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EVALUATION OF FADROZOLE AS AN ENDOCRINE DISRUPTOR IN FATHEAD MINNOW (PIMEPHALES PROMELAS)
Citation:
Jensen, K M., K Jensen, M D. Kahl, J J. Korte, E A. Makynen, M. W. Hornung, AND G T. Ankley. EVALUATION OF FADROZOLE AS AN ENDOCRINE DISRUPTOR IN FATHEAD MINNOW (PIMEPHALES PROMELAS). Presented at SETAC Annual Meeting, Baltimore, MD, November 11-15, 2001.
Description:
The EPA has received a legislative mandate to develop and implement standardized screening and testing methods to identify and assess potential endocrine disrupting chemicals (EDCs). The objective of this research was to evaluate a short-term EDC screening/testing assay which assesses alterations in reproduction and endocrine function in the fathead minnow (Pimephales promelas) using fadrozole, an inhibitor or aromatase (a cytochrome P450-based enzyme that converts testosterone to B-estradiol). Reproductively-active fish were continuously exposed to nominal fadrozole concentrations of 0, 2, 8, oe 50 ug fadrozole/L for 21-d. Endpoints assessed included plasma sex steroid concentrations (B-estradiol, testosterone and 11-ketotestpsterpme), vitellogenin, gonadosomatic indices (GSI), gonad histology, secondary sex characteristics, fecundity, and larval survival. Fadrozole was measured in both exposure water and parental fish. Fadrozole caused a sigificant decrease in fecundity, concurrent with a dose-dependent decrease in plasma B-estradiol in females, a response consistent with inhibition of aromatase. Decreased vitellogenin and abnormal ovarian histology were also observed in females exposed to fadrozole. This study, in combination with other research evaluating various estrogenic/androgenic chemicals, demonstrates the utility of the assay and also provides insights into the evaluation of various reproductive endpoints for assessing the effects of EDCs in fish.