PT07 Chemical and Biological Analysis of Endocrine Disrupting Compounds
Exhibit Hall
8:00 AM - Tuesday
(PT113) Effects of Imidazole Fungicides on Reproductive Endocrinology in the Fathead Minnow.
Jensen, K1, Kahl, M1, Durhan, E1, Villeneuve, D1, Linnum, A2, Makynen, E1, Ankley, G1, 1 U.S. Environmental Protection Agency, Duluth, MN, USA2 Senior Service America, Inc., Duluth, MN, USA
ABSTRACT- A variety of substituted imidazoles serve as effective fungicides through their ability to block CYP51, a cytochrome P450 isozyme critical to ergosterol biosynthesis. However, imidazole fungicides can affect activities of other CYP isozymes in different taxa. CYP19 (aromatase) in vertebrates converts testosterone to 17
-estradiol and, as such, is critical to reproductive endocrine function. Evidence, largely from mammalian studies, suggests that some fungicides may act as endocrine-disrupting chemicals (EDCs) through inhibition of CYP19. The purpose of the present study was to evaluate the effects of two imidazole fungicides, prochloraz and fenarimol, on reproductive success and endocrinology in the fathead minnow (Pimephales promelas). Pairs of reproductively-active male and female fathead minnows were exposed via the water to 0.03, 0.1, and 0.3 mg prochloraz/L, or 0.1 and 0.6 mg fenarimol/L for 21 d using a protocol developed to detect EDCs with different modes/mechanisms of action. Both chemicals significantly decreased fecundity of the fish. Prochloraz and fenarimol also depressed plasma vitellogenin concentrations in the females, a response consistent with inhibition of aromatase activity. In addition, prochloraz caused a concentration-dependent decrease in plasma estradiol concentrations in the females. The results of this study indicate the potential for imidazole fungicides to act as EDCs in fish, and further illustrate the utility of the 21-d fathead minnow assay as a test system for identifying EDCs. This abstract does not necessarily reflect EPA policy.
Key words: endocrine disruption, fathead minnow, prochloraz, fenarimol