Association between 24-hour urinary cadmium and pulmonary function among community-exposed men: The VA Normative Aging Study

Background: High levels of cadmium exposure are known to cause emphysema in occupationally exposed workers, but little has been reported to date on the association between chronic environmental cadmium exposure and pulmonary function. Objective: In this study we examined the association between pulmonary function and cadmium body burden in a subcohort of the Normative Aging Study, a community-based study of aging. Methods: We examined 96 men who had cadmium measured in single 24-hr urinary specimens collected in 1994-1995 and who had one to three tests of pulmonary function between 1994 and 2002 (a total of 222 observations). We used mixed-effect models to predict pulmonary function based on individual 24-hr urinary cadmium output, adjusted for age, height, time elapsed from the baseline, and smoking status. We assessed effect modification by smoking status. Results: Among all subjects, a single log-unit increase in baseline urinary cadmium was inversely associated with forced expiratory volume in 1 sec (FEV₁) percent predicted [β = -7.56%; 95% confidence interval (CI) -13.59% to -1.53%]; forced vital capacity (FVC) percent predicted (β = -2.70%; 95% CI -7.39% to 1.99%), and FEV₁/FVC ratio (β = -4.13%; 95% CI -7.61% to -0.66%). In models including an interaction between urinary cadmium and smoking status, there was a graded, statistically significant reduction in FEV₁/FVC ratio across smoking status in association with urinary cadmium. Conclusions: This study suggests that chronic cadmium exposure is associated with reduced pulmonary function, and cigarette smoking modifies this association. These results should be interpreted with caution because the sample size is small, and further studies are needed to confirm our findings.