Exposure to hazardous heavy metals such as cadmium and lead has been associated with several chronic diseases. Heavy metal exposure may contribute to increased oxidative stress and inflammation in the lungs, resulting in tissue destruction manifesting clinically as obstructive lung disease (OLD). We aimed to evaluate the association between serum cadmium and lead concentration and OLD.
Pooled cross-sectional data from the National Health and Nutrition Examination Survey 2007-2010 were used. OLD was defined as an FEV1/FVC ratio < 0.7 by spirometry. Active smokers were defined as self-reported current smokers or those with measured serum cotinine ≥ 10 ng/mL. Serum cadmium and lead levels were measured using mass spectrometry.
The prevalence of OLD was 12.4% (95% CI, 10.2%-13.6%). The mean (SE) cadmium levels in the OLD group were significantly higher in comparison with normal control subjects (0.51 [1.04] vs 0.33 [1.02], P < .001). Similarly, mean (SE) serum lead concentration was significantly higher in the OLD group compared with the control population (1.73 [1.02] vs 1.18 [1.0], P < .001). The association between OLD and smoking was significantly attenuated after adjusting for serum cadmium concentration. In addition, we demonstrated a progressive increase in serum cadmium concentrations with worsening FEV1 % predicted values among smokers in our study population.
In a large representative sample of the US population, we demonstrated a significant association between OLD and serum cadmium and lead concentrations. Cadmium appeared to partially mediate the association between smoking and OLD. A dose-response effect between increasing cadmium concentration and progressively worsening lung function was observed in smokers.