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

AX6-130
Table AX6-5.1. Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period Study Description Pb Measurement Findings, Interpretation
Meta-analysis
Nawrot et al. (2002)
31 U.S. and European
studies, community
and occupationally
exposed, published
between 1981 and
2001.
48 different groups, 32 of which
were only of men, 15 of which were
only of women, and one studying
both sexes. Total meta-analysis
N > 58,490. Age ranged from 15 to
93 yrs, depending on the study.
Two methods of meta-analysis were
used, subject-weighted and nonweighted,
using study-reported
effect sizes and standard errors,
transformed from the original study
specification of blood Pb (linear,
logarithmic, or blood Pb group) to a
single effect size for doubling of
blood Pb. Also did analyses
stratified by race and sex.
Mean blood Pb concentration
across studies ranged from
2.3 to 63.8 µg/dL. Total
range of blood Pb across
studies was 0 to 97.9 µg/dL.
Each doubling of blood Pb was associated with a significant 1.0 mm Hg
(95% CI: 0.5, 1.4) increase in systolic blood pressure and a significant 0.6
mm Hg (95% CI: 0.4, 0.8) increase in diastolic blood pressure. Stated that
differences in Pb effect were not statistically different between sexes, but did
not describe test nor give statistics other than p-values. Presented black and
white differences as a trend for blacks to be “more susceptible than whites,”
but presented no tests.
Statistically examined assumptions of homogeneity of effect and found no
significant heterogeneity. Tested for publication bias (statistically significant
results tend to be published more than non-significant results) and found no
evidence. Found no significant effects of removing one study at a time in
sensitivity analysis. It appears that the presented results of effect sizes and
confidence intervals were calculated by the subject-weighted method, but this
was not made explicit. Included some studies that presented no Pb
coefficients or standard errors, assuming effect size of zero, though the
reported effect sizes without these studies did not appear to be different from
overall effect sizes. For studies using a linear Pb measure, effect sizes were
calculated by doubling the arithmetic mean blood Pb. If the concentrationresponse
curve for the Pb-blood pressure relationship was really better
characterized by a log-linear function, the authors’ use of studies with a linear
blood Pb term with high avg blood Pb led to over-estimation of the slope of
the relationship and those studies with low blood Pb avgs produced an underestimation
of the slope of the relationship.