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

AX6-148
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
Europe (cont’d)
Maheswaran, et al.
(1993)
Europe-England-
Birmingham
1981
Menditto et al.
(1994)
Europe-Rome-
New Risk Factors
Survey
1989-1990
809 out of 870 workers, mean (SD)
age 43.3 (10.4) yrs, at an Pb acid
battery plant were used in the study.
Women and workers taking
antihypertensive medications were
excluded. Used multiple linear
regression analyses of systolic and
diastolic blood pressure, forcing age,
BMI, alcohol use, linear blood Pb, zinc
protoporphyrin, yrs of work exposure,
cigarette smoking as covariates.
1319 males, mean (range) age 63 (55-
75) yrs, not treated for hypertension,
were used in forward stepwise
multiple linear regression models of
systolic and diastolic blood pressure
with available covariates of age, BMI,
heart rate, serum high density
lipoprotein, non-high density
lipoprotein, triglycerides, glucose,
cigarette use, alcohol use, sum of five
skinfold thicknesses (triceps, biceps,
subscapular, suprascapular, and
suprailiac), and natural log
transformed blood Pb.
Geometric mean
(SD) blood Pb:
31.6 µg/dL (5.5)
Median (2.5th-97.5th
percentiles, range)
blood Pb: 11.3 µg/dL
(6.2-24.7, 4-44.2)
Linear blood Pb was not significant for either systolic or diastolic blood pressure.
Authors used two indices of Pb exposure in the same models. Over much of the studied
blood Pb range, zinc protoporphyrin was likely collinear with blood Pb. Linear blood Pb
may not be the appropriate metric to use in blood pressure models. Did not use age-squared
to adjust for non-linear relationship of blood pressure with age. Did not report model
diagnostics.
Only BMI, heart rate, and serum glucose were not simultaneously and significantly
correlated with both natural log blood Pb and blood pressure. In a systolic blood pressure
model adjusted for BMI, age, heart rate, high and non-high density lipoprotein, triglycerides,
glucose, and cigarettes, each unit increase in natural log blood Pb was significantly
associated with a 5.6 mm Hg (95% CI: neither SE nor CI stated) increase in blood pressure.
In a diastolic blood pressure model adjusted for BMI, heart rate, age, cigarettes, triglycerides,
and high density lipoprotein, each unit increase in natural log blood Pb was significantly
associated with a 1.7 mm Hg (95% CI: neither SE nor CI stated) increase in blood pressure.
In stratified models for alcohol drinkers (n = 1068) and non-drinkers (n = 251) only alcohol
drinkers showed significant natural log blood Pb associated blood pressure increase, with Pb
coefficients similar to those of the entire group.
Authors observed change in natural log blood Pb coefficient produced by successive addition
of covariates to models. In no case did the coefficients change by more than 30% after
addition of a covariate. Authors noted that wine was the predominant drink in alcohol users
and that the correlation between alcohol consumption and natural log blood Pb level was the
highest among all correlations reported (p < 0.001; correlation coefficient not stated).
No statistical tests were made to determine if the change in Pb coefficients with addition of
covariates was significant, nor were statistical tests made to determine if the Pb coefficients
in the alcohol use stratified models were significantly different. Small size of the nonalcohol
drinking group in stratified analysis precludes interpretation of non-significant
effects. Incomplete reporting of results. Paper published in a supplement issue reporting
meeting papers may indicate that it received less that the normal peer-review scrutiny for
published research articles. No model diagnostic tests were reported.