Researchers from the Environmental Working Group stated that the contaminants found in public water systems in California could add 15,500 cancer cases over the course of a lifetime. These contaminants that were identified include chemicals such as hexavalent chromium, arsenic and radioactive elements such as radium and uranium. This study was released Tuesday in the journal Environmental Health.
"We need to look at contaminants as a group -- not just one at a time. It's more important to analyze co-occurring contaminants to understand the real world exposure," said lead author Tasha Stoiber, a senior scientist with EWG.
Stoiber and the other researchers evaluated 2,737 different public water systems that are found across California. They assessed the level of contaminants in the systems. The water systems are the main providers of drinking water in the state, and they serve 98% of California's population. These water systems are regulated by the federal Safe Drinking Water Act and are overseen by state regulators.
The water systems test for both unregulated and regulated contaminants to maintain a safe drinking water supply. The authors of the study estimated cancer risk by studying the reported contaminant levels from the years 2011 to 2015. They also assessed the yearly averages of all the contaminants that were reported and they added all of them together to record the cumulative risk.
The authors of the study divided the water systems into four categories of risk. The highest one estimated cancer risk of more than 1 in 10,000 people being diagnosed with cancer over the course of their lifetime just by drinking California's tap water. They did not identify which of the water systems were considered as high risk.
According to the American Cancer Society, about 40% of Americans will be diagnosed with cancer regardless of the role of water. Around 500 of the water systems in the community were evaluated to fit the high-risk category. The researchers estimated that drinking water from the systems over a lifetime would result in around 4,860 cancer cases.
In addition, the study also stated that the cancer risk was driven by arsenic contamination. The water systems that were said to carry arsenic were the smalled ones in the state, serving just 10,000 residents and they relied on groundwater.
The California Environmental Protection Agency was asked about the report but they said they will not comment on the issue at this time.
