Human exposure pathways to poly- and perfluoroalkyl substances (PFAS) from indoor media: A systematic review protocol.
Human exposure to per- and polyfluoroalkyl substances (PFAS) has been primarily attributed to contaminated food and drinking water. However, additional PFAS exposure pathways have been raised by a limited number of studies reporting correlations between commercial and industrial products and PFAS levels in human media and biomonitoring. Systematic review (SR) methodologies have been widely used to evaluate similar questions using an unbiased approach in the fields of clinical medicine, epidemiology, and toxicology, but the deployment in exposure science is ongoing. Here we present a systematic review protocol that adapts existing systematic review methodologies and study evaluation tools from the U.S. EPA’s Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments and the Navigation Guide to exposure science studies in order to identify important PFAS exposure pathways from indoor media including consumer products, household articles, cleaning products, personal care products, plus indoor air and dust. Included studies selected will present exposure measures from indoor media paired with PFAS concentrations in blood serum, focusing on a subset of PFAS chemicals including perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), perfluorobutanoic acid (PFBA), perfluorobutane sulfonate (PFBS), perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonate (PFHxS), and perfluorononanoic acid (PFNA). Initial searches of Web of Science, PubMed, and ProQuest databases identified approximately 6,000 studies that will be prefiltered at the title and abstract level using computationally intelligent search strings to expedite the screening process. Studies will be screened against inclusion criteria by two independent reviewers, and the exposure assessment methods used in included studies will be evaluated using an approach modified from established systematic review tools for exposure studies. Extraction and summary of included study characteristics such as exposure medias, PFAS chemicals measured, and the types or regions of populations studied will be performed in DistillerSR software, visualized in Tableau, and will be available for download. The feasibility of conducting a meta-analysis will be determined during the systematic review based on the amount and quality of data collected within the scope of the review. This study presents innovative SR methodologies and tools for exposure science studies, including the development of exposure pathway-specific search strings that can expedite the scoping and screening processes. The evidence generated will increase our understanding of exposure to PFAS from indoor environment media, identify key data gaps, and inform future research priorities.