Drinking water, select foods linked to PFAS in California adults

Food has long been considered a major source of per- and polyfluoroalkyl substances (PFAS), a large class of long-lasting chemicals used in industry, consumer products, and found in the environment that are hazardous to human health. A new study led by Boston University School of Public Health researchers (BUSPH) reveals that PFAS exposure through food appears to have declined among adults over the last two decades -- but drinking water remains an important source of these chemicals.

Published in the journal Environmental Science & Technology, the study examined associations between diet, drinking water, and "legacy" PFAS -- chemicals that were phased out of production in the US in the 2000s -- with blood samples from California residents. PFAS exposure was associated with consumption of seafood, eggs, and brown rice, but fewer other foods than suggested by earlier studies. PFAS levels were elevated among people who lived in areas where these chemicals were detectable in their drinking water supply, but lower than levels found in highly contaminated communities.

The findings published the same day the Environmental Protection Agency (EPA) announced that it will roll back first-ever limits on certain types of PFAS in drinking water, set by the Biden administration last year. The EPA also said it will uphold drinking water standards for two of the most harmful forever chemicals -- PFOA and PFOS -- but extended the deadline for water utilities' compliance with these rules, from 2029 to 2031.

The study provides the first analysis of the effects of diet and drinking water simultaneously on PFAS concentrations in blood, and it fills a critical gap in research on this topic. Most US information on PFAS in food relies on earlier European studies that cannot be fully applied to the US population or lifestyle due to differences in time of sampling, diet, food production, and industries. To understand and mitigate the harmful effects of PFAS on individuals and the environment, the US needs current data on the possible contributing sources of exposure.

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," says study lead and corresponding author Dr. Emily Pennoyer, a graduate of BUSPH's environmental health PhD program, and a student at the time of the study. "These findings emphasize the need to continue ongoing efforts to regulate PFAS in drinking water."

Known as "forever chemicals" because they are difficult to break down, some PFAS are linked to a number of diseases and other health conditions, including multiple cancers, liver damage, thyroid disease, decreased vaccine response, and developmental and reproductive complications.

For the study, Dr. Pennoyer and colleagues at BUSPH, the California Department of Public Health (CDPH), and California Department of Toxic Substances Control estimated associations among legacy serum PFAS concentrations, self-reported food consumption, and PFAS concentrations in public drinking water supplies. The 700 adult participants were selected from the California Regional Exposure Study, conducted from 2018-2020, which measures and compares environmental chemicals in people across the state to better understand how to reduce chemical exposure and improve public health.

The participants provided survey responses detailing demographic information and the frequency in which they consume red meat, poultry, seafood, dairy, eggs, potatoes, brown rice, takeout, and packaged foods that are heated at home. The researchers observed associations between legacy serum PFAS and consumption of seafood, eggs and brown rice, but overall, PFAS exposure through food appeared to be lower than earlier studies in other populations -- a surprising result to the team. This decline could be due, in part, to the Food and Drug Administration's decision to phase out legacy PFAS from manufacturing, and restrict certain PFAS in paper food contact materials.

"It is encouraging that we see fewer associations with food in this study, but concern about PFAS in some food groups remain," says study coauthor Dr. Nerissa Wu, biomonitoring California program lead at CDPH. "We will continue to work to understand how to lower PFAS levels in the California food supply."

While PFAS concentrations in the participants' drinking water was on average substantially lower than previous measurements in areas that have reported heavily contaminated water supplies, the team still observed significantly higher PFAS levels in participants living in water service areas with detectable PFAS, compared to those who lived in areas without detectable levels.

"The connections to drinking water are concerning and support California's efforts to evaluate and address PFAS contamination in drinking water supplies," says study coauthor Dr. Kathleen Attfield, head of the Biomonitoring California, Exposure Surveillance and Epidemiology Unit at CDPH.

In addition to gaining a better understanding of PFAS in the food chain, "more research is needed on indoor exposures to air, dust, and cosmetics, as well as analyses of newer, non-legacy PFAS," says study senior author Dr. Thomas Webster, professor of environmental health at BUSPH.

"Our findings further support the importance of upholding the federal drinking water standards promulgated by the U.S. Environmental Protection Agency," says study coauthor Dr. Wendy Heiger-Bernays, emeritus clinical professor of environmental health at BUSPH. "Efforts to ban or limit the use of PFAS, including emerging PFAS, are necessary to reduce their presence in the environment, including in food and water."

Consumers can make informed choices by purchasing products labeled "fluoro-free" when possible, she adds.