A new study suggests that while exposure to "legacy" per- and polyfluoroalkyl substances — or PFAS — through diet may be decreasing, at least in some adult populations, certain foods and drinking water may still be notable sources of the hazardous substances. 

What's happening?

PFAS are also known as "forever chemicals" because they can persist in the body and in nature for extended periods. Many "legacy" PFAS have been phased out in the United States since the early 2000s — while other PFAS remain in active use. But, according to the co-authors of a new study, even these phased-out substances can "remain ubiquitous in the environment and are still detected in humans decades later." Legacy PFAS — longer-chain perfluoroalkyl acids, such as PFOA — are also still being produced in some countries.

The study, published in May in the journal Environmental Science & Technology, suggests that exposure to legacy PFAS through food consumption has declined over the past 20 years among a study population of California adults. Meanwhile, seafood, eggs, and brown rice may, according to the study's survey, remain sources of interest. Contaminated drinking water is also considered a significant source.

Innovation News Network summarized the recent research, which looked at the relationship between diet and drinking water and blood serum levels of legacy PFAS. "While we observed fewer dietary associations compared to previous studies, diet and water may still be an important source of exposure in the general population," lead study author Emily Pennoyer said, per INN. "These findings emphasize the need to continue ongoing efforts to regulate PFAS in drinking water."

Among the study's findings were indications that residents of areas with detectable PFAS in the tap water had higher levels of these chemicals in their blood. 

The co-authors also noted that while diet was not found in this study population to carry as many associations with exposure "compared to findings in other populations from many years ago," improving understanding of exposure sources could benefit from "paired measurements of PFAS in food, water, and serum" as well as "additional PFAS and exposure pathways." 

The additional pathways to be further assessed could include indoor air quality.

Why are PFAS concerning?

PFAS are a large group of man-made chemicals, many of which are still used in countless everyday products, from water-resistant clothing and stain-resistant furniture to non-stick cookware and cosmetics. 

While medical research is ongoing, the chemicals have been linked to serious health concerns. 

For example, one study found that exposure to PFAS can alter the expression of certain genes in the brain. Another found an association between exposure and an increased risk of cardiovascular diseases in postmenopausal women. PFAS have also been linked with cancer, liver disease, thyroid disease, birth defects, and lower sperm counts, among other issues.

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Most Americans have already been exposed to PFAS and have the chemicals present in their blood, according to the Agency for Toxic Substances and Disease Registry. A 2024 study also found that more than 20% of Americans may have been exposed to PFAS-contaminated groundwater.

What's being done about PFAS?

PFOA — a legacy PFAS used to make products resistant to stains, grease, soil, and water — was banned in 2020 as part of the Stockholm Convention, a health treaty of 186 countries. It is still used in some countries, however.

More recently in the U.S., concerns have been raised among experts and advocates regarding the current presidential administration's rollback of a plan to limit PFAS in drinking water. 

Meanwhile, state governments have been taking steps to mitigate exposures. Maine, for example, recently banned the use of firefighting foam containing these chemicals at the former Brunswick Naval Air Station, where a spill in 2024 caused a massive PFAS contamination. 

Interestingly, concerns over PFAS-containing foam have led to innovation. An alternative fire-suppressing foam made from soybeans is already being used in dozens of fire departments, many in the Midwest, where soybeans are a major agricultural product.

Further investigation of the "additional PFAS and exposure pathways" beyond diet has the potential to uncover other creative solutions to contamination.

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