RP5 Endocrine Disruption and Pharmaceutical Issues
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(JEN-1117-829785) Assessing the Ecological Risk of Androgenic Growth Promoters.

Jensen, K¹, Kahl, M¹, Durhan, E¹, Makynen, E¹, Wilson, V², Lazorchak, J³, Miller, D⁴, Gray, L², Ankley, G¹, ¹ U.S. Environmental Protection Agency, Duluth, MN, USA² U.S. Environmental Protection Agency, Research Triangle Park, NC, USA³ U.S. Environmental Protection Agency, Cincinnati, OH, USA⁴ U.S. Environmental Protection Agency, Grosse Ile, MI, USA

ABSTRACT- There is significant interest in environmental contaminants that adversely impact fish through disruption of the hypothalamic-pituitary-gonadal (HPG) axis. Although most work has focused on changes in the axis caused by chemicals that bind to and activate estrogen receptors, there are a variety of contaminants that can affect HPG function through interactions with the androgen receptor. For example, recent research with water associated with cattle feeding operations in the US have associated morphological alterations in fish collected from the field with in vitro androgenic activity in water samples from affected sites. Some of these responses could be related to naturally-excreted steroids; however, much of the beef production in the US utilizes anabolic androgenic materials to promote muscle mass growth in the animals. One of the most commonly used chemicals for this purpose is the synthetic androgen precursor trenbolone acetate. Two metabolites of the acetate, 17- and 17-trenbolone, are comparatively stable in animal waste and the environment (half-lives of about 260 d). Recent studies from our labs have shown that both isomers bind with high affinity to the fathead minnow (Pimephales promelas) androgen receptor, and are highly potent in 21-d reproduction studies with this species, masculinizing females and decreasing fecundity at water concentrations in the low ng/L range. In other studies by our group, androgenic activity and the occurrence of 17- and 17-trenbolone were evaluated in water samples adjacent to a beef feedlot in the Midwest. Whole water samples from the site induced androgenic activity in vitro, and contained 17- and 17-trenbolone at ng/L concentrations comparable to those that adversely affected fathead minnow reproduction in the lab. This presentation will provide an integrated overview of these studies, and identify research and monitoring needs for a broader-scale assessment of the ecological risk of androgenic growth promoters. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Key words: fathead minnow, trenbolone, androgen, CAFO