Probable carcinogen found in US drinking water

The New York Times | December 21, 2010
By John Collins Rudolf

Low levels of hexavalent chromium, an industrial chemical used in the production of stainless steel and chrome plating, have been found in drinking water supplies across the United States, a new study by an environmental group has found.

Those who saw the 2000 film “Erin Brockovich” will remember hexavalent chromium, also known as chromium-6, as the chemical spreading in a plume beneath the town of Hinkley, Calif., from a disposal site run by Pacific Gas & Electric. The company ultimately paid $333 million in damages for the contamination after a class-action lawsuit.

The chemical has been linked to increased cancer risk. But Allan Smith, a professor of epidemiology at the School of Public Health at the University of California, Berkeley, said the concentrations reported by the Environmental Working Group were probably no cause for concern.

“The public should not be alarmed by the very small concentrations being reported for most cities,” Dr. Smith wrote in an e-mail message.

Other experts disagreed. Max Costa, chairman of the department of environmental medicine at New York University’s School of Medicine, told The Washington Post that the levels of the chemical were “disturbing” and said that states should strive to eliminate the presence of the chemical from water entirely.

California regulators have proposed a “public health goal” that would limit hexavalent chromium to just .06 parts per billion in drinking water, but industry groups call that level unrealistically low. The Environmental Protection Agency is studying whether to introduce a national drinking water standard for the chemical.

California’s proposed health goal is designed to limit possible cancer risk to just 1 in a million for those exposed to hexavalent chromium. Drinking water standards have far higher thresholds for known carcinogens, however: the federal standard for arsenic, for instance, is set at 10 parts per billion.

“Raising alarm that chromium in water might be above a “public health goal” is unfortunate,” Dr. Smith wrote. “It diverts energy and resources from more important public health concerns.”

“For example, large numbers of private wells in the U.S. contain arsenic at much higher concentrations than the above drinking water standard,” he wrote. “But it seems nobody cares.”