Use of home water filters linked with lower levels of PFAS in the body

People who live longer in communities with contaminated drinking water also have higher levels of PFAS in their blood, new study finds

For people in areas where the drinking water supply is highly contaminated with PFAS, using a home water filter may help reduce the buildup of these harmful “forever chemicals” in their bodies over time, according to a new study led by Silent Spring Institute.

Reporting in the Journal of Exposure Science & Environmental Epidemiology, researchers found that residents who primarily drank filtered tap water had lower levels of PFAS in their blood than those who drank unfiltered tap water. Similar reductions were seen among people who mainly drank bottled water. The differences were measured years after municipal water systems started treating the water to remove PFAS.

“While installing treatment at public water systems remains the most effective way to protect entire communities, our study shows that people can take steps now to protect themselves while their community works toward a long-term solution,” says lead author, Emily Heckel, a staff scientist at Silent Spring. “This is especially important for communities waiting for treatment systems to come online and for private well owners who are responsible for monitoring their own water quality.”

PFAS are a class of highly persistent chemicals linked to cancer, thyroid disease, high cholesterol, decreased response to vaccines, low birth weight, shorter breastfeeding duration, and many other health problems. They’re used in a wide range of consumer products and in firefighting foams. Because PFAS break down very slowly, they accumulate in the environment and can remain in the body for years.

The new study draws on data from the Massachusetts PFAS and Your Health Study, led by Silent Spring as part of the CDC/ATSDR PFAS Multi-site Study. Researchers collected blood samples and survey data from 673 adults living in Hyannis and Ayer, where the drinking water had been contaminated by firefighting foam used at military and firefighter training sites. Although Hyannis and Ayer now treat their water to remove PFAS, scientists are concerned about the long-term health effects of past exposure.

For about 400 participants, the team documented where they had lived and how long they had lived there, going back to 2000. They also asked whether the participants filtered their tap water, drank bottled water, or drank unfiltered tap water. The researchers then compared the residential histories and drinking water habits with the levels of PFAS measured in the participants’ blood between 4 and 7 years after municipal treatment systems were installed.

The researchers found, in both communities, that people who lived there for longer periods of time had higher PFAS levels, reflecting years of accumulated exposure. In Hyannis, residents who lived there for more than 16 years had PFHxS levels that were 2.3 times higher and PFOS levels that were 1.4 times higher than residents who lived there for fewer than five years. PFHxS and PFOS are two types of PFAS that are commonly found in groundwater contaminated by firefighting foam.

Previous studies have focused on measuring PFAS in people’s blood shortly after their water is treated. “This study is among the first to show that people’s blood levels of PFAS can remain high up to seven years after water treatment is put in place,” says Dr. Laurel Schaider, a senior scientist at Silent Spring and the study’s lead investigator. “What’s more, their drinking water choices make a difference.”

In Hyannis, residents who reported using home water filters—the majority of whom began filtering before the town installed treatment in 2016—or who primarily drank bottled water had significantly lower PFAS levels than those who drank unfiltered tap water. The researchers did not observe the same pattern in Ayer, where drinking water contamination was less severe. Testing conducted between 2013 and 2015 revealed Hyannis had the highest PFAS levels of any public water supply in the state. Its residents also had higher PFAS blood levels.

The findings come at a time when the U.S. Environmental Protection Agency is proposing to roll back parts of the federal PFAS drinking water standards that were finalized in 2024, including extending the deadline for public water systems to comply with new legal limits on PFOA and PFOS, the two most common PFAS, and completely rescinding limits for four PFAS.

With thousands of communities across the United States grappling with PFAS contaminants in their drinking water, the researchers hope their study will help residents and public health officials make informed decisions about ways to reduce exposures. The study also shows that delaying more systemic solutions can have lasting consequences given that PFAS remain in the body for years after the water is treated.

“Our findings underscore the urgent need to reduce exposures as early as possible through municipal treatment, home filtration, or other measures in order to keep PFAS from building up in the body and reduce the risk of health problems later on,” says Schaider.

Funding for this study was provided by the U.S. Centers for Disease Control and Prevention (Award Number U01TS000313) and charitable donations to Silent Spring Institute.