Bone lead and blood lead levels in relation to baseline blood pressure and the prospective development of hypertension: the Normative Aging Study.

Between 1991 and 1997, the authors studied 833 participants of the Normative Aging Study in a substudy of bone lead levels (measured by K-shell x-ray fluorescence), blood lead levels, and hypertension. Among these subjects, 337 were classified as normotensive, and 182 and 314 were classified as having borderline and definite hypertension, respectively, at baseline. These bone and blood lead levels were typical of those of community-exposed men. Among the 519 subjects with no history of definite hypertension at baseline, cross-sectional analyses revealed positive associations between systolic blood pressure and bone lead levels. Of the 474 subjects who were free from definite hypertension at baseline and had follow-up data, 74 new cases of definite hypertension were reported. Baseline bone lead levels were positively associated with incidence of hypertension. In proportional hazards models that controlled for age, age squared, body mass index, and family history of hypertension, an increase in patella (trabecular) lead from the midpoint of the lowest quintile to that of the highest quintile was associated with a rate ratio of definite hypertension of 1.71 (95% confidence interval: 1.08, 2.70). No association was found with blood lead level. These results support the hypothesis that cumulative exposure to lead, even at low levels sustained by the general population, may increase the risk of hypertension.