Harvesting Concerns: Fayetteville’s Garden Produce and Contaminated Watersheds

“Many people often think that contaminated drinking water is the main source of PFAS exposure,” comments Detlef Knappe, a professor in civil, construction, and environmental engineering at NC State and one of the main investigators of the study. “One of our primary aims was to find out whether residents living in PFAS-impacted areas are also exposed through the produce they grow themselves.”

The researchers gathered 53 samples of garden produce from five residential plots near the Fayetteville Works plant in Fayetteville, N.C. The samples were tested for 43 different PFAS, including GenX and 12 other per- and polyfluoroalkyl ether acids (PFEAs) specifically linked to the Chemours facility.

The detected PFAS concentrations in the sampled produce reached as high as 38 nanograms per gram (ng/g), with PFEAs from the manufacturer making up the majority of the PFAS detected.

Among the various types of produce examined, such as fruits, vegetables, and nuts, researchers found that water-dense items like berries and figs had the highest PFAS levels. A trend of decreasing PFAS levels was observed in frozen produce collected from the area over the years, specifically from 2013 to 2019, although some fluctuations were noted. The reasons for this decline are not fully understood, but researchers believe that steps taken to reduce air emissions at the nearby fluorochemical plant may have contributed.

Next, the researchers compared the PFAS exposure from eating contaminated produce with exposure from drinking water. They specifically assessed how much produce would equal the exposure to GenX from drinking water with a concentration of 10 ng/L of GenX, which is the highest amount permitted by the U.S. Environmental Protection Agency (EPA).

“We focused on GenX for this comparison since it’s the only PFEA with available toxicity data,” explains Pingping Meng, an assistant professor of chemistry at ECU and the lead author of the study.

For the location with the highest average concentration of GenX in the produce (0.19 ng/g), the study determined that daily consumption of drinking water with 10 ng/L of GenX equates to eating roughly 17 grams (0.6 ounces, or around 10 blueberries) for children, and about 68 grams (2.4 ounces) for adults. These amounts of produce are significantly lower—about nine times less for children and four times less for adults—than what is usually consumed in a typical diet of fruits and vegetables.

To evaluate the long-term risk of consuming GenX-tainted produce in affected communities, the researchers calculated a chronic exposure daily limit, indicating the maximum amount of contaminated produce that could be safely eaten daily.

For children aged 3 to 6, this limit was identified as 289 grams daily (approximately 10 ounces, or one and two-thirds cups of blueberries), exceeding the standard daily intake of 186 grams. However, the researchers caution that this risk may be underestimated because the analysis did not account for other PFAS present in the produce.

“We might be underestimating the overall risk as we have not looked at the potential combined effects of PFEA mixtures, especially for those detected in higher concentrations than GenX, for which there are no health-based reference doses,” Meng warns. “More research is needed to assess the toxicity of the primary PFEAs found in the produce.”

“Our findings indicate that individuals living near Fayetteville Works and who eat locally grown fruits and vegetables are being exposed to various PFEAs through their diet,” Knappe adds. “This underscores the fact that dietary intake, in addition to contaminated water, can be a significant pathway for human exposure.”