ASSESSING POTENTIAL EXPOSURE TO PER- AND POLYFLUOROALKYL SUBSTANCES (PFAS) IN PRODUCE AND DRINKING WATER IN CHATHAM COUNTY, NC

Abstract

Diet constitutes a major human exposure pathway for per- and polyfluoroalkyl substances (PFAS) due to the contamination of drinking water supplies, and their use in food packaging, and accumulation in the food web. Significant PFAS levels have recently been reported in groundwater (Haw River and Cape Fear River) in North Carolina. This has raised concerns for potential exposure for communities consuming drinking water sourced from these rivers and produce grown from lands irrigated with this water. This study sought to evaluate dietary exposure to PFAS from consumption of produce (lettuce, potato and tomato) and drinking water in Chatham County, North Carolina, a previously reported PFAS impacted area. A total of 18 produce samples were collected in local farmer markets and grocery stores. Drinking water PFAS data (N = 40) were abstracted from an ongoing study in Pittsboro, NC collected and analyzed in 2019 and 2020. PFAS were generally not detected in the produce samples analyzed here, with the exception of perfluorodecanoic acid (PFDA). PFDA was detected in potatoes and tomatoes, ranging from 0.11 to 1.11 ng/g, or parts per billion (ppb). Total PFAS were measured at concentrations ranging from 26.4 ng/L up to 458.1 ng/L in the drinking water samples. Using the median values of PFDA measured in produce and estimates of produce consumption in the general population (using the 50th and 95th percentiles), exposure to PFDA was estimated. Estimated exposure was highest from potato consumption (median exposure intake varies between 0.42 and 1.40 ng/kg-day). In drinking water, short-chain (<8 carbon) perfluoroalkyl carboxylate acids (PFCA) contributed the most to ∑PFAS exposure. The median exposure intake was 1.40 ng/kg-day for PFHxA and 1.17 ng/kg-day for PFPeA. Higher exposure was generally observed via drinking water compared to produce, and exposures were the highest for young children and decreased with age. The estimated hazard index suggests that a small portion of the population (~5%) could be at increased risk for adverse effects via produce exposure (in young children) and for all age groups via drinking water exposure.