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 P.P.C.P.’s, 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...
