ASSOCIATION OF BLOOD LEAD TO BLOOD-PRESSURE IN MEN AGED 55YEARS TO 75-YEARS - EFFECT OF SELECTED SOCIAL AND BIOCHEMICAL CONFOUNDERS

The association of blood lead (B-Pb) concentration to blood pressure was investigated in men aged 55 to 75 years living in the Rome area, who had no history of exposure to lead in the workplace and who participated between 1989 and 1990 in an epidemiologic survey for coronary heart disease (New Risk Factor Project). Of the 1856 individuals eligible for the study, 59 were excluded from analyses because not all relevant data were available, and 478 were excluded because they were treated for hypertension. In the remaining subjects (n = 1319) the median B-Pb concentration was 113 mu g/l (range: 40-442 mu g/l). Systolic blood pressure (SEP) averaged 140 +/- 18 (standard deviation) mm Hg (range 98-220) and diastolic blood pressure (DBP) 84 +/- 9 mm Hg (range 56-118). Median B-Pb values increased significantly from 111 mu g/l in subjects with normal blood pressure in = 668) to 113.5 mu g/l in subjects with borderline high blood pressure in = 373) and to 120 mu g/l in subjects with increased blood pressure (n = 278). After log-normal conversion of B-Pb, the linear correlation coefficient between In[B-Pb(mu g/l)] and both SEP and DBP was statistically significant (r = 0.1332, P <0.001 and r = 0.0737, p = 0.007, respectively). The linear regression coefficient was 6.8 mm Hg/In(mu g/l) for SEP and 1.8 mm Hg/ln/mu g/l) for DBP. Multiple regression analyses revealed that, after correction for body mass index (BMI), age, heart rate, skinfold thickness, serum lipids and glucose levels, blood lead was still a significant predictor of increased SEP and DBP. The adjusted regression coefficient was 5.6 mm Hg/ln(mu g/l) for SEP and 7.7 mm Hg/ln/mu g/l) for DBP. In further analyses subjects were divided, according to alcohol consumption, into drinkers (n = 1068) and nondrinkers (n = 252). Among nondrinkers the median B-Pb levels was 97 mu g/l (2.5th and 97.5th centiles 55-781 mu g/l) and SEP and DBP averaged 138 +/- 17 and 84 +/- 9 mm Hg, respectively. No significant relationship between In[B-Pb] and blood pressure was found. In drinkers the median B-Pb level was 117 mu g/l (2.5th and 97.5th centiles: 63-252 mu g/l) and SEP and DBP averaged 141 +/- 18 and 84 +/- 9 mm Hg, respectively. The linear. regression coefficient was 7.5 mm Hg/ln(mug/l) for SEP and 2.6 mm Hg/ln(mu g/l) for DBP. in multiple stepwise regressions including BMI, age, heart rate, smoking, skinfold thickness, serum lipids, and glucose levels as covariates--the partial correlation coefficient of systolic and diastolic blood pressure with In[B-Pb] remained statistically significant. The adjusted regression coefficients were 5.6 mm Hg/ln(mu g/l) for SEP and 2.5 mm Hg/ln(mu g/l) for DBP. These findings indicate that a slight to moderate positive relationship exists between blood pressure and blood lead concentrations in male drinkers aged 55 to 75 years.