A 2006 study by the U.S. Geological Survey of fish from the Potomac River and various tributaries found intersex in 80% of male bass examined. All samples — those with and without signs of intersex — contained detectible levels of at least one endocrine-disrupting compound. Also, a recent study showed that chemicals commonly found in personal care products, including fragrances and antimocrobial products, were found in muscle tissue of 100% fish tested. The waters (in Texas) were found to be persistent in the fishes environment because of continuous introduction from a wastwater treatment plant.
Locally, the DC Department of Health urges limited consumption of Anacostia and Potomac river fish because of PCB contamination. PCBs have endocrine disrupting qualities. Click here for full advisory. Always skin the fish, trim away fat, and cook fish to drain away fat because chemical contaminants tend to concentrate in the fat of the fish.
Current Research
A recent study indicates that some of the same pollutants that apparently cause male fish in the Potomac and Shenandoah rivers to exhibit female characteristics (i.e., intersex characteristics) may also leave them vulnerable to disease and large-scale fish kills. The study, from the U.S. Geological Survey researchers injected largemouth bass with estrogen. Those fish were then found to produce lower levels of a hormone called hepcidin that is believed to bolster immune systems. Click here for more information.
Background
In spring 2002, large populations of smallmouth bass and redbreast sunfish were found dead in the South Branch of the Potomac River in West Virginia. Each year since, fish kills of varying severity have occurred in the Potomac River or one of its tributaries.
In 2003, scientists performing necropsies on these fish made a surprising find—many of the dissected male fish contained oocytes (precursors of egg cells normally produced by females) in their testes, a condition known as intersex.
A 2006 study by the U.S. Geological Survey of fish from the Potomac River and various tributaries found intersex in 80% of male bass examined. All samples—those with and without signs of intersex—contained detectible levels of at least one endocrine-disrupting compound.
Endocrine disruptors mimic hormones, and can disturb the body’s normal biological functions. A congressional hearing was held to examine the issue in October 2006, with all participants agreeing that more research was needed to investigate the causes of intersex, the role of endocrine disruptors, and the possible affects of both on human health.
Links:
Public Health Advisory: DC Department of Health urges limited consumption of Anacostia and Potomac river fish.
Widespread occurrence of intersex in black basses (Micropterus spp.) from U.S. rivers, 1995–2004 : Jo Ellen Hinck, Vicki S. Blazer, Christopher J. Schmitt, Diana M. Papoulias, and Donald E. Tillitt; J. Aquatic Toxicology, Volume 95, Issue 1, 19 October 2009, Pages 60-70
Effects of Estrogen and Estrogenic Endocrine-Disrupting Compounds on Fish Immunity: Robertson, LS, Iwanowicz, LR, and Marranca, JM. Identification of centrarchid hepcidins and evidence that 17β-estradiol disrupts constitutive expression of hepcidin-1 and inducible expression of hepcidin-2 in largemouth bass (Micropterus salmoides). Fish & Shellfish Immunology, In Press, Corrected Proof, Available online 17 April 2009.