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Effects of xenooestrogens on the fish life cycle

: Schäfers, C.; Schmitz, A.; Wenzel, A.

Richter, A.:
Second Statusseminar Endocrine Disrupters 2001. Proceedings : Berlin, Germany, 2nd-4th April 2001
München: GSF-Forschungszentrum für Umwelt und Gesundheit, 2001
ISBN: 3-928875-03-5
Statusseminar Endocrine Disrupters <2, 2001, Berlin>
Conference Paper
Fraunhofer IUCT ( IME) ()

Oestrogen-receptor mediated reactions were investigated with respect to their impact on endpoints of a fish full life cycle study in order to derive critical effect concentrations of different kinds of anthropogenic estrogens: Ethinyloestradiol (EE2) as the most important contraceptive oestrogen, ptert-Octylphenol (OP) and Bisphenol A (BPA) as industrial chemicals, and Genistein (GEN) as a phytohormone. Fish full life cycle studies were performed in flow-through systems or under semistatic conditions. Stage specific mortalities, length development, time until reproduction, egg production and fertilisation rate were monitored. Estrogenic effects at effective concentrations during the life cycle seem not to be interrelated with early life stage effects nor with impacts on final sex ratio. The other endpoints such as retardation of pre-adult growth, prolongation of time until first re-production, decrease of egg production and decrease of fertilisation rate are highly correlated, forming an endocrine disrupting syndrome being specific for responses to estrogenic substances. Whereas male mating behaviour can be performed after some retardation and is able to recover at least after long periods without exposure, resulting also in recovery of egg production, fertilisation rates seem to be irreversibly affected. All substances caused a more or less pronounced estrogenic syndrome. The clear concentration-response relationship enabled calculations of EC50 values based on the reduction of fertilisation rates. The EC50s of OP and BPA were determined being one order of magnitude below acute LC50s. The EC50 of GEN was less than one order of magnitude below lethal early life stage toxicity due to the multiple molecular targets of GEN, especially the inhibition of protein kinase enzymes inhibiting metabolism. The EC50 of EE2 was determined with 1.1 ng/l, being 6 orders of magnitude below acute and two orders of magnitude below prolonged lethal toxicity. In terms of environmental risk assessment, the estrogenic risk of OP is covered by the uncertainty (safety) factor on the acute LC50 value. The estrogenic property of GEN would have been covered by performing an early life stage test and applying a factor of 10. The fast biodegradation minimises the environmental risk. EE2, however, clearly causes effects far below standard test effect concentrations being in the range of environmental concentrations without any safety factor.