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

AX6-142
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)
Sokas et al. (1997)
U.S.-Maryland
1989-1990
Sorel et al. (1991)
U.S.-NHANES II
1976-1980
264 active or retired construction
workers, over 99% men, who were not
involved in Pb work at time of testing,
mean age (range) 43 yrs (18-79).
Multiple regression modeling of
systolic and diastolic blood pressure
adjusted for covariates of BMI, age,
hematocrit, erythrocyte
protoporphyrin, race, linear blood Pb
and a race-linear blood Pb interaction.
Method of covariate entry not made
explicit, though it appeared to be
forced.
2056 females, 2044 males, 473 blacks
and 3627 whites, from 18-74 yrs, were
used in survey design and weight
adjusted multiple linear regressions
stratified by sex, with separate models
for systolic and diastolic blood
pressure. Covariates included age,
BMI, race, and poverty income ratio
and linear blood Pb. Method of
covariate entry not specified but may
have been forced. Different covariate
groups were used for different models.
Primary test for the effect of race on
the Pb-blood pressure relationship was
to note the change in the race
coefficient in models with and without
the linear blood Pb variable.
Mean blood Pb
(range): 8.0 µg/dL
(1-30)
Age-adjusted
arithmetic mean
blood Pb:
Black female:
13.2 µg/dL (no
variance information
for any blood Pb)
White female:
12.1 µg/dL
Black male:
20.1 µg/dL
White male:
16.8 µg/dL
Linear blood Pb was not significantly related to either systolic or diastolic blood
pressure, though the race by linear blood Pb interaction was marginally significant
(p = 0.09). Each 1 µg/dL increase in blood Pb increased black systolic blood pressure
0.86 mm Hg (no SE or 95% CI reported) more than white systolic blood pressure.
Linear blood Pb term may not be appropriate. Small sample compromises
interpretation of non-significant results. By using erythrocyte protoporphyrin and
blood Pb in the same model, these two measures of Pb exposure may have been
confounded. Incomplete reporting of procedures and results. No model diagnostic
tests reported.
Linear blood Pb was significantly related only to diastolic blood pressure in males,
adjusting for age and BMI. For every 1 µg/dL blood Pb increase diastolic blood
pressure increased 0.13 mm Hg (95% CI: 0.04, 0.21). Adding race to the model with
and without linear blood Pb terms did not appear to change the race coefficient.
Adding poverty index to the models with and without blood Pb produced the same
small change in poverty index coefficient.
Linear blood Pb may not be appropriate. Only confidence intervals were used to
assess the significance of changes in race and poverty index coefficients across
models with and without Pb, instead of using interaction terms of these two variables
with Pb. Incomplete reporting of procedures and results. No model diagnostic tests
reported.