Blood lead below 0.48 micromol/L (10 microg/dL) and mortality among US adults

Blood lead levels above 0.48 micromol/L (10 microg/dL) in adults have been associated with increased risk of cardiovascular, cancer, and all-cause mortality. The objective of the present study was to determine the association between blood lead levels below 0.48 micromol/L and mortality in the general US population.

Blood lead levels were measured in a nationally representative sample of 13,946 adult participants of the Third National Health and Nutrition Examination Survey recruited in 1988 to 1994 and followed up for up to 12 years for all-cause and cause-specific mortality. The geometric mean blood lead level in study participants was 0.12 micromol/L (2.58 microg/dL). After multivariate adjustment, the hazard ratios (95% CI) for comparisons of participants in the highest tertile of blood lead (> or = 0.17 micromol/L [> or = 3.62 microg/dL]) with those in the lowest tertile (< 0.09 micromol/L [< 1.94 microg/dL]) were 1.25 (1.04 to 1.51; P(trend) across tertiles = 0.002) for all-cause mortality and 1.55 (1.08 to 2.24; P(trend) across tertiles = 0.003) for cardiovascular mortality. Blood lead level was significantly associated with both myocardial infarction and stroke mortality, and the association was evident at levels > 0.10 micromol/L (> or = 2 microg/dL). There was no association between blood lead and cancer mortality in this range of exposure.

The association between blood lead levels and increased all-cause and cardiovascular mortality was observed at substantially lower blood lead levels than previously reported. Despite the marked decrease in blood lead levels over the past 3 decades, environmental lead exposures remain a significant determinant of cardiovascular mortality in the general population, constituting a major public health problem.