U.S. water utilities have known about the prevalence of a likely carcinogen in water sources for seven years and have failed to share that information with the public, according to an advocacy group, which released today a 2004 industry study of hexavalent chromium.

The American Water Works Association (AWWA) Research Foundation study focused on hexavalent chromium in groundwater sources nationwide. The AWWA report was obtained and released by the nonprofit Environmental Working Group today.

The 124-page report features data from tests on 341 water samples from 189 water utilities in 41 states. About two-thirds of those samples came from groundwater sources, while another third came from surface sources. The report found hexavalent chromium nationwide, particularly in groundwater. The highest levels were found in California.

"Several groundwater results show total chromium concentrations composed exclusively by hexavalent chromium," the report says. "This speciation trend has not been previously reported."

The study emphasizes that the "majority of the hexavalent chromium results were found to be less than" the current U.S. EPA Method Detection Limit (MDL). But it also concluded that conventional filtering systems used by water utilities in 2004 were typically ineffective in addressing hexavalent chromium.

"In the case of conventional treatment systems," the report states, "hexavalent chromium is not removed."

Hexavalent chromium, also known as chromium-6, is best known as the subject of activist Erin Brockovich's crusade against Pacific Gas and Electric Co. in Hinkley, Calif., which resulted in a 1996 settlement of $333 million. Brockovich's fight was the subject of a 2000 feature film, "Erin Brockovich," which starred Julia Roberts.

In a statement on the AWWA report, Brockovich accused water utilities of shielding important information from the public. "I'd like to say I'm surprised at the utilities' silence, but I'm not," she said. "Instead of treating their customers like adults and sharing the test results with them, they shelved the findings, letting folks continue to drink water for years that could contain chromium-6."

The AWWA did not return multiple calls seeking comment on the study.

The report comes as there has been an increased focus on hexavalent chromium among green groups. The Environmental Working Group released a study last December that found elevated levels of the chemical in the drinking water of 25 of the 35 U.S. cities it tested (Greenwire, Dec. 20, 2010).

Rebecca Sutton, a chemist at the group and the author of the December report, said the chemical has long been considered a carcinogen when inhaled, but new testing methods and an increased focus on it has led to recent discoveries about its health effects in drinking water.

"What's really changed is our level of knowledge and concern about this chemical in drinking water," Sutton said.

EPA review

Last September, U.S. EPA issued a draft review that said hexavalent chromium in tap water was "likely carcinogenic to humans." That assessment relied on the results of a 2008 National Toxicology Program (NTP) study that found higher occurrence of gastrointestinal tumors in rodents exposed to the substance.

The agency is currently conducting a formal review of the chemical, which could lead to new drinking water standards. EPA has said it hopes that assessment will conclude this year.

California has already sought to address hexavalent chromium in its drinking water, lowering the drinking water standard for the chemical from 0.06 parts per billion to 0.02 ppb this January (Greenwire, Jan. 3).

AWWA and the American Chemistry Council have both questioned the results of the 2008 NTP study, arguing against the application of the findings to human exposures at lower levels. Both industry groups have also pressed EPA to delay its formal toxicology assessment until new studies are conducted this year.

The Water Research Foundation -- an offshoot of the AWWA -- announced last week that it is sponsoring two programs to address hexavalent chromium. The first is a pilot program in Glendale, Calif., that will examine technologies for reducing the levels of the substance in drinking water. The second is a broad study on the occurrence of the chemical in drinking water and its health effects.

"There is a great deal of interest in chromium-6 from government agencies, public health advocates, the utility industry and the general public -- making it imperative to have solid information to help make sound decisions," Robert Renner, the foundation's executive director, said in a statement.

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