The Characterization of Per- and Polyfluoroalkyl Substances (PFAS) in Nebraska Drinking Water and Human Health Impacts

Per- and polyfluoroalkyl substances (PFAS) are synthetic compounds that have been detected in water sources of urban and rural environments with evidence of adverse human health effects from exposure. Humans are primarily exposed through ingestion of contaminated water and food. PFAS exposure has been linked to negative multi-system health outcomes (liver, kidneys, cardiovascular, reproductive, and immune). PFAS occur as persistent mixtures in environmental media with decades long consequences to water quality. While national agencies have launched large-scale PFAS water quality monitoring studies, limited data exists for contamination of rural water in Nebraska, especially private wells. The aims of this study were: 1) explore the spatial patterns and variations of PFAS across rural Nebraska; 2) determine the PFAS profile in drinking water and risk estimates to human health; 3) characterize human health effects of PFAS exposure and explore any other predictors of PFAS exposure in the study population. Our findings from Chapter II indicate varying geospatial patterns of PFAS across the state. The spatial pattern of PFAS was generally diffuse with non-point sources as a more important contributor than point sources to rural Nebraska PFAS-related water quality. Hot spots of predicted concentrations above 4 ng/L were identified at two of the sampling sites. These results indicate vulnerable areas in Nebraska that require further data collection or modeling of PFAS in drinking water and other environmental media. These insights can also extend beyond PFAS to other water contaminants because populations are often exposed to chemical mixtures. The findings in Chapter III identified the types of PFAS present and concentrations in drinking water. PFAS occurrence was common in rural Nebraska drinking water (98% detection frequency) but at low concentrations (< 4 ng/L) with high variability of PFAS concentrations in private well water sources (max 108 ng/L). Town and water source were significant predictors of ∑PFAS concentrations. The PFAS risk profile from samples measured in this study represented minimal risk with a hazard index (HI) of 1.90. The estimated health risk resulting from our HI screening should be taken into consideration for future water quality monitoring efforts, but the HI values should be interpreted with extreme caution. Community specific recommendations should be provided given that the patterns and concentrations of PFAS contamination were inconsistent across the state. Chapter IV found there were no significant effects of PFAS concentrations in drinking water and the health outcomes of interest in this study. Age and years lived at residence could be related to other confounding variables that were not included in this study like bioaccumulation rate. Predictor variables to consider for future PFAS drinking water studies include bioaccumulation rate, length of exposure, tap water consumption rate, and dietary food quality. The positive correlation found between socioeconomic groups and ∑PFAS concentration deserves more attention in future studies to determine the influence of this variable in the context of rural communities. The results from this research provide a better understanding of the scope of PFAS contamination in rural Nebraska. This data will add to the growing body of PFAS water quality data in Nebraska, broadening the national surveillance of PFAS in drinking water.