Abstract
Exposure to per- and polyfluoroalkyl substances (PFAS), ubiquitous persistent environmental contaminants, has led to substantial global concern due to their potential environmental and human health effects. Several epidemiological studies have assessed the possible association between PFAS exposure and risk of metabolic syndrome (MetS), however, the results are ambiguous. The aim of this study was to assess the current human epidemiologic evidence on the association between exposure to PFAS and MetS. We performed a systematic search strategy using three electronic databases (PubMed, Scopus, and Web of Science) for relevant studies concerning the associations of PFAS with MetS and its clinical relevance from inception until January 2021. We undertook meta-analyses where there were five or more studies with exposure and outcomes assessments that were reasonably comparable. The pooled odd ratios (ORs) were calculated using random effects models and heterogeneity among studies was assessed by I2 index and Q test. A total of 12 cross-sectional studies (10 studies on the general population and two studies in the occupational settings) investigated the association between PFAS exposure and MetS. We pooled data from seven studies on the general population for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) and five studies for perfluorohexanesulfonate (PFHxS) and perfluorononanoic acid (PFNA). Predominately, most studies reported no statistically significant association between concentrations of PFAS and MetS. In the meta-analysis, the overall measure of effect was not statistically significant, showing no evidence of an association between concentrations of PFOA, PFOS, PFNA, and PFHxS and the risk of MetS. Based on the results of the meta-analysis, current small body of evidence does not support association between PFAS and MetS. However, due to limited number of studies and substantial heterogeneity, results should be interpreted with caution. Further scrutinizing cohort studies are needed to evaluate the association between various and less well-known PFAS substances and their mixture with MetS and its components in both adults and children in different settings.
Highlights
Per- and polyfluoroalkyl substances (PFAS) have become a serious global concern due to their ubiquitous presence in the environmental
This study reported that serum PFAS levels in male firefighters were not associated with an elevated risk of metabolic syndrome (MetS), a positive association was observed between elevated diastolic blood pressure (DBP) and PFOS [24]
While increased serum total cholesterol and low‐density lipoprotein (LDL)‐cholesterol are strongly associated with PFAS exposure in humans, there is insufficient evidence with contradictory results for associations between exposure to PFAS and insulin resistance, diabetes, obesity, and hypertension [6, 7]
Summary
Per- and polyfluoroalkyl substances (PFAS) have become a serious global concern due to their ubiquitous presence in the environmental. PFAS have a carbon backbone with one or more fluorine substitutions and functional end groups which provide specific properties. The extremely strong carbon-fluorine bond, results in high chemical, thermal and biological stability of PFAS. Diverse PFAS are used in a wide variety of commercial products and industrial applications since the 1940s and can be found in everyday household products [1]. Direct exposure to PFAS in humans can occur through eating and drinking contaminated food and water, household dust or via occupational related exposure [2]. PFAS do not appear to undergo metabolism in the liver or other tissues and can persist in the body by binding to liver and serum proteins.
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