A research team that analyzed California tap water during a five-year period concluded contaminants in the water could cause more than 200 cases of cancer each year.
The team, led by Environmental Working Group senior scientist Tasha Stoiber, led a comprehensive study of the California water supply to understand the effects of real-life exposure to potentially harmful contaminants.
The study, published Tuesday in Environmental Health, estimated the number of cancer cases that could be attributed to California tap water between 2011 and 2015.
Researchers observed carcinogenic contaminants, including arsenic, in 2,700 waterways across the state. They estimated that the combined effects of the contaminants may cause about 221 cancer cases per year.
The study showed that even California waterways that meet the legal standards for contaminants pose health risks to residents. It also found that small communities had the highest exposure to waterborne contaminants.