Human exposure pathways to poly- and perfluoroalkyl substances (PFAS) from indoor media: A systematic review

Abstract

Background: Human exposure to per- and polyfluoroalkyl substances (PFAS) has been primarily attributed to contaminated food and drinking water. There is information indicating other sources and pathways of exposure in residential environments, but few studies report relationships between these indoor media and human biomonitoring measurements.

Methods: This study adapts existing systematic review tools and methodologies to synthesize evidence for PFAS exposure pathways from indoor environment media including consumer products, household articles, cleaning products, personal care products, and indoor air and dust. Studies were identified using innovative machine learning approaches and pathway-specific search strings to reduce time needed for literature search and screening. The included studies and systematic review were evaluated using tools modified specifically for exposure studies. The systematic review was conducted following a previously published protocol (DeLuca et al., 2021) that describes the systematic review methodology used in detail.

Results: Only 7 studies were identified that measured the targeted subset of 8 PFAS chemicals in concordant household media (primarily house dust) and participant serum. Data extracted from the included studies were used to calculate exposure intake rates and estimate a percentage of occupant serum concentrations that could be attributed to the indoor exposure pathways. These calculations showed that exposure to PFOA, PFOS, PFNA, and PFHxS from contaminated house dust could account for 13%, 3%, 7%, and 25% of serum concentrations, respectively. Inhalation of PFAS in indoor air could account for less than 4% of serum PFOA concentrations and less than 2% of serum PFOS and PFNA concentrations. A risk of bias was identified due to participant profiles in most of the studies being skewed towards white, female, and higher socioeconomic status.

Conclusions: Along with synthesizing evidence for estimated contributions to serum PFAS levels from indoor exposure media, this systematic review also identifies a consistent risk of bias across exposure study populations that should be considered in future studies. It highlights a major research gap and need for studies that measure concordant data from both indoor exposure media and participant serum and the need for continued research on exposure modeling parameters for many PFAS chemicals.

Fig. 1.

Flow diagram showing literature search and screening steps followed during the systematic review. N indicates the number of studies screened in each step.

Fig. 2.

Risk of bias ratings in four domains for each included study. Solid blue indicates rating of “good,” checkered blue indicates rating of “adequate,” and solid orange indicates rating of “deficient” for that domain.

Fig. 3.

Percent serum concentration attributed to exposure from house dust ingestion and dermal contact for A) PFOS, B) PFOA, C) PFNA and D) PFHxS. Black dashed line indicates the weighted mean of all studies, weighted by sample size. Dark gray shading indicates adult populations and light gray shading indicates child populations. Note: y-axis scale for Figures A and C is different than scale for Figures B and D. Other study characteristics can be found in Table 1.

Fig. 4.

Percent serum concentration attributed to exposure from indoor air inhalation for PFOA, PFNA and PFOS. Dark gray shading indicates adult populations and light gray shading indicates child populations. Other study characteristics can be found in Table 1.