Asthma and decreased lung function in children exposed to perfluoroalkyl and polyfluoroalkyl substances (PFAS): An updated meta-analysis unveiling research gaps.

Background And Objective: Associations between exposure to per- and polyfluoroalkyl substances (PFAS) and pediatric asthma and reduced lung function in children are mixed and inconclusive. The study objective was to examine the extant research on exposure to PFAS and the diagnosis of asthma or decreased lung function in children <17 years of age to highlight what is known and to identify research gaps for future investigations.

Methods: The present review was registered on the PROSPER database (CRD42023407172). We systematically searched several bibliographic databases (Scopus, Embase, Web of Science (core Collection), Medline, and CINAHL) along with grey literature sources in January 2023 to find relevant studies before this date. The National Toxicology Program's Office of Health Assessment and Translation (NTP OHAT) tool was applied to assess the risk of bias (RoB) assessment. We used a random-effects meta-analysis to assess the associations. From 12 observational epidemiological studies (out of 513) explored for qualitative analyses, 4 studies were included in quantitative analyses.

Results: The meta-analysis revealed a significant association between exposures to perfluorooctanoate (PFOA) with the prevalence of children's asthma [Odds Ratios (OR) = 1.162 (95% CI: 1.004-1.321)] whereas the association for perfluorooctane sulfonate (PFOS) was not statistically significant [OR = 1.03 (95%CI: 0.806-1.265]. The narrative synthesis results of the four included studies that examined the effects of PFAS exposure on lung function did not demonstrate significant associations between exposure to PFAS and decreased lung function. The RoB for most included studies was assessed as probably low without serious limitations. However, two studies were at high risk of biases.

Conclusion: Our findings suggest that children who are exposed to PFOA are at a higher risk of developing asthma as well as the association between exposure to PFOS with impaired lung function. Large longitudinal studies with homogeneous PFAS exposures and standardized outcome measures are needed to ascertain these outcomes with improved certainty as well as toxicological studies to investigate the underlying mechanisms.