A Prospective Study of Bone Lead Concentration and Death From All Causes, Cardiovascular Diseases, and Cancer in the Department of Veterans Affairs Normative Aging Study

Abstract

Background— Blood lead concentration has been associated with mortality from different causes in several studies. Many effects of lead exposure that might increase risk of death are likely to result from cumulative exposure, for which bone lead is a better biomarker than blood lead. The association between bone lead levels and mortality has not been explored. Methods and Results— We prospectively assessed the association between both blood lead and bone lead, analyzed with the use of K-shell x-ray fluorescence, and mortality among 868 men in the Normative Aging Study. We identified 241 deaths over an average of 8.9 (SD=3.9) years of follow-up. We calculated adjusted hazard ratios and 95% confidence intervals using Cox proportional hazards. Compared with the lowest tertile of patella bone lead, the fully adjusted hazard ratios in the highest tertile for all-cause, cardiovascular (n=137 deaths), and ischemic heart disease (n=62 deaths) mortality were 1.25 (95% confidence interval, 0.82 to 1.92), 1.42 (95% confidence interval, 0.80 to 2.51), and 1.87 (95% confidence interval, 0.77 to 4.53), respectively. Results were similar for tibia lead. Bone lead was not associated with cancer, and blood lead was not associated with any mortality category. Conclusions— We found bone lead to be associated with a slight increase in all-cause and cardiovascular mortality in an environmentally exposed population with low blood lead levels, but this did not reach statistical significance. This study suggests that cumulative lead exposure from prior decades of high environmental exposures may affect risk of death despite recent declines in environmental lead exposure, but studies with more follow-up are needed.