In June 2014, a research team led by the U.S. Geological Survey (USGS) Science Center in Leetown, West Va., published a study finding that fish in three Pennsylvania river basins showed the condition known as “intersex,” where male fish contain immature eggs or show other female characteristics. The study found intersex fish in the Delaware, Ohio, and Susquehanna River basins in the Keystone State. Previous USGS work has documented intersex fish in the Potomac River basin and in rivers basins around the country.
The intersex condition is thought to result from exposure to chemicals called “endocrine disruptors.” According to the USGS news release on the Pennsylvania study, the authors believe that the sources of chemicals causing the condition are probably a complex mixture of substances from agricultural sources, wastewater treatment plant effluent, and other wastewater; more research is being conducted to “characterize the sources and timing of exposure to these complex mixtures in relation to fish health.”
The study is “Reproductive Health Indicators of Fish from Pennsylvania Watersheds: Associations with Chemicals of Emerging Concern,” by V.S. Blazer et al., published in Environmental Monitoring and Assessment, October 2014, Volume 186/Issue 10, pages 6471-6491. Information on the study is available in the following USGS news release: “Intersex Fish Now in Three Pennsylvania River Basins,” 6/30/14, online at http://www.usgs.gov/newsroom/article.asp?ID=3921#.VDU7Axa_4_s.
Information on previous USGS work on intersex fish nationwide is available in the following news release: “Widespread Occurrence of Intersex Bass Found in U.S. Rivers,” 9/14/09, online at http://www.usgs.gov/newsroom/article.asp?ID=2305&from=rss_home#.VDU77Ra_4_t.