Is water supply drugged?

Residues of birth control pills, antidepressants, painkillers, shampoos and a host of other compounds are finding their way into the nation's waterways, and they have public health and environmental officials in a regulatory quandary.

On the one hand, there is no evidence the traces of the chemicals found so far are harmful to human beings. On the other hand, it would seem cavalier to ignore them.

The pharmaceutical and personal care products, or PPCPs, are being flushed into the nation's rivers from sewage treatment plants or leaching into groundwater from septic systems. According to the Environmental Protection Agency, researchers have found these substances, called "emerging contaminants," almost everywhere they have looked for them.

Most experts say their discovery reflects better sensing technology as much as anything else. Still, as Hal Zenick of the agency's office of research and development put it in an e-mail message, "there is uncertainty as to the risk to humans."

In many cases, the compounds enter the water when people excrete them or wash them away in the shower. But some are flushed or washed down the drain when people discard outdated or unused drugs.

In a survey begun in 1999, the U.S. Geological Survey tested 139 streams around the country and found that 80 percent of samples contained residues of drugs like painkillers, hormones, blood pressure medicines or antibiotics.

But Christopher Daughton, a scientist at the Environmental Protection Agency and one of the first scientists to draw attention to the issue, said PPCP concentrations in municipal water supplies were lower than they were in water generally because treatments like chlorination and filtration with activated charcoal alter or remove many chemicals.

Researchers suspect that the volume of PPCPs excreted into the nation's surface water and groundwater is increasing. For one thing, per capita drug use is on the rise, not only with the introduction of new drugs but also with the use of existing drugs for new purposes and among new or expanding groups of patients, like children and aging baby boomers.

Also, more localities are introducing treated sewage into drinking water supplies. Researchers who have studied the issue say there is no sign that pharmaceutical residues accumulate as water is recycled. On the other hand, the FDA said in its review, many contaminants "survive wastewater treatment and biodegradation and can be detected at low levels in the environment."