Web Models for Sediment Exposures.

McKean, D1, 1 Raymond Walters College, Cincinnati, OH, USA

ABSTRACT- U.S. Environmental Protection Agency guidance for ecological risk assessments stipulates the use of highly conservative food web model estimates for intake. Compounds such as DDT and its related byproducts, are highly lipophilic, resulting in the potential for significant bioaccumulation. EPA guidance suggests the use of octanol-water partition coefficients to estimate uptake of bioaccumulative compounds. However, measured uptake of DDT in aquatic systems can be six orders of magnitude less than values estimated from octanol-water partition coefficient models. Estimate comparisons will be presented that illustrate the magnitude of variation in DDT exposure estimates from models and measured values. These exposure estimates have significant impact on the risk estimates derived from them and the risk management decisions upon which they are based.

Key words: sediment, risk, ddt

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