Indoor Residential Exposure to PFAS and Emissions to the Outdoor Environment: Results from the IPA Campaign
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The indoor environment is a potentially important location for exposure to per- and polyfluoroalkyl substances (PFAS) because people spend roughly 90% of their time indoors, where they frequently consume food and water, and store/use materials, articles and consumer products that contain PFAS. Additionally, PFAS concentrations in indoor air are typically higher than outdoors, and thus, buildings can be a source of PFAS to outdoor air. As part of the UNC Indoor PFAS Assessment (IPA) Campaign, we measured 9 neutral and 26 ionic PFAS in the air, dust, water, surfaces, cloth, and clothing in 10 homes in North Carolina over 9 months using ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometry (AB SCIEX Triple QuadTM 6500; UHPLC/ESI-MS/MS) or gas chromatography/electron impact mass spectrometry (Agilent; GC/EI-MSD). Using these data, we estimated indoor residential PFAS exposures via inhalation, ingestion and dermal routes for adults and 2-year-olds. Dietary exposures were not assessed. Exposures were dominated by neutral PFAS, and inhalation accounted for the majority of estimated exposure for both adults and 2-year-olds. Ingestion of PFAS from dust, surfaces and mouthing of fabrics was also a substantial contributor to 2-year-old exposure. Ingestion of PFAS from water, dust and surfaces were the main pathways for exposure to ionic PFAS. Dietary intake is poorly constrained, but literature values suggest that accounting for diet would roughly double exposures. We further estimate the indoor-to-outdoor emission rate of these 35 PFAS from all US single family homes to be approximately 3,200 kg yr-1, dominated by neutral PFAS.