Study Finds Water Treatment for Multiple Contaminants Could Prevent Over 50,000 Cancer Cases in the U.S.

A recent study conducted by the Environmental Working Group highlights the significant potential of comprehensive water treatment strategies that target multiple tap water pollutants simultaneously. This approach could prevent more than 50,000 cancer cases over a lifetime in the United States. Traditionally, regulatory policies have addressed water contaminants one at a time, but this research emphasizes the benefits of a multi-contaminant method.

Analyzing over a decade's worth of data from more than 17,000 community water systems across the country, scientists identified that harmful chemicals such as arsenic and hexavalent chromium (chromium-6) frequently coexist in water supplies. When these contaminants are present together, they pose a compounded health risk, notably increasing the likelihood of developing cancers like stomach and bladder cancer.

The study demonstrates that reducing arsenic levels in water systems that also contain chromium-6 can significantly decrease cancer risk, potentially avoiding quadruple the cases linked solely to chromium-6. This underscores the importance of tackling multiple pollutants concurrently to maximize health benefits.

While treating water for individual contaminants has its advantages, integrating treatment processes to address multiple pollutants at the same time offers a far greater protective effect. This strategy could particularly benefit communities in states like California, Arizona, and Texas, where arsenic pollution is a major concern. In these regions, nearly 80% of preventable cancer cases are related to arsenic exposure.

Chromium-6, a chemical infamously depicted in the film 'Erin Brockovich,' has been linked to serious health problems including stomach and reproductive cancers, liver damage, and other health issues. Although the EPA regulates total chromium, it does not set specific limits for chromium-6, which is considered more hazardous.

Similarly, arsenic, naturally occurring in many water sources due to geological deposits or human activities like mining and pesticide use, is associated with multiple cancers and cardiovascular problems. The current federal arsenic limit (10 ppb) is based on outdated risk assessments; scientists argue that even lower levels pose significant health risks.

Another common contaminant is nitrate, originating from agricultural runoff and septic systems, which has been linked to cancers, birth defects, and health issues such as 'blue baby syndrome.' The existing safety standard for nitrate has not been revised in over 30 years, despite new evidence showing adverse effects at much lower levels.

The study calls for a shift in water regulation policies to consider the combined effects of multiple contaminants rather than addressing each independently. This approach could lead to more effective public health protections, especially for vulnerable or underserved communities that often lack resources for infrastructure upgrades.

Advances in water treatment technologies, such as reverse osmosis and ion exchange systems, can simultaneously remove multiple pollutants. Implementing these solutions broadly could dramatically improve water safety and health outcomes. Additionally, consumers can consider using home water filters—particularly reverse osmosis units—to reduce exposure to harmful chemicals.

Ultimately, comprehensive and integrated water treatment policies are essential for reducing cancer risk and ensuring equitable access to safe drinking water for all communities across the U.S.

Source: https://medicalxpress.com/news/2025-07-multiple-contaminants-cancer-cases.html