Water contents hard to swallow?

Water contents hard to swallow?

The oil spill now creeping down the Ohio River provides an unpalatable lesson in how vulnerable the U.S. water supply is to pollutants. But even "normal" tapwater can contain organic contaminants from oil leakages and industrial wastes, according to a new report.

In the most comprehensive compilation of water-quality surveys undertaken since the passage of the Safe Drinking Water Act in 1974, the Center for Study of Responsive Law reported last week that some 2,100 compounds, mostly organic, have been detected in U.S. drinking water. Of these, about 190 are known or suspected to be dangerous, says the Center, and the health effects of the rest have not been adequately studied. The Washington, D.C.-based public interest group also found that 19 percent of the 18,157 water systems tested to date for unregulated compounds are contaminated by at least one organic chemical.

The ability to eradicate cholera and other water-borne diseases that killed thousands last century "has lulled [U.S.] regulatory authorities and the public alike into a false sense of well-being regarding [this century's] growing threat of toxic organic chemicals," write Duff Conacher and his colleagues.

The analysts charge that the Environmental Protection Agency (EPA) has not exercised its full authority under the water act. They say the agency should require local monitoring of a wider range of pollutants, since the lack of such data has stalled health-effect studies needed for setting standards.

The group also argues that EPA should require some local water authorities to use treatments, such as granular activated carbon (GAC), that remove toxic organic chemicals much more effectively than standard techniques. According to Conacher, only 50 of the 60,000 public systems use the improved treatments.

Larry J. Jensen, EPA's assistant administrator for water, asserts that EPA has scrutinized the organics data and has developed "a very deliberate strategy [to regulate] those chemicals of greatest concern to human health." Jensen argues that most of the Center's 2,100 compounds occur naturally and that the 190 potentially dangerous chemicals are typically detected at insignificant levels. And while GAC is effective, he says, it is not a panacea; for example, it cannot remove vinyl chloride, one of the most toxic and ubiquitous organics.