By Vivian Ho in San Francisco
Drinking California tap water over the course of a lifetime could increase the risk of cancer, according to a study published Tuesday.
Researchers with the Environmental Working Group, an advocacy nonprofit, studied the combined health impacts of contaminants found in 2,737 community water systems throughout California and calculated that prolonged consumption of the contaminated water could cause almost 15,500 new cases of cancer.
The study found traces of arsenic, hexavalent chromium, and disinfection byproducts in the water systems. All of these contaminants are regulated federally and on a state level. Trace amounts of some arelegally allowed in the water.
But the study found that a majority of the cancer risk was due to the cumulative effect of these legally allowed amounts. “A large majority of the cancer risk, about 85% of it, is due to the combination of contaminants that are present at legal limits,” explained Tasha Stoiber, an Environmental Working Group senior scientist and the lead author of the report.
“We have found that the majority of that risk was below the federal legal standard,” she told the Guardian. “These cumulative risks are based on health-based standards, not legally enforceable levels. So although the drinking water may get a passing grade, there still may be some health risks associated with it.”
The California Environmental Protection Agency said it was reviewing the study. “Assessing the cumulative risks from multiple contaminants is very complicated and there is no general consensus on the best way to do it,” said Sam Delson, a spokesman with the state Office of Environmental Health Hazard Assessment.