Association of heavy metal exposure via drinking water with obesity: a cross-sectional study in Ahvaz, Iran

There is growing evidence that heavy metals may contribute to obesity through endocrine disruption and oxidative stress, yet studies in Middle Eastern populations remain scarce. This cross-sectional study investigated the association between heavy metal concentrations in drinking water and obesity among 180 adults in Ahvaz, Iran. Participants were divided into obese (BMI ≥ 30 kg/m 2 ) and non-obese (BMI < 30 kg/m 2 ) groups. Concentrations of six heavy metals (Pb, Hg, As, Cd, Ni, Cr) were measured in urine and drinking water samples using atomic absorption spectrophotometry. Spatial analysis (Global Moran’s I) was conducted to identify contamination clusters, and Logistic regression models were used to estimate associations. Results are reported as odds ratios (ORs) with 95% confidence intervals (CIs). Urinary levels of Pb, Hg, As, Cd, and Ni were significantly higher among obese participants. In the fully adjusted logistic regression model, cadmium (Cd) (OR = 3.27; 95% CI: 1.54–6.96), mercury (Hg) (OR = 2.97; 95% CI: 1.04–8.43), and nickel (Ni) (OR = 1.10; 95% CI: 1.05–1.17) showed significant associations with obesity. For drinking water, mercury (Hg) (OR = 30.24; 95% CI: 2.32–393.43), arsenic (As) (OR = 5.09; 95% CI: 1.16–22.19), chromium (Cr) (OR = 1.25; 95% CI: 1.08–1.45), and nickel (Ni) (OR = 1.16; 95% CI: 1.07–1.26) demonstrated similar associative patterns. Spatial analysis revealed significant geographic clustering of metals, particularly for As and Cr. These results suggest a possible association between chronic exposure to specific heavy metals via drinking water and the likelihood of obesity. The spatial overlap between water contamination and obesity indicates a geographic association, generating the hypothesis that local water quality may represent a relevant environmental exposure pathway requiring further investigation. Further longitudinal research is warranted to explore this potential connection.