Poly- and perfluoroalkyl substances (PFAS) are a group of persistent, toxic chemicals used in many consumer products. They get released into the environment during their manufacture, use, and disposal resulting in the contamination of surface and groundwater, aquatic and terrestrial organisms, sludge (biosolids), soils, and some compost. This has led to PFAS being found in the blood of most people, with some of the highest levels among people with contaminated drinking water or occupational exposures. Exposure to PFAS can have detrimental reproductive, developmental, liver, kidney, and immunological effects. While drinking water is the dominant exposure pathway for those with contaminated water, contaminated food is likely the primary exposure pathway for the general population. Known dietary sources of PFAS include ingestion of foods from grease-resistant paper packaging such as microwave popcorn, fish, and wildlife harvested from areas impacted by local contamination of surface and drinking water. Elevated PFAS concentrations in meat, eggs, dairy products, fruits, and vegetables have also been reported, indicating a need to investigate exposure pathways for livestock and produce in areas near fluorochemical production plants and/or contaminated sites. Therefore, we aim to characterize human exposure to PFAS from foods in and near PFAS-impacted sites in Michigan. Our overarching hypothesis is that PFAS-impacted sites will contribute to elevated concentrations in foods and human dietary exposure. This project will advance our understanding of human dietary exposure to PFAS from impacted sites. Specifically, we investigated these questions at two sites. One is an agricultural cornfield (Chapter 2) we investigated the variability in bioaccumulation for corn kernels grown in soil impacted by PFOS-impacted biosolids (≤ 2100 ng/g-dry weight of PFOS) by first estimating kernel concentrations using the range of literature-derived BAFs and then directly measuring kernel concentrations. Our overall findings indicate that corn kernels accumulate little to no PFOS under certain field conditions, even when soils are highly contaminated with PFOS. Also, inaccurate measurement of PFAS in food may contribute to high variability in BAFs and such variability can result in substantial uncertainty in exposure and risk assessment. For the other two chapters, we investigated a community with high levels of PFAS in drinking water (>1,000 ppt) due to the historic use and disposal of laminated paper products from a former paper mill. Food produced at local farms (Chapter 3) was collected to compare PFAS concentrations in foods near the contaminated site with background. Overall, our results indicate that even seasonal ingestion of foods produced near PFAS-impacted sites can increase dietary PFAS exposure. The Site egg composite contained predominantly PFOS whereas produce was predominant for other PFAS with the highest concentrations in foods with higher water content (e.g., squash and leafy greens). While Total PFAS was highest in Site eggs, exposure for toddlers was highest for squash due to its higher consumption rate among that age group. Also, biological, and environmental samples such as drinking water, garden soil, produce, and other local foods (Chapter 4) were collected from homes in the community. Additional food and soil samples were collected from non-impacted areas. We estimated dietary exposure to PFAS via the homegrown, locally captured, and home-raised for individuals in a community with historically contaminated drinking water. We found that this pathway can be an important ongoing source of exposure less than the drinking water pathway. The concentrations of 40 PFAS were measured in all the biological and environmental samples using high-performance LC-MS/MS and human exposure was estimated for the impacted and non-impacted areas in Michigan. The overall goal of this project is to advance our understanding of the impacts of PFAS on human exposure from contaminated soil and uptake into foods near impacted areas.
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