This study monitored the Bow Creek watershed, Nebraska, to determine the occurrence and endocrine effects of agrichemicals. This watershed is dominated by beef cattle and row crops. Steroid hormones were not found at four sites. Pesticides were detected. Evidence of defeminization was observed in caged fathead minnows, however these effects could not be attributed to any of the pesticides detected.
Jeffries, M.K., K.I. Abbott, T. Cowman, and A.S. Kolok 2011. The occurrence and endocrine effects of agrichemicals in a small Nebraska, USA watershed. Environmental Toxicology and Chemistry, Jul 5. doi: 10.1002/etc.615.
Agricultural and Occupational Health, University of Nebraska – Medical Center, Omaha, Nebraska, USA.
Abstract (National Library of Medicine):
The Bow Creek watershed, Nebraska, USA is dominated by the production of beef cattle and row crops; therefore, surface waters are likely to receive runoff containing steroid hormones and pesticides. The goal of the current study was to determine the occurrence and endocrine effects of agrichemicals in this watershed. To accomplish this, four sites within the watershed – Pearl, Bow, and East Bow Creeks and a site at the confluence with the Missouri River – were selected. In June of 2008, polar organic chemical integrative samplers (POCIS) were deployed at each site, whereas in June of 2009, water and sediment samples were collected. Caged fathead minnows (Pimephales promelas) were deployed at all of the selected sites in both years. Analysis of these samples revealed that steroid hormones were not present; however, pesticides were present in POCIS extracts and water samples. In general, the amount of pesticides was higher in POCIS retrieved from Pearl and Bow Creeks than in POCIS from East Bow Creek and the Confluence. This variation between sites appeared to be related to row crop density, as row crop land cover surrounding the Pearl and Bow Creek sites was higher than that surrounding the East Bow and Confluence sites. In order to determine the endocrine effects of agrichemicals within this watershed, the hepatic mRNA expression of vitellogenin and estrogen receptor α (ERα), as well as the gonadal expression of P450 aromatase A, was determined for the caged minnows. Females deployed at East Bow Creek and the Confluence experienced decreases in the expression of ERα suggesting that these females had been defeminized; however, this defeminization could not be attributed to any of the pesticides detected at these sites.