TAP WATER INTAKE OF POLY- AND PERFLUOROALKYL SUBSTANCES (PFASS) IN RELATION TO SERUM CONCENTRATIONS IN A NATIONWIDE PROSPECTIVE COHORT OF U.S. WOMEN

Human exposure to poly- and perfluoroalkyl substances (PFASs) has been associated with many negative health impacts. PFAS exposure sources are diverse and include dust, food, drinking water, and many consumer products. Our previous work showed that drinking water supplies for 6 million U.S. residents exceed U.S. EPA’s lifetime health advisory. Numbers of point sources have been spatially correlated with PFAS detection in public water supplies.

Drinking water advisory levels have been adopted by many regulatory agencies to reduce chronic exposure. However, most U.S. advisory levels are based on the assumption of approximately 20% of overall PFAS intake comes from drinking water. Better characterizing the relative importance of drinking water to overall human exposures is important for developing health protective guidelines. Here we address this question by measuring concentrations of 11 PFASs in a subset (n=111) of matched archived tap water samples and serum samples from the Nurses’ Health Study (NHS), a nationwide U.S. based prospective cohort. The relative importance of home tap water for measured levels of PFASs in humans is evaluated using both statistical and mechanistic modelling approaches.

Our analysis suggests tap water may be a significant exposure source for five PFASs among NHS participants. In 1989-1990, the median contribution of tap water at the current residence to serum PFASs in NHS participants was 8.8% to 30% for the five PFASs modeled. This ratio varies across individuals and compounds by up to a factor of 2-3. The presentation will discuss how this ratio varies geospatially and whether it is associated with residential history. Pilot data also show increases in unquantified extractable organic fluorine in recent tap water, suggesting additional quantification would be worthwhile. Other exposure sources such as consumer products seem to dominant overall exposure of individuals in the NHS cohort prior to the restrictions and regulations of legacy PFASs in the U.S.