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

AX6-58
Table AX6-3.6 (cont’d). Evoked Potentials and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
Asia (cont’d)
Hirata and Kosaka
(1993)
Japan
Murata et al. (1993)
Japan
41 Pb-exposed men from Pb-glass-based colors manufacturing
(n = 20), production of Pb electrode plates (n = 8), casting of Pbbronze
(n = 4) and casting of Pb pipes and plates (n = 9) had mean
age 41 yrs, mean duration of exposure 13 yrs. A battery of tests
administered including radial nerve conduction study,
electroretinogram (ERG), visual evoked potential (VEP),
brainstem auditory evoked potential (BAER), and short-latency
somatosensory evoked potential (SSEP). Comparison group of 39
unexposed used only for BAER analysis by Student’s t test.
Correlation and linear regression controlling for age examined the
relationship of Pb and the other variables.
22 gunmetal foundry workers with age range of 32 to 59 yrs and
work duration of 1 to 19 yrs and control group matched for age,
no chronic disease and no Pb exposure participated. No
significant difference between groups for age, height, skin
temperature, alcohol consumption, and yrs of schooling. The test
battery consisted of visual evoked potential (VEP), brainstem
auditory evoked potential (BAEP), short latency somatosensoryevoked
potential (SSEP), event related potential (P300) and EKG
R-R interval variability. Paired-sample t test examined for
differences between the matched groups. Dose-effect
relationships examined with partial correlation adjusting for age
and stepwise linear regression.
Mean (range) blood Pb
43 µg/dL (13-70)
Mean (range) TWA (based
upon previous 5 yrs)
43 µg/dL (13-70)
Mean (range) duration of
exposure 13 (0.6-29) yrs
Blood Pb 12 to 64 µg/dL
(no mean provided)
Significant partial correlation after adjusting for age
included TWA and radial motor conduction velocity,
blood Pb and sensory conduction velocity, exposure
duration and VEP, blood Pb and SSEP-N20.
Comparison of BAERs of 15 Pb exposed and 39
controls found interpeak interval III-V was
prolonged significantly. It is not clear why
comparison group only used for BAERs.
Considering the large number of variables examined
with three exposure terms some of the findings could
be by chance alone.
For VEPs, N75 and N145 were significantly
prolonged in the Pb exposed workers. N9-N13
interpeak latency of the SSEP was significantly
prolonged. BAEP latencies showed no significant
differences. P300 believed to reflect cognitive
function was prolonged in the Pb workers and
correlated with blood Pb, and PbU. Autonomic
nervous system effects were significantly diminished
for CV R-R and for a measure of parasympathetic
activity C-CVRSA. Fifty percent of the outcome
variables showed significant group differences but
there is limited dose effect for any outcome within
the exposed group. Small sample size limited
conclusions with 20 outcome variables and 8
biomarkers of Pb exposure.