The Assessment of Bioaccumulation

Abstract

Bioaccumulation and biomagnification of chemicals in biota may be a prerequisite for adverse effects in individuals, species, and ecosystems. From disastrous events posed by xenobiotic chemicals, e.g. PCBs, Dioxins, DDT etc. it must be concluded retrospectively that such impacts cannot be avoided and predicted sufficiently with existing hazard and risk assessment strategies. Even sophisticated testing for chronic effects cannot rule out a possible risk of retarded effects completely. Since adverse effects as a consequence of bioaccumulation may become obvious long after a chemical’s release and recovery may be retarded if not even hampered, authorities concerned with notification and registration of chemicals need a conceptual approach how to minimise risks posed by dangerous substances. Different concepts for the assessment of bioaccumulation (USA, Canada, Japan, Netherlands, ECETOC and EU) are critically discussed and compared regarding their precautionary principles. The risk assessment for bioaccumulation presented here is more comprehensive than the EU Technical Guidance Document (TGD) for new and existing substances. It gives guidance how to proceed stepwise from testing bioaccumulation, ranking of results, decision-making on the basis of triggered ecotoxicological tests and finally to an assessment of risks for bioaccumulation and biomagnification. Going beyond the scope of existing concepts this approach takes into account the complexity of bioaccumulation processes including uptake and depuration kinetics, bioconcentration factor, metabolism, and bound residues, relating these data to critical body burden concentrations. The risk assessment of biomagnification is driven by the outcome of the bioaccumulation assessment. If following the refined risk assessment recommended by the TGD an uncertain risk of biomagnification in ecosystems cannot be ruled out, the application of an unsafety factor of 10 on the final PEC/PNEC is proposed for discussion.