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REPRODUCTIVE TOXICITY OF ANDROGENIC GROWTH PROMOTORS IN THE FATHEAD MINNOW
Citation:
Jensen, K M., M D. Kahl, E A. Makynen, M. W. Hornung, AND G T. Ankley. REPRODUCTIVE TOXICITY OF ANDROGENIC GROWTH PROMOTORS IN THE FATHEAD MINNOW. Presented at 2002 SETAC Annual Meeting, Salt Lake City, UT, June 16-20, 2002.
Description:
Reproductive Toxicity of Androgenic Growth Promoters in the Fathead Minnow. Jensen, KM*, Kahl, MD, Makynen, EA, Hornung, MW, Ankley, GT. U.S. Environmental Protection Agency, Duluth, MN. Trenbolone acetate is a synthetic steroid which is extensively used in the US as a growth promoter in beef production. The acetate is administered to livestock via slow release implants; it is converted by the animal to beta-trenbolone, a relatively potent androgen receptor agonist. Both beta-trenbolone and it's stereoisomer, alpha-trenbolone, are significant excretory products from beef cattle. Recent studies indicate they are comparatively stable in waste, suggesting the potential for exposure to aquatic animals via direct discharge and/or run-off. Little is known, however, concerning the toxicity of trenbolone to fish. Our goal was to assess the effects of alpha- and beta-trenbolone on reproductive endocrinology in the fathead minnow. Male and female fish were exposed for 21-d to graded concentrations of the test chemicals ranging from 0.005 to 50 ug/l (beta-trenbolone) or 175 to 7000 ug/l (alpha-trenbolone). Both compounds were highly androgenic in the fish, as evidenced by the de novo production in females of dorsal tubercles, structures normally present only in mature males. Fecundity also was significantly affected by the two androgens, with a measured no-observable effect concentration for beta-trenbolone on the order of 0.0012 ug/l. The potential effects of these chemicals on animals exposed to feedlot wastes currently are unknown, but warrant further investigation. This abstract does not affect EPA policy.