Widespread “forever chemicals” in drinking water may be linked to increased cancer rates, according to new research analyzing nationwide data on cancer incidence and water contamination.

Scientists at the University of Southern California’s Keck School of Medicine have mapped out potential connections between cancer rates and per- and polyfluoroalkyl substances (PFAS) contamination in drinking water across the United States, revealing patterns suggesting these persistent chemicals may be more dangerous than previously understood.

Forever Chemicals and Cancer Patterns

The recent study, published in the Journal of Exposure Science & Environmental Epidemiology on Jan. 9, identified associations between PFAS in drinking water and increased cancer rates across various organ systems in the United States from 2016 to 2021.

PFAS are a group of manmade chemicals resistant to heat, water, and oil that persist in the environment.

These chemicals can have a range of biological effects, including immune system disruption and altered thyroid function, thus posing potential risks to human and environmental health.

Researchers estimated that PFAS contribute to thousands of incident cancer cases each year, raising concerns over the health risks associated with these “forever chemicals.”

According to the research, PFAS exposure is estimated to contribute to at least 6,800 cancer cases annually in the United States.

Data from the Centers for Disease Control and Prevention show a little more than 1.77 million cancers are diagnosed every year; therefore, currently, about 0.38 percent of yearly cancer cases are linked to PFAS exposure.

“These findings allow us to draw an initial conclusion about the link between certain rare cancers and PFAS,” first author Shiwen (Sherlock) Li, a postdoctoral researcher in the Department of Population and Public Health Sciences at the Keck School of Medicine, said in a press statement.

“This suggests that it’s worth researching each of these links in a more individualized and precise way,” he added.

PFAS Contamination and Cancer Incidence

The study found associations between PFAS in drinking water and increased cancer incidence in multiple organ systems, including digestive, endocrine, oral cavity or pharynx, and respiratory systems.

“The strongest association was observed between PFBS and oral cavity/pharynx cancers,” the authors noted. PFBS (perfluorobutanesulfonic acid) is a type of PFAS found in some food packaging, firefighting foams, and certain industrial processes.

To understand how PFAS contamination relates to cancer incidence, the researchers compared two comprehensive datasets: one from the National Cancer Institute encompassing all reported cancer cases and the other detailing PFAS levels in drinking water nationwide.

PFAS exposure was linked to cancers affecting the urinary system, brain, immune system, and soft tissues among males. In contrast, in females, the incidence of cancer was associated with the thyroid, oral cavity or pharynx, and soft tissue.

Research suggests this link between PFAS exposure and cancer in men, particularly testicular and kidney cancers, is due to PFAS acting as endocrine disruptors, potentially altering hormone balance and affecting cell development.

In women, PFAS chemicals are suspected to disrupt the endocrine system’s hormone function and potentially increase the risk of hormone-related cancers like breast and ovarian.

Call for Further Research

The ecological study emphasizes a need for continued research aimed at mitigating cancer risks associated with PFAS exposure through drinking water.​

The findings align with recent regulatory actions by the U.S. Environmental Protection Agency to control PFAS levels in public water systems, highlighting the importance of environmental health monitoring and intervention.

“When people hear that PFAS is associated with cancer, it’s hard to know how it’s relevant. By calculating the number of attributable cancer cases, we’re able to estimate how many people may be affected,” Li stated, thereby inferring the personal and financial toll of these cases year after year.