In an investigation by the Associated Press, drinking water supplies in 24 major metropolitan areas were found to include drugs.
According to the investigation, the drugs get into the drinking water supply through several routes: some people flush unneeded medication down toilets; other medicine gets into the water supply after people take medication, absorb some, and pass the rest out in urine or feces. Some pharmaceuticals remain even after wastewater treatments and cleansing by water treatment plants, the investigation showed.
Although levels are low -- reportedly measured in parts per billion or trillion -- and utility companies contend the water is safe, experts from private organizations and the government say they can't say for sure whether the levels of drugs in drinking water are low enough to discount harmful health effects.
WebMD asked experts to give their take on the potential risks of drugs in the water supply.
Is this a new phenomenon, the finding of pharmaceuticals in public water supplies?
No. Low levels of pharmaceuticals in the water supply have been a concern for a decade or longer, says Sarah Janssen, MD, PHD, MPH, a science fellow at the Natural Resources Defense Council, an environmental action group.
"Ever since the late 1990s, the science community has recognized that pharmaceuticals, especially oral contraceptives, are found in sewage water and are potentially contaminating drinking water," Janssen tells WebMD.
Concern among scientists increased when fish in the Potomac River and elsewhere were found to have both male and female characteristics when exposed to estrogen-like substances, she says. For instance, some fish had both testes and an ovary, she says.
Scientists starting looking at the effects of oral contraceptives first, she says. "Now analyses have expanded to look at other drugs," Janssen says.
Technology has made this research easier, says Suzanne Rudzinski, deputy director for science and technology in the Office of Water at the U.S. Environmental Protection Agency. "Analytical methods have gotten better and we are able to detect lower levels than ever before."