PFAS are synthetic chemicals found in many products and have accumulated in the environment due to their resistance to breaking down. Drinking water is a significant source of PFAS exposure.
A recent study shows that PFAS is in at least 45% of drinking water near urban areas and is a potential source in the US. These chemicals are linked to various cancers, and assessing their presence in drinking water can help with biomonitoring and prevention efforts.
A new study from the Keck School of Medicine of USC is the first to examine the link between PFAS contamination in drinking water and cancer rates in the US. It found that communities exposed to PFAS-contaminated drinking water have up to a 33% higher incidence of certain cancers.
Researchers conducted an ecological study using large population datasets to understand PFAS and cancer risk. Between 2016 and 2021, US counties with PFAS-contaminated drinking water had higher cancer rates, differing by sex.
PFAS in drinking water is estimated to cause over 6,800 cancer cases each year, based on recent data from the US Environmental Protection Agency (EPA).
Shiwen (Sherlock) Li, PhD, a postdoctoral researcher in the Department of Population and Public Health Sciences at the Keck School of Medicine and the study’s first author, said, “These findings allow us to draw an initial conclusion about the link between certain rare cancers and PFAS. This suggests that it’s worth researching each of these links in a more individualized and precise way.”
To understand how PFAS contamination relates to cancer, researchers compared two large datasets: one for all reported cancer cases and one for PFAS levels in drinking water across the US. They used data from 2016 to 2021 for cancer cases and from 2013 to 2024 for PFAS levels.
The researchers controlled for age, sex, socioeconomic status, smoking rates, obesity, urbanicity, and other pollutants. They compared cancer rates in each county to PFAS levels in drinking water, using the EPA’s recommended cutoffs for each type of PFAS.
Counties with PFAS levels above the recommended maximum had higher rates of digestive, endocrine, respiratory, and mouth and throat cancers. The increase in cancer incidence ranged from 2% to 33%, with the highest increase linked to perfluorobutanesulfonic acid (PFBS).
In counties with PFAS-contaminated drinking water, males had higher rates of leukemia, urinary system, brain, and soft tissue cancers compared to those in areas with uncontaminated water. Females had higher rates of thyroid, mouth, and throat, and soft tissue cancers. According to recent EPA data, PFAS contamination is estimated to cause 6,864 cancer cases per year.
Li explained that calculating the number of cancer cases linked to PFAS helps estimate the impact on people and the financial toll. These findings reveal associations between PFAS and rare cancers that might otherwise be missed. Individual-level studies are needed to determine if the link is causal and to explore the biological mechanisms involved.
The results also suggest that PFAS levels should be limited, and proposed regulations might not go far enough. Less-studied PFAS need more monitoring, and regulators should consider other PFAS that may not be strictly regulated yet.
Journal Reference:
- Li, S., Oliva, P., Zhang, L. et al. Associations between per-and polyfluoroalkyl substances (PFAS) and county-level cancer incidence between 2016 and 2021 and incident cancer burden attributable to PFAS in drinking water in the United States. J Expo Sci Environ Epidemiol (2025). DOI: 10.1038/s41370-024-00742-2
Source: Tech Explorist