Fish Show Hormones Disruptor Effect Nationwide

"The finding of a correlation between hormone levels and contaminant levels in fish from such diverse locations is both a cause for concern and a call for further investigation," said Dr. Gordon Eaton, USGS director.

The national reconnaissance study is the broadest investigation to date of the potential for endocrine disruption in fish, but it did not assess the severity of the effect. "Since altered sex hormones may cause reproductive impairment, we need to follow up this reconnaissance study with detailed assessments of fish reproduction at selected sites," said Steve Goodbred, USGS research scientist and senior author of the report.

More than 600 common carp were collected and analyzed from 25 streams in 13 States and the District of Columbia. The streams selected drain areas with a wide range of land uses and different degrees of contamination. Results of the study indicate significant differences in sex hormones and vitellogenin, an estrogen-controlled protein necessary for egg development in fish and birds. Although some of these differences probably result from natural variability, correlations between contaminants and the levels of sex hormones in carp indicate that some of the site-to-site differences were associated with certain contaminants.

It is not yet possible to pinpoint which specific contaminants or factors may be related to the significant differences noted among the hormones. The groups of contaminants that were significantly correlated with hormones were pesticides in water, phenol compounds in streambed sediments, and organochlorine compounds in biological tissue.