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Toxic contaminants found in California’s tap water could cause cancer

A new study from the Environmental Working Group (EWG) has revealed that toxic pollutants in California’s drinking water could cause more than 15,000 cases of cancer. The research is the first of its kind to investigate the risk associated with all of the contaminants in the state’s public water systems collectively.

For their study, the EWG scientists used a new analytical technique to quantify the combined health impacts of carcinogens and other toxic contaminants in more than 2,700 community water systems across California.

“This cumulative approach is common in assessing the health impacts of exposure to air pollutants but has never before been applied to drinking water contaminants,” said study lead author Dr. Tasha Stoiber. “Right now, policymakers set health limits one chemical at a time. This doesn’t match reality. Multiple contaminants are often detected in drinking water across the U.S.”

According to the researchers, the lifetime cumulative cancer risk that has been projected for California should be considered conservative. This is because contaminants can become even more toxic when they are mixed together compared to the estimated potency from individual chemicals.

“This could and should be a big deal,” said EWG senior science advisor Dr. Olga Naidenko. “We need to prioritize the treatment of our tap water. This novel approach to risk assessment offers a significant improvement over the current model and, if adopted, will be a huge step toward improving public health. It will help communities and policymakers evaluate the best options to treat drinking water.”

The water systems that posed the highest cancer risk were found to be those that serve smaller communities with fewer than 1,000 people, where there is an increased exposure to arsenic. In order to provide safer drinking water to residents, these communities are in need of improved infrastructure.

The study is published in the journal Environmental Health.

By Chrissy Sexton, Staff Writer

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