Association of combined exposure to polycyclic aromatic hydrocarbons, BTX and metals with metabolic syndrome risk

Despite the increasing prevalence of metabolic syndrome (MetS) worldwide, its environmental determinants in complex occupational settings remain unclear. This study aimed to evaluate the associations between occupational mixed exposure to polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, and xylene (BTX), and metals and MetS risk, and identify key pollutants for occupational health monitoring and risk management. We recruited 1205 coal chemical workers in central China and measured urinary levels of 14 PAH metabolites, 6 BTX metabolites, and 40 metals. Associations between mixed exposures and MetS and its components were analyzed using weighted quantile sum (WQS) regression and restricted cubic spline (RCS) models.Among the participants, 245 individuals (20.33%) were diagnosed with MetS. Exposure to PAH mixtures was significantly associated with an increased risk of MetS (OR = 1.28, 95% CI: 1.08, 1.52). Mixed exposure to BTX and PAHs further increased MetS risk (OR = 1.77, 95% CI: 1.35, 2.31). Notably, mixed exposure to PAHs, BTX, and metals was associated with a substantially increased risk of MetS (OR = 3.49, 95% CI: 2.38, 5.18), exceeding the effects observed for individual chemical groups.The study identified 9-hydroxyfluorene (9-OHFlu) and zinc (Zn) as key pollutants contributing to MetS risk among workers. Similar associations were observed for MetS components (high fasting glucose, triglycerides, low high-density lipoprotein cholesterol (HDL-C), high blood pressure). Mixed exposure to PAHs, BTX, and metals increased MetS risk more than single pollutants. 9-OHFlu and Zn were identified as key contributors, highlighting their importance for future occupational health monitoring and risk management.