Association of blood lead concentrations with mortality in older women: a prospective cohort study

Background: Blood lead concentrations have been associated with increased risk of cardiovascular, cancer, and all-cause mortality in adults in general population and occupational cohorts. We aimed to determine the association between blood lead, all cause and cause specific mortality in elderly, community residing women. Methods: Prospective cohort study of 533 women aged 65-87 years enrolled in the Study of Osteoporotic Fractures at 2 US research centers (Baltimore, MD; Monongahela Valley, PA) from 1986-1988. Blood lead concentrations were determined by atomic absorption spectrometry. Using blood lead concentration categorized as < 8 mu g/dL (0.384 mu mol/L), and >= 8 mu g/dL (0.384 mu mol/L), we determined the relative risk of mortality from all cause, and cause-specific mortality, through Cox proportional hazards regression analysis. Results: Mean blood lead concentration was 5.3 +/- 2.3 mu g/dL (range 1-21) [0.25 +/- 0.11 mu mol/L (range 0.05-1.008)]. After 12.0 +/- 3 years of > 95% complete follow-up, 123 (23%) women who died had slightly higher mean (+/- SD) blood lead 5.56 (+/- 3) mu g/dL [0.27(+/- 0.14) mu mol/L] than survivors: 5.17(+/- 2.0) [0.25(+/- 0.1) mu mol/L] (p = 0.09). Women with blood lead concentrations = 8 mu g/dL (0.384 mu mol/L), had 59% increased risk of multivariate adjusted all cause mortality (Hazard Ratio [HR], 1.59; 95% confidence interval [CI], 1.02-2.49) (p = 0.041) especially coronary heart disease (CHD) mortality (HR = 3.08 [CI], (1.23-7.70)(p = 0.016), compared to women with blood lead concentrations < 8 mu g/dL(< 0.384 mu mol/L). There was no association of blood lead with stroke, cancer, or non cardiovascular deaths. Conclusion: Women with blood lead concentrations of = 8 mu g/dL (0.384 mu mol/L), experienced increased mortality, in particular from CHD as compared to those with lower blood lead concentrations.