PFAS in Drinking Water Linked to Certain Forms of Cancer: Study

Water contamination from toxic “forever chemicals” contributes to several thousand cases of cancer each year, researchers determined.

A group of researchers say they have linked increases in certain types of cancers to the presence of per- and polyfluoroalkyl substances (PFAS) in the nation’s drinking water supply, raising further concerns about the long-term health risks faced by Americans living in areas with known water contamination problems.

Also commonly referred to as “forever chemicals,” PFAS include a group of more than 9,000 man-made substances, which have been used in a wide number of products over the past few decades, including materials that resist grease, oil and water.

High volumes of the chemicals are also found in aqueous film-forming foam (AFFF) used by the military and civilian firefighters to fight fuel-based fires, which has been cited as a major source of PFAS water contamination in the United States.

The chemicals are now known to persist in the environment and build up in the human body, and years of previous research have suggested PFAS exposure can cause a variety of serious health effects, including several types of cancer, ulcerative colitis, disruption of the hormone system and other serious diseases.

Now, researchers from the Keck School of Medicine at the University of Southern California have published findings in the Journal of Exposure Science & Environmental Epidemiology on January 9, which they say shows an association between PFAS in drinking water and increases in cancer at the county level.

The team of researchers, led by Shiwen Li, looked at county-level age-adjusted cancer incidents in the U.S. from 2016 to 2021. They also looked at data on PFAS levels in public drinking water systems from 2013 to 2015 and 2023 to 2024.

According to their findings, the presence of PFAS in drinking water was linked to increased rates of cancer in the digestive, endocrine, oral cavity, pharynx and respiratory systems. The strongest association was with mouth and throat cancers.

The researchers also found that there were some differences in the effects of PFAS exposure based on sex, with males seeing increases in urinary, brain, leukemia and soft tissue cancers, and females seeing increases in thyroid cancer, oral cavity/pharynx and soft tissue cancers. They estimate the PFAS in drinking water contributes to between 4,600 and 6,900 incidents of cancer per year.

“This cancer-wide ecological study presents evidence linking PFAS exposure through drinking water to increased cancer risks,” the researchers concluded. “The significant associations identified between PFAS in drinking water and various cancers, including those of the endocrine, digestive, oral cavity, pharynx, skin, and respiratory systems, underscore the urgent need for more comprehensive research.”

January 2025 PFAS Lawsuits Update

The study comes as chemical and safety equipment manufacturers like 3M Company, DuPont and BASF face thousands of PFAS water contamination lawsuits filed by water providers and individuals diagnosed with various types of cancer, as well as firefighter PFAS injury lawsuits brought by individuals who came into direct contact with the chemicals, and may give even more scientific credence to their claims.

Given common questions of fact and law raised in PFAS exposure lawsuits brought throughout the federal court system, the lawsuits have been consolidated under U.S. District Judge Richard M. Gergel in South Carolina, for coordinated pretrial proceedings as part of an MDL, or multidistrict litigation.

As part of the coordinated management of the litigation, a small group of early PFAS contamination lawsuits are being prepared for trial dates later this year, involving claims that individuals developed testicular cancer, kidney cancer, liver cancer, thyroid cancer, thyroid disease and ulcerative colitis, after drinking water known to be contaminated with high levels of the chemicals.

While the outcome of these early trial dates will not have any binding impact on other claims being pursued throughout the federal court system, they are designed to help gauge how juries may respond to certain evidence and testimony that will be repeated throughout the litigation.