Cause of Intersex Fish, Should We Be Worried?
By Tony Miller, U.S. EPA, Office of Enforcement and Compliance Assurance, Federal Facilities Enforcement Office, Planning, Prevention & Compliance Staff, Email: Miller.Anthony at epa.gov

In 2003, fish in the Potomac Watershed near Washington, D.C., were found to be abnormal. In the West Virginia stream, many fish were mysteriously dying and appearing with lesions. After further inspection, several male smallmouth bass were found to exhibit female characteristics.

In a study taken by the U.S. Geological Survey (USGS), “More than 80% of all the male smallmouth bass they found were growing eggs, including all of the fish caught at four of the seven survey sites” (USGS qtd. in Fahrenthold, 2006). The immediate thought was pollution. Then questions shortly followed, how could this have happened? Why didn’t anyone foresee this? How come no one is doing anything to stop this? Should we be worried that we could be affected? I will try to answer those questions as well as explain the possible causes that professionals have hypothesized, what is planning to be done, and how this issue will come to affect water treatment in the future.

Key Terms

USGS believes that the source of these abnormalities is caused by Endocrine Disrupting Chemicals (EDCs). EDCs are chemicals that imitate the body’s natural hormones which can cause an alteration such as what has been seen in the smallmouth bass. EDCs come from many different places, such as municipal sewage, and can even be useful for other reasons, such as birth control. Another key term is vitellogenin protein. Vitellogenin is “the material that feeds embryos… [and]…only females have the hormone that can initiate vitellogenin production” (Greenwire, 2005).

Early Findings

When a shocking issue arises, neighboring communities need to know which agencies with authority on water contamination, have any knowledge on this issue and what they are doing to prevent any harm to humans. The U.S. Environmental Protection Agency (EPA), which has a governing authority on all pollution issues, is obviously one of the key players in this concern. According to the EDSP Chronology:  

In August 1996, Congress passed both the Food Quality Protection Act (FQPA) and amendments to the Safe Drinking Water Act (SDWA), both containing provisions calling for the screening and testing of chemicals and pesticides for possible endocrine disrupting effects (EPA, 2006).  

Knowledge that FQPA and SDWA were passed almost ten years ago has created much distrust and upset feelings between the EPA and the neighboring communities of the Potomac Watershed. These communities are wondering why the EPA has not done anything sooner. However, the EPA has written up plans for how it will investigate these recent findings. Immediately after the initial fish findings, the USGS testing has found many correlations between different EPA issued water discharge permits and the percentage of intersex fish. The initial study has indicated that “potential sources of EDCs to the river are municipal sewage treatment plant discharges and poultry and cattle feedlots” (EPA, 2005).

Hopeful Solutions  

The EPA released an article discussing how it was going to start on and hopefully solve this problem, now that the possible source has been identified. In order to learn how life in the water is affected, EPA has “developed a quantitative real time (Q-PCR) assay for smallmouth bass to measure the induction of the vitellogenin (VTG) gene in male fish” (EPA, 2005). The method set forth calls for a clone of the VTG gene in order to discover which chemicals are causing this affliction, in addition to developing proper regulations.  

Possible Future Regulations  

EPA will issue regulations, soon after the investigation is completed, for all water treatment plants as well as new water discharge permits, in order to reduce EDCs that are causing this irregularity. When regulations are released, redesigning water treatment plants will be necessary to avoid any violation. Preparation with funds as well as an engineering team, which could readily figure new ways to treat these chemicals, will be essential for the compliance of policies plus the betterment of the neighboring waters.   Optimistically, the studies will show more conclusive evidence of what contaminants need to be eliminated. With these studies, the leading agencies can issue new regulations in order to help reduce these impurities and help return our wildlife to the environment they need to survive and thrive.

Information in this article is drawn from: Fahrenthold, David A. (2006, Sept 6), Male Bass Across Region Found to Be Bearing Eggs; Greenwire. (2005, Aug 8). Hormone abnormalities plague Potomac River fish. EPA. (2006, Mar 29). EDSP Chronology. Retrieved. EPA. (2005, Nov 14). Development of a Smallmouth Bass Quantitative Real-Time Pcr Assay to Measure Vtg Gene Induction in Male Fish from the South Branch of the Potomac River.