A recent study has uncovered significantly elevated levels of ultrashort-chain per- and polyfluoroalkyl substances (PFAS) in blood samples from residents of Wilmington, North Carolina, collected between 2010 and 2016. Researchers detected two specific ultrashort-chain PFAS—perfluoromethoxyacetic acid (PFMOAA) and trifluoracetic acid (TFA)—in nearly all samples analyzed. In contrast, GenX, a chemical that raised public concern regarding PFAS contamination in the Cape Fear River Basin, appeared in only 20% of the samples.
This research contributes to the growing evidence that short-chain PFAS can accumulate within the human body. The compounds PFMOAA and TFA have not been extensively studied in humans due to previous beliefs that they did not bioaccumulate because of their chemical structure, as well as the lack of reliable analytical methods for detecting them in blood samples until recently. According to Detlef Knappe, a professor at NC State University and co-corresponding author of the study, the advancement in analytical techniques has revealed these ultrashort-chain PFAS as prevalent in both environmental samples and human blood.
In 2016, researchers from NC State and the U.S. Environmental Protection Agency published findings indicating high concentrations of various PFAS, including GenX, in the drinking water of Wilmington residents. This contamination stemmed from the Fayetteville Works plant, which has been discharging PFAS into the Cape Fear River, the primary source of drinking water for the city, since 1980. Following 2017, the chemical manufacturer was mandated to manage PFAS emissions into both the river and the atmosphere.
The current study examined 56 different PFAS in water samples from the Cape Fear River, collected in 2017, along with 119 adult blood serum samples from a biobank at the University of North Carolina (UNC) that were gathered between 2010 and 2016. Though all serum samples were anonymized, they were collected from residents in and around Wilmington. The results were unexpected; 34 of the 56 PFAS were found in at least one blood serum sample. Notably, five PFAS constituted 85% of the total detected.
PFMOAA exhibited the highest median concentration at 42 nanograms per milliliter (ng/mL), making up 42% of the total, followed by TFA (17 ng/mL), PFOS (14 ng/mL), PFOA (6.2 ng/mL), and PFPrA (5.4 ng/mL). Furthermore, TFA represented 70% of the total PFAS concentration in the 2017 water sample, recorded at 110,000 nanograms per liter (ng/L), while PFMOAA measured at 38,000 ng/L. Although TFA can originate from various sources, including fluorinated refrigerants, the study highlights that the Fayetteville Works facility was the primary contributor to the concentrations of both TFA and PFMOAA in the lower Cape Fear River.
“For context, European guidelines suggest a safe drinking water level of 2200 ng/L for TFA,” Knappe stated. “Our sample exceeded this limit by over 50 times.”
“These data provide a “timestamp” of exposure prior to public awareness of drinking water contamination,” remarked Jane Hoppin, a professor of biological sciences and principal investigator of the GenX Exposure Study at NC State. “The prevailing belief is that short-chain PFAS are less concerning because they supposedly do not bioaccumulate, yet our findings suggest they can be present in significant concentrations in humans.”
Hoppin emphasized the necessity for further investigation into the human health effects of these PFAS, particularly TFA and PFMOAA. “The current understanding of the health impacts of these chemicals is limited. Most substances in the PFAS group have been associated with liver and immune system effects, but research is still in its early stages for many of them.”
Future efforts will involve analyzing samples from the GenX Exposure Study to assess levels of TFA and PFMOAA. “This sample set offers insight into past exposure,” Hoppin explained. “Evaluating the current levels will aid in understanding how these chemicals accumulate in the body and their potential health implications.”
The study has been published in the journal Environmental Science and Technology and received funding from the National Institute of Environmental Health Sciences, the Center for Human Health and the Environment at NC State University, and the North Carolina Collaboratory at the University of North Carolina at Chapel Hill, with financial support from the North Carolina General Assembly. The research team also included Lan Cheng, Sarah Teagle, Jeffrey R. Enders, and Rebecca A. Weed, with contributions from Hazel B. Nichols from UNC-Chapel Hill”s Gillings School of Public Health.
