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

AX6-139
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)
Rothenberg et al.
(1999)
U.S.-Los Angeles
1995-1998
Rothenberg et al.
(2002a)
U.S.-Los Angeles
1995-2001
1188 immigrants and 439 nonimmigrants,
from 15 to 43 yrs, all women in 3rd
trimester of pregnancy. Multiple
regression models of natural log blood Pb
on systolic and diastolic blood pressure
with all covariates forced into models.
Covariates selected from larger set based
on significant univariate or bivariate tests.
668 women, 15 to 44 yrs, studied in 3rd
trimester pregnancy and again a mean of
10 wks postpartum. Exclusion criteria
were diabetes, renal or cardiovascular
disease, extreme postnatal obesity
(BMI >40), and subjects using stimulant
drugs. Multiple linear regression models
of natural log blood Pb, tibia and
calcaneus Pb on systolic and diastolic
blood pressure with all covariates and all
Pb variables forced into model. Separate
models for 3rd trimester and postpartum,
excluding all women with hypertension
(see below) during each specific period.
Logistic regression for hypertension
(systolic ∃140 mm Hg or diastolic ∃90),
specific to 3rd trimester and postpartum
periods with the same covariates and Pb
variables.
Geometric mean (SD)
blood Pb:
Immigrants: 2.3 µg/dL
(1.4)
Non-immigrants:
1.9 µg/dL (1.3)
Geometric mean blood
Pb (SD):
3rd trimester:
1.9 µg/dL (1.7)
Postpartum: 2.3 µg/dL
(2.0)
Tibia mean Pb (SD):
8.0 µg/g (11.4)
Calcaneus mean Pb
(SD):
10.7 µg/g (11.9)
Natural log blood Pb, age, BMI, coffee drinking, iron supplementation, and job stress
were entered as a block without regard to significance in linear multiple regression
models of systolic and diastolic blood pressure stratified by immigration status.
Increased blood Pb was significantly associated with increased blood pressure only in
immigrants. Each natural log unit increase in blood Pb was associated with a
1.7 mm Hg (95% CI: 0.7, 2.8) increase in systolic blood pressure and a 1.5 mm Hg
(95% CI: 0.5, 1.9) increase in diastolic blood pressure in immigrants.
Used and reported model diagnostic tests, as evidenced by the use of standard error
calculations robust to residual heteroscedasticity. Stated reasons for stratification on
immigrant status were significant differences between the two groups in blood Pb,
blood pressure, age, BMI, and education. Did not statistically test difference in Pb
coefficients between the immigration strata. Did not correct for potential non-linearity
in age effects on blood pressure.
Multiple linear regression models for normotensives adjusted for postnatal
hypertension (3rd trimester model only), BMI, age, parity, smoking, alcohol,
immigrant status, and educational level plus all three Pb indices. Only calcaneus Pb
was associated with blood pressure in 3rd trimester models. Every 10 µg/g increase in
calcaneus Pb was associated with 0.70 mm Hg (95% CI: 0.04, 1.36) increase in
systolic blood pressure and a 0.54 mm Hg (95% CI: 0.01, 1.08) increase in diastolic
blood pressure. In postpartum models, natural log blood Pb was the only variable
statistically associated with blood pressure. Every natural log unit increase in blood
Pb was associated with !1.52 mm Hg (95% CI: !2.83, !0.20) decrease in systolic
blood pressure and a −1.67 mm Hg (95% CI: !2.85, !0.50) decrease in diastolic blood
pressure.
In logistic models, only calcaneus Pb was significantly associated with increased odds
for hypertension. Each 10 µg/g increase in calcaneus Pb was associated with an OR =
1.86 (95% CI: 1.04, 3.32) of 3rd trimester hypertension. None of the Pb variables
was associated with postpartum hypertension.
Models did not use age-squared covariate. Models did not use repeated measures
statistics. No statistical comparisons between 3rd trimester and postpartum models.
Model diagnostic tests reported.