Relationship between levels of five heavy metals in whole blood and visceral adipose tissue in adolescents in the United States, 2011-2018

Objective To investigate the associations of whole blood levels of five heavy metals, including cadmium (Cd), lead (Pb), manganese (Mn), mercury (Hg), and selenium (Se), with the accumulation of visceral adipose tissue (VAT).

Methods Based on the 2011-2018 National Health and Nutrition Examination Survey database, a population-based cross-sectional study involving 4 668 adolescents aged 8-19 years in the United States (U.S.) was conducted. Generalized linear regression and restricted cubic splines were applied to model the linear and non-linear relationships between whole-blood heavy metal levels and VAT accumulation, respectively. In addition, stratified analyses were performed according to age, the body mass index (BMI), education levels, and the family poverty-income ratio.

Results The geometric mean blood concentrations of Cd, Pb, Mn, Hg, and Se of the U.S. adolescents from 2011 to 2018 were 0.13 μg/L, 0.53 μg/dL, 10.34 μg/L, 0.41 μg/L, and 183.67 μg/L, respectively, and the median VAT mass was 186.89 g. The distribution of VAT mass differed significantly by gender. In male adolescents, blood Pb levels were negatively associated with VAT mass (β=-0.037, 95% confidence intervalCI: -0.052 to -0.021), while in female adolescents, blood Cd levels were positively associated with VAT mass (β=0.041, 95%CI: 0.004 to 0.077). Whole blood Mn levels were significantly associated with VAT mass in both males and females, with a stronger association in females (β for males=0.107, 95%CI: 0.079 to 0.136; β for females=0.238, 95%CI: 0.180 to 0.295). The RCS model revealed a J-shaped relationship between whole blood Cd levels and VAT mass, and a reverse J-shaped relationship between whole blood Pb levels and VAT mass in males.

Conclusion The levels of the five heavy metals in whole blood are associated with VAT mass in U.S. adolescents. The result can help understand the metabolic health risks posed by heavy metal exposure, but further research is needed to clarify the mechanism underlying the toxicity of heavy metals to VAT.