A groundbreaking study by the U.S. Geological Survey (USGS) has revealed that between 75 and 95 million Americans—more than 20% of the continental United States population—may be consuming drinking water contaminated with per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals."
The research, published October 24 in Science Advances, provides the most comprehensive assessment to date of PFAS contamination in U.S. groundwater used for drinking water supplies, highlighting a significant public health concern that spans across multiple states.
"This study's findings indicate widespread PFAS contamination in groundwater that is used for public and private drinking water supplies in the U.S.," said lead investigator Andrea Tokranov, a USGS research hydrologist.
Widespread Contamination Mapped Across the Nation
Researchers tested over 1,200 groundwater samples for 24 common types of PFAS chemicals. The most frequently detected compounds were perfluorobutane sulfonate (PFBS), perfluorooctane sulfonate (PFOS), and perfluorooctanoate (PFOA).
Using these findings, the team developed a detailed machine-learning model to identify geographic areas with higher contamination likelihood and combined this with existing USGS data on groundwater-dependent populations to establish exposure estimates.
The study revealed significant regional variations in potential exposure:
- Florida and California have the highest number of residents relying on potentially contaminated public water supplies
- Michigan, Florida, North Carolina, Pennsylvania, New York, and Ohio have the most people whose private wells could be contaminated
- In Massachusetts, 86-98% of residents on public water supplies could be exposed to PFAS from groundwater
- In Connecticut, 67-87% of private well users likely have PFAS-contaminated drinking water
To help residents assess their risk, the USGS has created an interactive online map where people can check the probability of groundwater contamination in their area.
"This new predictive model can help prioritize areas for future sampling to help ensure people aren't unknowingly drinking contaminated water," Tokranov explained. "This is especially important for private well users, who may not have information on water quality in their region and may not have the same access to testing and treatment that public water suppliers do."
Global Presence and Potential Solutions
The USGS findings align with a separate international study that detected PFAS chemicals in drinking water samples from 15 countries, affecting both tap and bottled water. That research, published October 17 in ACS ES&T Water, found PFOA and PFOS in more than 99% of bottled water samples tested.
However, the international study also offered some practical solutions, finding that carbon filtration or boiling water can reduce PFAS levels by 50-90%.
"Our findings highlight the widespread presence of PFAS in drinking water and the effectiveness of simple treatment methods to reduce their levels," said Stuart Harrad, professor of environmental chemistry at the University of Birmingham and researcher on the international study. "Either using a simple water filtration jug or boiling the water removes a substantial proportion of these substances."
Health Concerns and Regulatory Response
PFAS compounds have been used in consumer products since the 1940s, including fire extinguishing foam, nonstick cookware, food wrappers, and various industrial processes. Their strong carbon-fluorine bonds make them extremely persistent in the environment and difficult to break down, earning them the "forever chemicals" designation.
Health concerns associated with PFAS exposure include:
- Lowered immune response to vaccination
- Impaired liver function
- Decreased birth weight
- Increased risk of certain cancers
In response to these concerns, the U.S. Environmental Protection Agency has established maximum contamination levels for six types of PFAS in drinking water.
Implications for Public Health Policy
The scale of contamination revealed by these studies underscores the need for comprehensive monitoring and mitigation strategies, particularly for private well users who lack the testing and treatment resources available to public water systems.
Yi Zheng, associate dean of environmental science and engineering at the Southern University of Science and Technology in China, emphasized the importance of consumer awareness: "Increased awareness about the presence of PFAS in both tap and bottled water can lead to more informed choices by consumers, encouraging the use of water purification methods."
As research continues to reveal the extent of PFAS contamination, public health officials face mounting pressure to develop effective strategies for monitoring, regulating, and removing these persistent chemicals from drinking water supplies across the nation.
