LOS ANGELES - The head of the U.S. Environmental Protection Agency said yesterday it was likely to tighten drinking water standards to address potential health risks of a carcinogen detected in the tap water of 31 cities across the country.

EPA Administrator Lisa P. Jackson said she was concerned about the prevalence of the chemical hexavalent chromium, also known as chromium 6.

The Environmental Working Group released a study Monday that analyzed drinking water across the country and found the highest levels of chromium 6 in Norman, Okla.; Honolulu; Riverside, Calif.; Madison, Wis.; and San Jose, Calif.

Sens. Barbara Boxer and Dianne Feinstein said the EPA's chromium standard is outdated because it was set nearly two decades ago, the letter said.

Jackson detailed a series of actions to be taken by the EPA, including working with state and local officials and issuing guidance to all water systems on testing for the carcinogen. - AP

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