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2L - Immunotoxicity - genotoxicity - ED (WEP/118) Mixture effects of endocrine disrupting chemicals: Considerations for a predictive assessment. Frische, T.1, Backhaus, T. 1, Faust, M.2, Meyer, W.1, Scholze, M.3, Grimme, L.H. 1, 1 University, Bremen, Germany2 F & B Environmental Consulting, Bremen, Germany3 The School of Pharmacy, London, UK ABSTRACT- An enormous expansion of public awareness as well as scientific research on endocrine disruption has been observed in the past years. Despite this, some principle limitations hamper the risk assessment of chemicals exhibiting adverse effects on endocrine functions in wildlife. Firstly, there is no consensus yet on the experimental methodology to adequately assess endocrine disrupting effects (e.g. in vitro assays, in vivo studies, monitoring). Secondly, the magnitude and relevance of environmental exposure to known, suspected and probably unknown endocrine disrupters is still under discussion. In this context, an important but rather unexplored question arises from the consequences of multiple exposure situations. Indeed, exposure to spatially as well as temporarily varying chemical mixtures is typically for the environment. As it is not possible to experimentally address all combinations of chemical mixtures, scientifically sound concepts for predicting combination effects are essential. The purpose of this presentation is to debate the applicability of the most widespread concepts for the predictive assessment of mixture toxicity to endocrine effects: Concentration Addition (CA) and Independent Action (IA). Both have been demonstrated in several cases to reliably predict mixture toxicities of similarly (CA) and dissimilarly acting toxicants (IA) on the basis of the toxicity of individual mixture components. Therefore, general prerequisites and demands of both concepts regarding necessary input data will be analysed with respect to different endpoints widely used in endocrine effect assessment for the aquatic environment. Potentials as well as restrictions of both concepts will be highlighted and condensed in preliminary conclusions regarding their applicability in the risk assessment of endocrine disrupting chemicals. This research is conducted within the EU-project ACE (Analysing combination effects of mixtures of estrogenic chemicals in marine and freshwater organisms, http://www.the-ace-project.info). Key words: endocrine disruption, mixture effects, predictive assessment |
