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

AX4-31
Table AX4-8 (cont’d). Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Reference, Study
Location, and
Period Study Description
United States (cont’d)
Hu et al. (2001)
Boston, MA
1991+
Oliveira et al. (2002)
Boston, MA
1991-98
Normative Aging Study. Aim to
determine if ALAD polymorphism is
associated with altered levels of lead
in bone and blood. Multivariate
linear regression models controlling
for age, education, smoking, alcohol
ingestion, and vitamin D intake.
Normative Aging Study.
To determine if seasonal fluctuations
in PbB levels are related to increased
mobilization of bone Pb stores during
the winter months. Measurements of
blood and bone Pb during the high
sun exposure months of May-August
(summer; n = 290); the intermediate
sun exposure months of March, April,
September, and October (spring/fall;
n = 283); and the low sun exposure
months of November-February
(winter; n = 191).
Lead Measurement (SD or range)
PbB in µg/dL, Bone Pb in µg/g Bone Mineral Findings, Interpretation
ALAD 1-1 (n = 608): PbB 6.3(±4.1), tibia 22.2
(±13.9), patella 32.2 (±19.9)
ALAD 1-2/2-2 (n = 118): PbB 5.7 (±4.2), tibia 21.2
(±10.9), patella 30.4 (±17.2)
ALAD 1- 1 genotype was associated with cortical
bone lead levels that were 2.55 µg/g (95% CI: 0.05,
5.05) higher than those of the variant allele carriers.
Mean PbB levels were slightly lower in summer
(5.8 ± 3.4 µg/dL) compared with winter (6.6 ± 4.7
µg/dL). Mean bone Pb levels were higher during the
summer than the winter months: 23.9 (±15.2) and
20.3 (±11.3) µg/g respectively for the tibia and
34.3 (±22.8) and 29.0 (±16.2) µg/g respectively for
patella.
No significant differences by genotype with respect
to Pb levels in trabecular bone or blood. In
stratified analyses and a multivariate regression
model that tested for interaction, the relationship
of trabecular bone Pb to PbB appeared to be
significantly modified by ALAD genotype, with
variant allele carriers having higher PbB levels, but
only when trabecular bone Pb levels >60 µg/g.
The authors suggest that the variant ALAD-2 allele
modifies lead kinetics possibly by decreasing lead
uptake into cortical bone and increasing the
mobilization of lead from trabecular bone.
Found a significant interaction between season and
bone Pb with bone Pb during the winter months
exerting an almost 2-fold greater influence on PbB
levels than during the summer months. The
authors attributed this to increased mobilization of
endogenous bone Pb stores arising potentially from
decreased exposure to sunlight, lower levels of
activated vitamin D and enhanced bone resorption.