PARENT SESSION
MP3 - Endocrine Disruption
Chair: Henry, Tala1, 1 U.S. EPA, NHEERL, Duluth, MN
Co-chair: Guiney, Patrick2, 2 S.C. Johnson & Son, Inc., Racine, WI
2:10 PM to 5:30 PM - Monday, 18 November 2002
Room Ballroom H
(272) Effects of atrazine in a short-term fathead minnow reproductive assay.
Bringolf, Robert*,1,2, Summerfelt, Robert1,2, Belden, Jason2,3, 1 Iowa State University, Department of Animal Ecology, Ames, Iowa, USA2 Iowa State University, Interdepartmental Program in Toxicology, Ames, Iowa, USA3 Iowa State University, Department of Entomology, Ames, Iowa, USA
ABSTRACT- Atrazine is the most extensively used herbicide in the United States. Part per million concentrations of atrazine have been reported in agricultural runoff, it is detectable in surface waters and precipitation throughout the year, and it has been found in ground water sources of drinking water. In addition, recent studies indicate that atrazine may be a potent endocrine disrupting compound at low (ppb) concentrations. For these reasons, we examined the effects of atrazine (5 and 50 ppb) on several endpoints related to reproductive fitness in fathead minnows (Pimephales promelas) in a 21-d static exposure. Estradiol (0.5 ppb) was included as a positive control treatment. Endpoints examined in adult fish during and after the exposures included survival, egg production, number of spawns, eggs/spawn, relative gonad weight, number of nuptial tubercles, plasma vitellogenin concentration, and gonad histology. Eggs produced during the exposures were hatched and reared in control water and % embryos fertilized, % hatch, % larvae survival were evaluated. Atrazine exposure concentrations (validated with gas chromatography) were >70% of nominal in all water samples taken throughout the exposure period (n = 32). Testis weight and % fertilization were less in the atrazine exposed fish, but the differences in these and other endpoints were not statistically significant because of the large variability in all of the measures in treated and control groups. The positive controls (exposed to estradiol) were significantly different from atrazine exposed fish and control fish (unexposed) for nearly all endpoints. These results suggest that atrazine did not have strong estrogenic effects in fathead minnows and did not cause overt reproductive toxicity at environmentally relevant concentrations.
Key words: atrazine, endocrine disruption, reproduction, fish