Arsenic Water Contamination Could Lead to More Than 40,000 U.S. Cancer Cases: Study

Researchers indicate that existing technology can already filter out multiple contaminants at once, including arsenic and chromium-6.

New research suggests that tens of thousands of Americans could avoid life-threatening cancers if water systems used currently available filtration methods, which remove multiple contaminants at once.

In the U.S., municipal water systems commonly target only one pollutant at a time, despite the presence of multiple contaminants in many cases. However, many of these pollutants could be addressed with the same treatment methods.

According to findings published in the journal Environmental Research on June 25, using more advanced methods to filter out drinking water contaminants could help reduce exposure to cancer-causing chemicals, including arsenic and chromium-6.

Arsenic, Lead and Chromium-6 Drinking Water Risks

Arsenic is a widespread contaminant in U.S. drinking water, found in every state. It can enter water supplies through natural deposits in the earth, industrial runoff and agricultural pesticide use. 

While organic arsenic tends to pass through the body, inorganic arsenic is highly toxic and has been linked to bladder, lung and skin cancers, as well as heart disease. In California, it is believed to be responsible for the majority of water-related cancer cases that could be prevented through improved filtration.

Chromium-6 is another common drinking water contaminant, with recent estimates suggesting that more than 250 million Americans may be exposed. Studies have connected long-term exposure to increased risks of stomach cancer, liver damage and reproductive health problems. Despite the growing evidence, the U.S. Environmental Protection Agency has not established a federal limit for chromium-6 in drinking water.

Lead exposure through tap water also remains a major concern, particularly in older cities with outdated plumbing systems. The Natural Resources Defense Council estimates that 15 to 22 million Americans are served by water systems with excessive lead levels. 

Even at low concentrations, lead can cause serious health effects, including kidney damage, high blood pressure and cognitive impairments, especially in children. Many of these risks occur at levels still deemed acceptable under current EPA standards.

Cancer Cases Could Be Prevented With Broader Water Filtration

Researchers from the Environmental Working Group analyzed water testing data from more than 17,000 U.S. community water systems collected between 2011 and 2023. The study focused on arsenic and hexavalent chromium (chromium-6), two well-documented carcinogens that are frequently found together in public drinking water supplies.

Although both contaminants can be removed using the same treatment technologies, such as ion exchange and reverse osmosis, most municipal systems continue to target only one pollutant at a time. 

The researchers estimate that addressing both chemicals simultaneously could prevent over 43,000 cancer cases linked to arsenic exposure and another 7,400 cases tied to chromium-6.

The study also found that aligning arsenic limits with those proposed for chromium-6 would quadruple the number of lifetime cancer cases avoided. 

Researchers concluded that removing multiple contaminants at once offers significantly greater public health benefits than addressing them individually, using filtration methods that are already widely available today.

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