More than 80% of the male bass fish in Washington's major river are now exhibiting female traits such as egg production because of a "toxic stew" of pollutants, scientists and campaigners reported yesterday.
Intersex fish probably result from drugs, such as the contraceptive pill, and other chemicals being flushed into the water and have been found right across the US.
But she said early evidence pointed to a mix of chemicals – commonly used at home as well as those used in large-scale farming operations – causing the deformities. The suspect chemicals mimic natural hormones and disrupt the endocrine system, with young fish being particularly susceptible.
The chemicals could include birth control pills and other drugs, toiletries especially those with fragrances, products such as tissues treated with antibacterial agents, or goods treated with flame retardants that find their way into waste water. However, Blazer also pointed to runoff from fertilisers and pesticides from agricultural areas.
About 5 million people live in the greater Washington area, and 90% of them get their drinking water from the Potomac.