Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX6-143
Table AX6-5.1 (cont’d). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period Study Description Pb Measurement Findings, Interpretation
United States (cont’d)
Sharp et al. (1990)
U.S.-San
Francisco, CA
1986
After exclusion of subjects under
treatment for hypertension, 249 male
bus drivers, 132 of whom were black,
age from 31 to 65 yrs, were used in
race stratified multiple regression
models of systolic and diastolic blood
pressure with covariate forced entry of
age, age-squared, BMI, caffeine use,
tobacco use, and natural log blood Pb.
Alcohol use was added in other
models. Other models stratified by
caffeine use.
Geometric mean (range)
blood Pb:
Black males: 6.5 µg/dL (3-21)
Non-black males:
6.2 µg/dL (2-15)
Significant log blood Pb effects were noted in blacks. In models excluding alcohol
use, for every one natural log unit increase of blood Pb, systolic blood pressure rose
7.53 mm Hg (95% CI: 0.86, 14.2) and diastolic blood pressure rose 4.72 mm Hg
(95% CI: 0.15, 9.29). Stratified by infrequent/frequent caffeine users, only black
infrequent caffeine users showed a significant response to blood Pb. For every one
natural log unit increase of blood Pb, systolic blood pressure rose 16.69 mm Hg (95%
CI: 3.83, 29.5) and diastolic blood pressure rose 10.43 mm Hg (95% CI: 1.26, 19.6).
Non-black blood pressure was decreased with increasing natural log Pb but was
marginally significant. In all non-black subjects, for every unit increase in natural log
blood Pb, systolic blood pressure decreased −5.71 mm Hg (95% CI: −12.0, 0.6).
Addition of alcohol to the models decreased all coefficients a small amount.
Progressive addition of age, BMI, caffeine, and tobacco, in that order, progressively
increased the coefficient of natural log blood Pb in models of systolic and diastolic
blood pressure in blacks. Removal of two black outliers did not materially change the
results for blacks.
No statistical tests for comparing stratified models, models with and without caffeine
use, effect of progressive addition of covariates, or addition of alcohol. Influence
diagnostics reported for detecting the two outlying subjects. No other diagnostic tests
reported. Small differences in text and table reports of the same coefficients. Small
sample size limits interpretation of non-significant results.