"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 milligrams per liter, from the previous level of 50 milligrams. 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."