Phthalate exposure and the metabolic syndrome: A systematic review and meta-analysis

Phthalates are chemicals widely used in plastic-based consumer products, and human exposure is universal. They are classified as endocrine disruptors, and specific phthalate metabolites have been associated with an increased risk of cardiometabolic diseases. The aim of this study was to assess the association between phthalate exposure and the metabolic syndrome in the general population. A comprehensive literature search was performed in four databases (Web of Science, Medline, PubMed, and Scopus). We included all the observational studies that evaluate the association between phthalate metabolites and the metabolic syndrome available until January 31st, 2023. Pooled Odds Ratios (OR) and their 95% confidence intervals were calculated by using the inverse-variance weighted method. Nine cross-sectional studies and 25,365 participants aged from 12 to 80 were included. Comparing extreme categories of phthalate exposure, the pooled ORs for the metabolic syndrome were: 1.08 (95% CI, 1.02-1.16, I² = 28%) for low molecular weight phthalates, and 1.11 (95% CI, 1.07-1.16, I² = 7%) for high molecular weight phthalates. For individual phthalate metabolites, the pooled ORs that achieved statistical significance were: 1.13 (95% CI, 1.00-1.27, I² = 24%) for MiBP; 1.89 (95% CI, 1.17-3.07, I² = 15%) for MMP in men; 1.12 (95% CI, 1.00-1.25, I² = 22%) for MCOP; 1.09 (95% CI, 0.99-1.20, I² = 0%) for MCPP; 1.16 (95% CI, 1.05-1.28, I² = 6%) for MBzP; and 1.16 (95% CI, 1.09-1.24, I² = 14%) for DEHP (including ΣDEHP and its metabolites). In conclusion, both low molecular weight and high molecular weight phthalates were associated with an 8 and 11% higher prevalence of the MetS, respectively. The exposure to six specific phthalate metabolites was associated with a higher prevalence of the MetS.