Short-Chain PFAS Eclipse Their Longer Counterparts in Blood Serum

Long-chain PFAS are thought to be more likely to accumulate in the body and pose greater health risks than short ones. But it seems that the majority of PFAS blood serum content of people exposed to contaminated drinking water was composed of ultrashort-chain PFAS.

Per- and polyfluoroalkyl substances (PFAS) are synthetic molecules found in a wide range of consumer products, from non-stick pans to stain-resistant carpets. They are often called “forever chemicals” due to their persistence in the environment as well as living organisms.

People are typically exposed to PFAS when they consume food or water that has been contaminated by the chemicals. Due to the molecules’ potential health hazards, environmental agencies around the world have been working towards phasing them out.¹ Such restrictions have largely focused on longer-chain PFAS as some scientists previously found that they are more likely to accumulate in the human body and thus pose greater health threats.²

But recently, researchers led by Jane Hoppin, an environmental epidemiologist at North Carolina State University, found that two ultrashort-chain PFAS persisted in most of the blood serum samples from people who were exposed to PFAS-contaminated drinking water.³ Together, the two molecules consisted of nearly 60 percent of all serum PFAS. The team’s findings, published in Environmental Science & Technology, may reframe future PFAS research and regulation.

“The conventional wisdom is that short-chain PFAS are of lesser concern because they don’t bioaccumulate, but what we’re seeing is that they can occur at high levels in people,” Hoppin said in a statement.

People who live near PFAS manufacturing facilities, such as Fayetteville Works in North Carolina, are at a higher risk of exposure. Fayetteville Works had released PFAS-tainted wastewater for decades, causing high PFAS levels in the drinking water that more than 200,000 residents consumed.^4-6 Most afflicted individuals were likely unaware of their exposure until Wilmington Star News, a local newspaper serving the area, reported the issue in June 2017.

In a previous study, Hoppin’s team measured PFAS levels in the blood serum of about 350 Wilmington residents aged six to 86 within several months following the news report.⁷ However, the researchers noted that Fayetteville Works quickly agreed to manage their wastewater, and the level of the chemicals in drinking water declined rapidly. This may have obscured some of the real-time effects of the exposure.

To address this gap, in the present study, the researchers analyzed blood sera from approximately 100 adults in North Carolina, which had been collected between 2010 and 2016, before any PFAS wastewater management-related changes were made. The samples originated from individuals who enrolled in the University of North Carolina Cancer Survivorship Cohort but were excluded because they did not have a history of cancer.

Hoppin’s team quantified 56 PFAS in these samples using liquid chromatography and mass spectrometry. They found two ultrashort-chain PFAS, perfluoro-2-methoxyacetic acid (PFMOAA) and trifluoroacetic acid (TFA), which contained two or fewer fluorinated carbons, in 99 percent and 77 percent of samples, respectively. PFMOAA and TFA also dominated the serum PFAS content—in total, the two comprised 59 percent of all PFAS. This contrasted with long-chain PFAS, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which together made up less than 20 percent of total serum PFAS content.

“These results point out the need to start thinking about how to study the human health effects of these [short-chain] PFAS,” Hoppin said. She added that it is likely also important to compare past PFAS levels to present levels to “help us determine how these chemicals accumulate in the body and what their health effects might be.”