Group Finds Carcinogen In 31 Cities' Tap Water

The Environmental Working Group (EWG) says a study it commissioned has detected hexavalent chromium -- a carcinogen -- in tap water from 31 of 35 American cities.

The highest levels were in Norman, Okla.; Honolulu, Hawaii and Riverside, Calif.

In all, water samples from 25 cities contained the toxic metal at concentrations above the safe maximum recently proposed by California regulators, according to the group.

Cancer-causer

The National Toxicology Program has concluded that hexavalent chromium, also called chromium-6, in drinking water shows "clear evidence of carcinogenic activity" in laboratory animals, increasing the risk of gastrointestinal tumors. The chemical compound is linked to increased risk of lung cancer by those who inhale it.

In September 2010, a draft toxicological review by the U.S. Environmental Protection Agency (EPA) similarly found that hexavalent chromium in tap water is "likely to be carcinogenic to humans."

In 2009, California officials proposed setting a "public health goal" for hexavalent chromium in drinking water of 0.06 parts per billion (ppb) to reduce cancer risk. This was the first step toward establishing a statewide enforceable limit.

No test requirements

"Despite mounting evidence of its toxic effects, the EPA has not set a legal limit for hexavalent chromium in tap water nationally and does not require water utilities to test for it," EWG said in a statement on its website.

In 25 cities where EWG's testing detected chromium-6, the group said it was found in concentrations exceeding California's proposed maximum, in one case at a level more than 200 times higher.

According to the environmental group, at least 74 million Americans in 42 states drink chromium-polluted tap water, much of it likely in the cancer-causing hexavalent form.

EPA challenged

"Given the scope of exposure and the magnitude of the potential risk, EWG believes the EPA should move expeditiously to establish a legal limit for chromium-6 and require public water suppliers to test for it," the group said.

The EPA has set a legal limit in tap water for total chromium of 100 ppb to protect against "allergic dermatitis" (skin irritation or reactions). Measures of total chromium include the essential mineral trivalent chromium, which regulates glucose metabolism, as well as the cancer-causing hexavalent form.

Preliminary EWG-commissioned water tests found that in most cases, the majority of the total chromium in water was in the hexavalent form, yet the EPA's legal limit for total chromium is 1,700 times higher than California's proposed public health goal for hexavalent chromium.

"This disparity could indicate significant cancer risk for communities drinking chromium-tainted tap water," EWG said.

The plight of the cancer-stricken residents of Hinkley, Calif., who in 1996 won a $333 million settlement from Pacific Gas and Electric Co. for contaminating their tap water with hexavalent chromium, was the basis of the 2000 movie "Erin Brockovich," starring Julia Roberts.