Summary of a Workshop on Interpreting Bioaccumulation Data Collected DuringRegulatory Evaluations of Dredged Material

摘要

Evaluating the environmental consequences of contaminant bioaccumulationresulting from dredged material disposal is a complex technical and regulatory problem. This problem is exacerbated by the high cost of bioaccumulation testing and the lack of explicit guidance on how bioaccumulation data should be interpreted and used within a regulatory program. Bioaccumulation is a measurable phenomenon, rather than an effect. Without specific information about biological effects (e.g., reduced survival, growth, reproduction in animals, cancer risk in humans) resulting from bioaccumulation, it is difficult if not impossible from a regulatory standpoint to objectively determine what level of bioaccumulation constitutes an 'unacceptable adverse effect.' Existing regulatory guidance attempts to overcome this with two approaches, both of which use low aquatic trophic level organisms and a reference-based comparison. In the first approach, the level of bioaccumulation of a specific contaminant is compared with a numerical effect limit, such as a Food and Drug Administration action level or a fish advisory. If the level of the contaminant in the organism exceeds the numerical limit, it is equated to an unacceptable adverse effect. If it does not, or there is no numerical limit, the second approach involves a comparison with animals exposed to a reference sediment. If bioaccumulation in the animals exposed to the dredged material exceeds that of animals exposed to the reference, a number of subjective factors are then evaluated to determine whether or not dredged material disposal will result in an 'unacceptable adverse effect' (U.S. Environmental Protection Agency (USEPA)/U.S. Army Corps of Engineers (USACE) 1991, 1994).