Dynamics of Ionic Per- and Polyfluoroalkyl Substances (PFAS) in the Indoor Environment: Implications for Exposure

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic compounds that are persistent in the environment. Some have been associated with adverse health effects. Despite their presence in consumer products and materials in homes, where people spend ~70% of their time, few residential indoor measurements of PFAS exist in the US. Diet and ingestion of water are considered the main exposure pathways, but recent literature suggests that inhalation and ingestion of settled dust may also be important. As part of the Indoor PFAS Assessment (IPA) Campaign, indoor air, surfaces, settled dust, total suspended dust, and tap water were analyzed for 26 ionic PFAS. On average, residential indoor concentrations of PFAS on quartz fiber filter (QFF) collected PM2.5 were 3.4x higher than residential outdoor concentrations and 10x higher than regional background concentrations. Presence of PFAS on backup QFFs provides evidence that ionic PFAS are in both the gas- and particle-phase indoors and that the front filter is an upper-bound estimate of particle-phase PFAS. Differences in PFAS on windows and wall-mounted glass slabs highlight the importance of surfaces in mediating PFAS indoors. Perfluoroalkyl acid (PFAA) concentrations on glass slabs increased over longer sampling periods but were more variable on windows, suggesting that partitioning is more dynamic on windows and leading to hypotheses regarding the influence of window film growth and composition. Positive associations between gas-phase fluorotelomer alcohols (FTOHs) and window concentrations of some perfluorocarboxylic acids (PFCAs) suggest that precursors may transform to PFAAs indoors. Using measured concentrations of ionic and neutral PFAS in sampled residential indoor compartments, we found that inhalation contributed to over 76% of total PFAS intake for adults and 2-year-old children in these homes (excluding diet), driven by the neutral PFAS concentrations in air. Biotransformation of neutral PFAS in the body may also be a major source of indirect exposure to PFAAs. This dissertation provides insights into the dynamics of ionic PFAS in homes and identifies the importance of inhalation and ingestion as exposure routes. This work may allow researchers to better model PFAS fate and transport, and therefore exposure, and may provide insights that drive new hypotheses for future research.