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

AX6-32
Table AX6-3.1 (cont’d). Neurobehavioral Effects Associated with Environmental Lead Exposure in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
United States (cont’d)
Weisskopf et al.
(2004b)
U.S.
Europe
Nordberg et al. (2000)
Sweden
466 men, mean age 70 yrs, in the VA
Normative Aging Study had 2 MMSE tests
3.5 yrs apart.
762 participants, mean age 88 yrs, in a study
of aging and dementia examined MMSE.
Used blood Pb as dependent and examined
contribution of covariates and MMSE.
Mean blood Pb 4 µg/dL
Mean patella bone Pb 23
µg/g
Mean tibia bone Pb 19 µg/g
Baseline mean MMSE score was 27 and mean change in MMSE
score over 3.5 yrs was 0.3. Change in MMSE associated with one
interquartile range increment for bone Pb and blood Pb found
relationship between patella Pb and change in MMSE was unstable
when patella Pb is ∃90 µg/g bone mineral. Examination of patella Pb
below this level found a greater inverse association with MMSE at
lower Pb concentrations (∃ = !0.25 [95% CI: !0.45, !0.05]). A similar
but weaker association existed for tibia Pb when values ∃67 µg/g
bone mineral were removed (∃ = !0.19 [95% CI: !0.39, 0.02]). There
was no association of MMSE change and blood Pb (∃ = !0.01 [95%
CI: !0.13, 0.11]). There was no interaction of age and bone Pb.
These are very high bone Pb levels for environmental exposure. The
biological plausibility of change in the MMSE over 3.5 yrs would
have been reinforced if the change by functional domain in the
MMSE was provided.
Mean blood Pb 3.7 µg/dL Mean MMSE 25 found no relation of blood Pb and MMSE. In this
population was fairly homogenous, all elderly Swedes, and the
likelihood of prior exposure to elevated Pb levels was low.