Moderate selenium alleviates the pulmonary function impairment induced by cadmium and lead in adults: A population-based study

Selenium (Se) has been reported to have an antagonistic effect on heavy metals in animals. However, there is no epidemiological study investigating whether Se could protect against the pulmonary toxicity of Cadmium (Cd) and Lead (Pb). Data was collected from the 2011–2012 National Health and Nutrition Examination Survey (NHANES) cycle. Pulmonary function was assessed by Forced Vital Capacity (FVC), Forced Expiratory Volume 1st Second (FEV₁) and FEV₁/FVC. Blood concentrations of Cd, Pb, and Se were measured using inductively coupled plasma mass spectrometry. Linear regression, restricted cubic splines, and quantile-based g-computation (qgcomp) were performed to evaluate the individual and joint associations of Cd and Pb with pulmonary function and whether Se modified these associations. In the adjusted multi-metal model, every 1-unit increase in Cd, FEV₁, FVC, and FEV₁/FVC decreased by 76.437 mL (95 % CI: −110.928 to −41.947), 42.719 mL (95 % CI: −84.553 to −0.885), and 0.012 (95 % CI: −0.016 to −0.007), respectively. Meanwhile, FEV₁ decreased by 9.37 mL (95 % CI: −18.61 to −0.13) for every 1 unit increase in Pb. Furthermore, we found an inverted U-shape association between Se and lung function, and participants in the second quartile Se group had the highest increases in FEV₁ and FVC compared with participants in the lowest quartile. Qgcomp model also revealed that the toxic metal mixture (Cd and Pb) exhibited a significant inverse association with FEV₁ and FEV₁/FVC. Furthermore, we found that the inverse association of Pb and Cd, either alone or in combination, with pulmonary function first diminished with increasing Se levels but was re-enforced when blood Se concentrations were in the highest quartile. Our results indicated that moderate Se attenuated the harmful effects of Cd and Pb on lung function.