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

AX6-52
Table AX6-3.5 (cont’d). Neurophysiological Function and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
Asia
Schwartz et al.
(2001a)
South Korea
1997-1999
Schwartz et al. (2005)
South Korea
1997-2001
804 workers from 26 different Pb using
facilities and 135 controls with a mean age of
40 ( 10.1) and 35 (9.1) yrs respectively, job
duration of 8 (6.5) and 9 (5.3) yrs
respectively, and education level 42 % and
69% completed high school respectively had
comparable alcohol and smoking use. Linear
regression used to compare vibration
threshold in Pb exposed and controls
controlling for potential confounders.
Longitudinal decline in neurobehavioral
performance examined in 576 of the above
group of Pb exposed workers who completed
3 visits at one yr intervals.
Mean age at baseline was 41 (9.5) yrs and
job duration 9 (6.3) yrs and 76% were men.
Compared to non-completers Pb workers
who completed 3 visits were 3.3 yrs older,
baseline mean blood Pb was 2.0 µg/dL
lower, on the job 1.6 yrs longer, 24% women
vs. 10% of noncompleters, and usually had
less than high school education. Models
examined short-term vs. long-term effects.
Final model had current blood Pb, tibia bone
Pb and longitudinal blood Pb and covariates.
Pb-exposed workers
Mean (SD) blood Pb
32 (15) µg/dL
Mean (SD) tibia bone Pb
37 (40.3) µg/g
Mean (SD) DMSAchelatable
Pb
186 (208.1) µg (4 h
collection)
Baseline mean (SD) blood
Pb 31 (14.2) µg/dL
Mean (SD) tibia Pb 38
(43) µg/g
After adjustment for age, gender, education and height, tibia Pb but
not blood Pb was significantly associated with poorer vibration
threshold in the dominant great toe but not the finger (∃ = !0.0020
[SE 0.0007], p < 0.01). These results contrast with those for
neurobehavioral measures (see above) performed in the same study
where tibial Pb was not a predictor of performance.
After adjustment for age, visit number, education, gender, height
(for vibration) and BMI (for grip strength and pinch) vibration
threshold in the dominant great toe and not the finger was associated
with tibia Pb (∃ = !0.0006 [95% CI: !0.0010, !0.0002]) and
longitudinal blood Pb (∃ = !0.0051 [95% CI: !0.0078, !0.0024])
in one model and blood Pb (∃ = !0.0019 [95% CI: !0.0039, 0.0001])
in another model.