Bone lead and blood lead levels in relation to baseline blood pressure andthe prospective development of hypertension - The Normative Aging Study

Between 1991 and 1997, the authors studied 833 participants of the Normativ e Aging Study in a substudy of bone lead levels (measured by K-shell x-ray fluorescence), blood lead levels, and hypertension. Among these subjects, 3 37 were classified as normotensive, and 182 and 314 were classified as havi ng borderline and definite hypertension, respectively, at baseline. These b one and blood lead levels were typical of those of community-exposed men. A mong the 519 subjects with no history of definite hypertension at baseline, cross-sectional analyses revealed positive associations between systolic b lood 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 d efinite hypertension were reported. Baseline bone lead levels were positive ly associated with incidence of hypertension. In proportional hazards model s that controlled for age, age squared, body mass index, and family history of hypertension, an increase in patella (trabecular) lead from the midpoin t of the lowest quintile to that of the highest quintile was associated wit h 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 s upport the hypothesis that cumulative exposure to lead, even at low levels sustained by the general population, may increase the risk of hypertension.