Urinary cadmium levels predict lower lung function in current and former smokers: data from the Third National Health and Nutrition Examination Survey.
BACKGROUND: A study was undertaken to determine the relation between urinary cadmium levels and lung function in a nationally representative cohort of current, former, and never smokers in the US. Urinary cadmium levels reflect the total body burden of cadmium. METHODS: The following data from the Third National Health and Nutrition Examination Survey were analysed: urinary cadmium (adjusted for urinary creatinine), lung function, sex, race/ethnicity, age, education level, job category, body mass index, serum cotinine level, and smoking history. Linear regression models were developed to predict lung function using urinary cadmium as the main predictor, adjusting for other covariates and stratified by smoking status. RESULTS: Data were available on 16 024 adults. Current smokers had higher mean (SE) urinary cadmium/creatinine levels (0.46 (0.01) micro g/g) than former (0.32 (0.01) micro g/g) or never smokers (0.23 (0.01) micro g/g). Higher levels of urinary cadmium were associated with significantly lower forced expiratory volumes in 1 second (FEV(1)) in current (-2.06%, 95% confidence interval (CI) -2.86 to -1.26 per 1 log increase in urinary cadmium) and former smokers (-1.95%, 95% CI -2.87 to -1.03) but not in never smokers (-0.18%, 95% CI -0.60 to 0.24). Similar results were obtained for forced vital capacity (FVC) and FEV(1)/FVC. CONCLUSIONS: Cadmium, which is known to cause emphysema in occupational settings, may also be important in the development of tobacco related lung disease.