Associations of blood and urinary heavy metals with obesity risk among children: NHANES 2015-2020.

BACKGROUND: Childhood obesity is a growing global public health concern that significantly increases the risk of metabolic diseases in both childhood and adulthood. However, research on the impact of heavy metal exposure on childhood obesity remains limited. METHODS: In this cross-sectional study, data from the 2015-2020 National Health and Nutrition Examination Survey were analyzed using logistic regression, weighted quantile sum (WQS) regression, quantile-based g-computation (qgcomp), and Bayesian kernel machine regression (BKMR) to assess the independent and combined associations of five blood metals and eleven urinary metals with childhood obesity risk, with stratification by sex and age. RESULTS: Among 2016 children, 422 (20.9%) were diagnosed with obesity. In single-exposure models, blood cadmium (Cd), lead (Pb), manganese (Mn), and urinary Cd, Pb, cobalt (Co), cesium, antimony, and tungsten were significantly associated with obesity risk. WQS regression, qgcomp, and BKMR analyses consistently demonstrated a significant positive association between blood metal mixture exposure and obesity risk, with Mn showing the strongest association. Conversely, urinary metal mixture exposure was significantly negatively associated with obesity risk, with Cd, Pb, and Co showing the strongest negative associations. These associations were particularly pronounced among male children. CONCLUSIONS: Exposure to metal mixtures is significantly associated with obesity in U.S. children. Further research is needed to confirm these findings. IMPACT: First use of multiple statistical models to confirm the combined effects of metal mixtures on childhood obesity. Blood metal mixture exposure is positively associated with childhood obesity risk, with manganese showing the strongest association. Urinary metal mixture exposure, dominated by cadmium, lead, and cobalt, is significantly negatively associated with childhood obesity risk. Associations between metal exposure and childhood obesity risk are more pronounced in male children.