The assessment of bioaccumulation

Bioaccumulation of chemicals in biota may be a prerequisite for adverse effects on ecosystems. Since many of these effects can hardly be substantiated even in chronic laboratory scale ecotoxicity tests (e.g. impact of PCBs on hatching success of eggs, impact of DDE on eggshell thickness of birds or multi-generation effects) bioaccumulation constitutes an ecological risk by itself which has to be considered in an overall risk assessment of a chemical. A concept of assessing the risk of bioaccumulation is presented which proceeds by a stepwise refinement taking into account physico-chemical data and all available information from bioaccumulation studies as bioconcentration factor (BCF), elimination half-life time (CT50), organ specific bioaccumulation, and bound residues. The proposed classification of bioaccumulation into 4 risk assessment categories does not only consider the BCF, but also the complexity of bioaccumulation processes and may be applied to all organic chemicals under different legislations using the same stringent principles. Moreover, consideration of the complexity of bioaccumulation will also lead to a better understanding of biomagnification processes, i.e. enrichment of chemicals via food-webs, in ecosystems.