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

AX6-64
Table AX6-3.8 (cont’d). Occupational Exposure to Organolead and Inorganic Lead in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
United States (cont’d)
Stewart et al. (2002)
U.S.
Balbus et al. (1997)
U.S.
Balbus et al. (1998)
U.S.
From the above group of former organolead
workers 535 were re-examined twice or four
times over a four yr period. Also a
nonexposed control group of 118 had repeat
examinations. Mean age at first visit
exposed/controls 56 (7.4)/59 (7.0),
percentage with at least a high school
education 66/71.2.
222 organolead manufacturing workers,
mean age 44 (8.7) yrs and 62 nonexposed
referents, mean age 43 (10) yrs performed
simple visual reaction time (SVRT). Linear
regression examined relationship between Pb
exposure and mean RT, median RT and
standard deviation of RT after controlling for
covariates.
A second publication further examined the
above data for relationship of interstimulus
interval (ISI) and Pb exposure.
1st examination
Mean (SD) blood Pb 5
(2.7) µg/dL
Mean (SD) tibia Pb 14
(9.3) µg/g
Mean (SD) peak tibia Pb
23 (16.5) µg/g
Mean (SD) exposure duration
8 (9.7) yrs
Mean (SD) duration since last
exposure 16 (11.7) yrs
Mean (SD) blood Pb 20
(9.5) µg/dL
Mean (SD) peak urine Pb level
143 (130) µg/L
On 17 of 19 neurobehavioral tests, former organolead workers
demonstrated greater annual decline in adjusted test scores
compared to controls with significant differences for Rey complex
Figure copy, RAVLT Trial 1 and RAVLT recognition. Annual
declines in performance showed greater age-related change in Pb
workers compared to controls for block design, digit symbol,
serial digit learning, finger tapping and Trails A. Blood Pb did not
predict annual change scores but peak tibial Pb did for symbol
digit, Rey Complex Figure delayed recall, RAVLT trial 1,
RAVLT delayed recall, Purdue pegboard (1 measure) and the
Stroop. For these 6 tests it was determined that an increase of
15.7 µg/g bone mineral of peak tibia Pb was equivalent in its
effect on annual test decline to 5 more yrs of age at baseline.
Authors conclude that data supports ongoing cognitive decline
associated with past occupational exposure to Pb.
Same as above Short ISIs of 1-3 seconds had no relationship with Pb exposure
while ISIs of 4-6 seconds were significantly associated with blood
Pb (∃ = 0.06 [SE 0.02], p = 0.02 along with ISIs of 7-10 seconds
(∃ = 0.05 [SE 0.02], p = 0.03). ISIs 7-10 seconds with peak urine
Pb levels (∃ = 64.29 [SE 21.86], p < 0.01).