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(86-02) From population relevant endpoints to biomarkers - a testing strategy for EDCs. Wenzel, Andrea*,1, Schäfers, Christoph1, 1 Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), 57392 Schmallenberg, Germany ABSTRACT- Estrogen-receptor mediated reactions were investigated focusing on the population level of fish in order to develop a tiered testing strategy for endocrine disrupters. The main objective of the fish studies was to assess the significance of estrogenic effects gathered in in-vitro and short-term in-vivo tests for the population level of fish being the main protection target of aquatic ecotoxicology. A full life cycle test is under discussion in several international expert groups (e.g. OECD-EDTA) as a definite test at tier-3 level to ultimately confirm endocrine effects in fish. Four estrogenic substances were tested in fish full life cycle tests with zebrafish, all of them showing most sensitive effects on the fertilization capacity. Effects on the endpoints pre-adult growth, time until first spawning, egg production and fertilization rate are more or less correlated. Whereas male mating behaviour is able to recover after periods without exposure, fertilization rates are obviously not. The fertilization rate seems to be the most sensitive, most permanent and - as follows - most relevant endpoint in terms of population dynamics. It enables clear dose-response relationships (ECx-values) and sensitive NOEC values because of the low control variances with zebrafish rather than with other species, and it is highly reproducible. It is clearly correlated to male vitellogenin levels, which seem to be of equal sensitivity. The presentation will also include information on whether a short term exposure exhibits similar sensitivity of the vitellogenin response compared to full life cycle exposure, whether adult male blood plasma is necessary or juvenile body homogenates are sufficient for vitellogenin determination, and whether fathead minnow is of similar sensitivity compared to zebrafish. Key words: endocrine disruptors, zebra fish, life cycle tests, vitellogenin |
