Associations between exposure to environmental pollutants, metabolic syndrome risk, and obesity-related anthropometric indices.

Environmental pollutants-including heavy metals, phthalates, bisphenol A (BPA), polycyclic aromatic hydrocarbons (assessed via urinary 1-hydroxypyrene), and volatile organic compounds (assessed via benzene metabolites)-have been linked to metabolic dysfunction. Yet, population-based evidence across age groups remains limited. This study examined associations between exposure to multiple pollutants and metabolic syndrome (MetS) and its components, focusing on novel obesity-related anthropometric indices that capture subtle metabolic alterations. Originally designed as a case-control study, it was analyzed cross-sectionally among 536 participants aged ≥10 years at a tertiary hospital in Riyadh, Saudi Arabia. Biomarkers of metals, phthalates, BPA, PAHs, and benzene were quantified in blood and urine. MetS components and advanced anthropometric indices-A Body Shape Index (ABSI), Waist-to-Height Ratio (WHtR), Conicity Index (CI), Waist-Triglyceride Index (WTI), Body Roundness Index, Visceral Adiposity Index, Lipid Accumulation Product, and Cardiometabolic Index-were evaluated using multivariable logistic and linear regression adjusted for relevant covariates, with percent change expressing relative change in outcomes per ln-unit increase in pollutant concentration. In adults (≥18 years), no pollutant was significantly associated with MetS; however, blood cadmium was linked to higher WHtR (+2.4 %) and CI (+1.1 %) and lower fasting glucose (-3.1 %), while mercury increased fasting glucose (+1.7 %), ABSI (+0.6 %), and CI (+0.6 %). Urinary 1-hydroxypyrene was positively associated with ABSI and CI (∼+0.9 %), and the cumulative blood-metal index increased ABSI (+1.9 %) and CI (+2.1 %). In children (<18 years), arsenic increased systolic pressure (+1.2 %), whereas lead and DEHP metabolites showed inverse associations with diastolic pressure, triglycerides, and central adiposity indices. Metals exerted stronger effects in adults, whereas phthalate-related associations appeared inverse in children, underscoring age- and matrix-dependent exposure-response differences and the value of advanced anthropometric indices for detecting early pollutant-related metabolic alterations.