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

AX6-50
Table AX6-3.4 (cont’d). Meta-analyses of Neurobehavioral Effects with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
Schwartz et al. (2002)
Letter to the Editor commenting on
shortcomings in the Goodman et al. (2002)
meta-analysis on studies of neurobehavioral
testing in workers occupationally exposed to
Pb.
Seeber et al. (2002) A comparison of the two meta-analyses
Meyer-Baron and Goodman) performed to
evaluate recommendations of a German BEI
of 40 µg/dL.
Graves et al. (1991) A meta-analysis on 11 case-control studies of
Alzheimer’s disease for occupational
exposure to solvents and Pb.
The six points regarding problems with the methodology included:
(1) no evaluation of quality of study design or statistical methods,
(2) data from poorly done and well done studies are combined,
(3) included 6 studies with no age adjustment and 3 with no
adjustment for education, (4) confounding of age and education
when addressed the variation across studies not discussed, (5) main
effect only examined exposed vs. nonexposed comparisons that are
known to have the lowest power, cannot evaluated dose-effect
relationships and have a tendency for selection bias, and (6) few of
the 22 studies included contributed to effect size.
Effect size calculated for 12 tests in two meta-analyses and 10 tests
from one meta-analyses found subtle impairments associated with
blood Pb between37 µg/dL and 52 µg/dL for Logical Memory,
Visual Reproduction, Simple Reaction Time, Attention Test d2,
Block Design, and Picture Completion, Santa Ana, Grooved
Pegboard and Eye-hand Coordination. Effect sizes related to age
norms between ~40 to 50 yrs. For example, !3 score on Block
Design = 10 to 15 yrs; !3.5 score on Digit Symbol = 10 yrs; !21 score
on Cancellation d2 = 10 yrs; and +5 to +6 on Trails A = 10 to 20 yrs.
This analyses concluded that both meta-analyses supported
recommendation for German BEI of 40 µg/dL.
Four studies had data for Pb exposure with a pooled analysis of
relative risks for occupational Pb of 0.71 (95% CI: 0.36, 1.41).
The exposure frequencies were 16/261 for the cases and 28/337 for
the controls.