Urinary metals are associated with obesity in U.S. children and adolescents: A cross-sectional study

•The critical metals affecting obesity in children and adolescents are barium (Ba), thallium (Tl), cobalt (Co), cadmium (Cd), and lead (Pb).•Mixed metal exposure is negatively associated with obesity in children and adolescents.•There was no significant interaction between any 2 metal exposures and obesity.•Gender differences exist in mercury (Hg) exposure, with Hg negatively associated with obesity in females. Heavy metals are pervasive in the environment, and exposure to these metals may contribute to obesity in children and adolescents. We hypothesized that metal exposures are associated with obesity in children and adolescents. Data were drawn from children and adolescents aged 6 to 19 years from the 2007 to 2018 National Health and Nutrition Examination Survey. We employed weighted multivariate logistic regression and restricted cubic spline to explore the effects of individual metal exposures on obesity, and weighted quantile sum regression, quantile g-computed regression, and Bayesian kernel machine regression to explore the effects of mixed metal exposures on obesity. Subgroup analyses by gender were also performed. All models were adjusted for age, gender, race, poverty to income ratio, and serum cotinine. Among the 3,650 children and adolescents studied, 21.04% had obesity. Logistic regression revealed positive associations between barium (OR = 1.23, 95% CI: 1.07-1.40) and thallium (OR = 1.55, 95% CI: 1.23-2.15) with obesity, while cadmium (OR = 0.74, 95% CI: 0.61-0.89), cobalt (OR = 0.51, 95% CI: 0.41-0.62), and lead (OR = 0.70, 95% CI: 0.57-0.86) were negatively associated with obesity. Restricted cubic spline indicated a nonlinear relationship between lead and thallium and obesity. Quantile g-computed regression demonstrated that mixed metal exposure was negatively associated with obesity (OR = 0.50, 95% CI: 0.42-0.59). Subgroup analyses revealed a gender-specific effect for mercury (P for interaction = 0.03), which was negatively associated with obesity in females (OR = 0.83, 95% CI: 0.69-0.99). In conclusion, metal exposures are associated with obesity in children and adolescents, with gender differences. Our study examines the relationship between metal exposure and obesity in children and adolescents aged 6 to 19 years in the United States. We found that mixed metal exposure was negatively associated with obesity, identifying 5 critical metals: Ba, Cd, Co, Pb, and Tl. Among them, Ba and Tl showed a positive association with obesity, while