Lead, blood pressure, and cardiovascular disease in men.

Animal studies have demonstrated that relatively low doses of lead can produce modest elevations in blood pressure. During the past 10 y, many epidemiologic studies have examined the relationship between low-level lead exposure and blood pressure in humans. These studies were reviewed in a consensus conference, which concluded that the evidence supported the existence of a causal association; however, no formal meta-analysis has been conducted. Epidemiologic studies of blood lead and systolic blood pressure in males were analyzed in the present meta-analysis. A highly significant and moderately consistent association was found, i.e., decrease of blood lead from 10 mg/dl to 5 mg/dl associated with a decrease of 1.25 mm Hg (95% CI = 0.87-1.63 mm Hg). The association was robust to deletion of the most significant study or the addition of eight additional studies showing no effect. Given the strong animal data, which also implicate a mechanism (disturbance of calcium messenger system regulation of blood pressure) present in humans, the association should be considered causal.