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Just When You Thought It Was Safe to Go Back in the Water

Endocrine disruptors. They are the chemicals often found in pesticides and plasticizers (and detergents, food, toys, and cosmetics) that have been known to interfere with reproductive and immune function in both humans and wildlife.

And now a new report highlights their prevalence in the Potomac River system–the primary source of drinking water for the Washington, D.C. metro area.

The report, released today by the Potomac Conservancy, highlights the increased number of intersex fish–male fish that have developed eggs–in the Potomac River watershed.

This peculiar and somewhat terrifying condition has been linked to increased amounts of endocrine disruptors flowing into rivers. The chemical compounds find their way downstream through pharmaceuticals flushed down the toilet, personal care products such as sunscreen, and pesticides that run off lawns and agricultural lands when it rains.

The U.S. Geological Survey (USGS) started to detect this chemicals in rivers throughout the U.S. nearly ten years ago, and then in 2003 intersex fish were collected from several Potomac River sites.

In September 2009, the USGS reported that intersex fish are widespread in numerous river basins throughout the United States.

“Every week new information is coming out about this,” said Anne Sundermann, senior director of communications and outreach for the Potomac Conservancy.

While D.C.’s drinking water still meets the U.S. Environmental Protection Agency’s (EPA) standards, the Conservancy argues that these water quality requirements are outdated, not accounting for endocrine disruptors. In addition, the Conservancy points out that wastewater treatment plants, which dump treated water back into rivers such as the Potomac, were mostly designed and built before the need to remove synthetic substances.

As nonprofits and federal agencies hash out potential new regulations, consumers can do their part by never flushing unused drugs down the toilet and finding sunscreens, perfumes, and other cosmetics with natural ingredients, avoiding harmful chemicals and anti-microbials.


Tasha Eichenseher is the Environment Producer and Editor for National Geographic Digital Media. She has covered water issues for a wide range of media outlets, including E,The Environmental MagazineEnvironmental Science & Technology online newsGreenwireGreen Guide, and National Geographic News.

[This post has been reformatted for Water Currents.]


  1. Ann Smith
    February 1, 2010, 4:06 pm

    I thought this was very intriguing, and I noticed that this issue is prevalent not only in the Potomac River, but also around the world. Marine life is threatened by human activity and pollution in Lake Chivero , Africa , where the waste and free flowing raw sewage flows from two major rivers which are lined with businesses. This sewage threatens not only human drinking water, but also aquatic life because of the potential threat of hyacinth, a nasty water weed which can damage the marine life. Also in 1964 when over 5 million fish in the Mississippi River died because of massive amounts of pesticides. Or how today in China, the Yellow River which is lined with 3,800 chemical factories which pollute it greatly. It’s kind of crazy and sad how we let things get so far that they damage wildlife, like these fish in the Potomac or fish in Lake Chivero. I believe that for all of these, pesticides and pollution should be more regulated.