The Environmental Protection Agency’s revised rule on arsenic contamination in drinking water has resulted in fewer lung, bladder and skin cancers.
In 2006, the E.P.A. reduced the arsenic maximum in public water systems to 10 micrograms per liter, from the previous level of 50 micrograms. The rule does not apply to private wells.
Using data from a continuing nationwide health survey, researchers compared urinary arsenic levels in 2003, before the new rule went into effect, with those in 2014, after it had been fully implemented. There were 14,127 participants in the study, and the scientists adjusted for arsenic contributions from tobacco and dietary sources. The report is in Lancet Public Health.
They found a 17 percent reduction in arsenic levels among those using public water systems. The researchers estimate that the new rule resulted in 200 to 900 fewer lung and bladder cancers and 50 fewer skin cancers annually.
The senior author, Dr. Ana Navas-Acien, a professor of environmental health sciences at the Columbia University Mailman School of Public Health, said that water treatment to remove arsenic is expensive and a challenge for smaller cities.
“We are trying to provide information in a way that’s useful for policymakers,” she said. “If we could eliminate arsenic entirely, it would be ideal. But we have to be realistic.”
An earlier version of this article misstated the levels of arsenic permitted in public water systems. It is 10 micrograms per liter, not 10 milligrams.