The Air that we Breathe: Neutral and volatile PFAS in Indoor Air.

Maya E Morales-Mcdevitt,Simon Vojta,Jitka Becanova,Melissa Woodward,Rainer Lohmann,Thomas A Bruton,Arlene Blum

doi:10.1021/acs.estlett.1c00481

Abstract

Sources of exposure to per- and polyfluorinated alkyl substances (PFAS) include food, water, and given that humans spend typically 90% of our time indoors, air and dust. Quantifying PFAS prevalent indoors, such as neutral, volatile PFAS, and estimating their exposure risk to humans is thus important. To accurately measure these compounds indoors, polyethylene (PE) sheets were employed and validated as passive detection tools, and analyzed by gas chromatography-mass spectrometry. Air concentrations were compared to dust and carpet concentrations reported elsewhere. Partitioning between PE sheets of different thicknesses suggested that interactions of the PEs with the compounds are occurring by absorption. Volatile PFAS, specifically fluorotelomer alcohols (FTOHs), were ubiquitous in indoor environments. For example, in carpeted Californian kindergarten classrooms, 6:2 FTOH dominated with concentrations ranging from 9-600 ng m-3, followed by 8:2 FTOH. Concentrations of volatile PFAS from air, carpet and dust were closely related to each other, indicating that carpets and dust are major sources of FTOHs in air. Nonetheless, air posed the largest exposure risk of FTOHs and biotransformed perfluorinated alkyl acids (PFAA) in young children. This research highlights inhalation of indoor air as an important exposure pathway and the need for further reduction of precursors to PFAA.

Highlights

Neutral polyfluorinated alkyl substances (PFAS) were successfully measured in outdoor air and water using PE sheets
The total estimated daily intake (EDI) of neutral PFAS via air and dust was calculated from PFAS concentrations measured here, and dust concentrations reported elsewhere17 based on established methods 18,19
Mean log KPE-air values from the fluorotelomer alcohols (FTOHs) of this study were approximately three log units lower than those reported for outdoors16 where break-through and environmental factors could have affected the partitioning of the compounds

Summary

Introduction

Human exposure to fluorotelomer alcohols (FTOHs), perfluorooctane sulfonamides (FOSAs) and perfluorooctane sulfonamidoethanols (FOSEs) and other precursors to perfluoroalkyl acids (PFAA) comes primarily from consumer and industrial products readily available in people’s homes.1–4 FTOHs were the dominant polyfluorinated compounds in indoor air 5 where ~60% of detected per- and polyfluorinated alkyl substances (PFAS) were associated with the particle phase.2 Since most people spend more than 90% of their time indoors,2 indoor air and dust are important uptake pathways for human PFAS exposure6 in addition to the widely recognized exposure sources of diet and water.7–9 correlations between elevated indoor air exposure to precursors and increased PFAS serum concentrations have been reported.10,11The use of passive sampling, which can measure the concentration of freely dissolved or gas-phase trace organic contaminants, has been widely accepted as an effective detection tool.12,13 Single-phase polymers, such as polyethylene (PE) sheets, have been able to detect a wide range of non-polar and moderately polar contaminants in the gas phase or dissolved in water.14,15 In addition, PE sheets are inexpensive, easy to handle, and can be transported and deployed.13 Recently, neutral PFAS were successfully measured in outdoor air and water using PE sheets.16 the partitioning of neutral PFAS into or onto the PE sheets indoors is not yet fully understood. The partitioning constants of neutral PFAS between PE and air (KPE-air) were derived in the validation study as: C The total estimated daily intake (EDI) of neutral PFAS via air and dust was calculated from PFAS concentrations measured here, and dust concentrations reported elsewhere17 based on established methods 18,19 (for details, see SI).

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Results

Conclusion