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Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals and ubiquitously present in the environment, including in homes. The two major exposure pathways for PFAS indoors are inhalation and accidental ingestion of house dust; however, the influence of dust particle size on PFAS exposure is not well understood to date. Thus, we are aiming to better understand the relationship between dust particle size and PFAS concentrations. We collected dust from 10 homes in North Carolina and seven homes in New York, sieved the dust into multiple size fractions ranging from <63 µm to <2,000 µm, and used targeted methods to analyze the fractions for PFAS. We found that many neutral PFAS are significantly (p < 0.05) and negatively correlated with dust particle size (mean Pearson correlation coefficient r = −0.70 to −0.90), i.e., higher concentrations were found in the smaller size fractions. This suggests that neutral PFAS concentrations in dust are primarily influenced by partitioning to the dust particles from the gas phase. On the other hand, several perfluoroalkyl acids showed no clear or positive correlations between particle size and concentration (mean Pearson r = −0.45 to 0.65), suggesting that additional migration pathways contribute preferentially to the larger size fractions, such as abrasion of fibers from upholstery. Dust-air partition coefficients, K′d, derived for neutral PFAS for a subset of homes reflect this observation, with higher log(K′d) values found for smaller dust size fractions compared to larger size fractions. This work highlights the importance of the choice of size fraction when analyzing PFAS in dust and for exposure assessments.
Eichler et al. (Tue,) studied this question.