California's Contaminated Tap Water Poses Cancer Risk: Study

LOS ANGELES, CA — The toxic brew of pollution in California’s tap water poses an increased risk of cancer for thousands of people across the state, according to a new study out this week.

The Environmental Working Group found that carcinogens and other toxic contaminants found in the community water systems could cause more than 15,000 cases of cancer statewide. Those most at risk get tend to live in small to midsize communities. In many cases, the contaminants found in drinking water supplies fell below the legal limit, but combined together, they increase the risk of cancer, according to the advocacy group’s toxicologists. It’s the first peer-reviewed study to assess the cumulative risk from combined contaminants commonly found in water the Golden State's water supplies.

“Drinking water rarely contains only one contaminant, yet regulators currently assess the health hazards of tap water pollutants one by one,” scientists Tasha Stoiber and Olga Naidenko wrote in presenting their findings. “This ignores the combined effects of multiple pollutants, which is how people ingest them in the real world.”

The study examined 2,700 community water systems and found that residents in many communities are drinking tap water that contains carcinogens and contaminants such as radioactive uranium, chromium-6 and arsenic.

"There's no safe level," Kelly Reynolds, director of the Environment, Exposure Science and Risk Assessment Center at the University of Arizona, told CNN.

Arsenic can be naturally occurring or the result of industrial waste.

Reynolds, who was not involved with the study, said she wasn't surprised that smaller water systems carried higher risks.

"Small utilities tend not to have as advanced treatment capabilities as your larger utilities," she said.

The study examined the reported contaminant levels from 2011 to 2015 and found that:

• About 3.1 million Californians get their tap water from 495 contaminated systems that could cause an estimated 4,860 people to develop cancer..
• Another 28.5 million get their tap water from 1,177 contaminated systems that could cause an estimated 10,427 people to develop cancer.
• Statewide, nearly two-thirds of drinking water systems contained at least two cancer-causing contaminants in excess of one-in-a-million risk levels.

Researchers hope their findings will spur infrastructure improvements to improve water quality, especially in smaller communities that don’t tend to have funds to improve aging water systems.

However, not everyone is pleased with the study. Some are calling it alarmist.

"I have a real concern when an organization puts out an unfounded report that causes alarm to our own customers about the quality of L.A.'s drinking water,” Marty Adams, the COO of the Los Angeles Department of Water and Power said in a statement to ABC7. “This report from EWG is misleading and we want our customers to know that L.A.'s drinking water is safe, of the highest quality, and surpasses all state and federal drinking water standards."

The authors of the study acknowledge that more work needs to be done to better understand the cumulative effects of contaminants in drinking water. In the meantime, they recommend steps residents can take to protect their families.

The EWG Tap Water Database will show you if your drinking water contains contaminants. If harmful contaminants were found in your water, even at levels below the federal legal limits, the EWG recommends using a filtering system. The National Sanitation Foundation compiled a list of certified filter systems.