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

AX6-40
Table AX6-3.3 (cont’d). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
Europe
H≅nninen et al. (1998)
Finland
Lucchini et al. (2000)
Italy
Fifty-four Pb battery workers were
stratified by those whose blood Pb never
exceeded 50 µg/dL (n = 26) (group 1)
and those who had higher exposure in the
past (n = 28) (group 2) to examine the
neuropsychological effects of current low
level blood Pb from higher blood Pb in
the past. Mean age group 1was 42 (9.3)
yrs, education 8 (1.7) yrs and yrs of
exposure 12 (6.7). Mean age group 2 was
47 (6.2) yrs, education 8 (1.0) yrs and yrs
of exposure 21 (6.9). Analysis included
partial correlations within the groups and
ANCOVA within group 1 divided at the
median TWA3 of 29 µg/dL.
66 workers in Pb manufacturing, mean
age 40 (8.6) yrs, mean education 8 ( 2.4)
yrs and mean exposure time 11 (9) yrs
and a control group of 86 with mean age
43 (8.8) yrs, mean yrs of education 9
(2.7) yrs. Group differences examined
and dose-effect relationship with
correlation and ANOVA.
Group 1
Mean IBL 330 µg·yr/dL
Maximum blood Pb 40 µg/dL
TWA 29 µg/dL
Tibial Pb 20 µg/g
Calcaneal Pb 79 µg/g
Group 2
Mean IBL 823 µg·yr/dL
Maximum blood Pb 69 µg/dL
TWA 40 µg/dL
Tibial Pb 35 µg/g
Calcaneal Pb 100 µg/g
IBL, TWA and maximum
blood Pb were also calculated
for the previous 3 yrs with a
median TWA3 of 29 µg/dL
Pb workers
Mean (SD) blood Pb 28
(11) µg/dL
Mean (SD) IBL 410
(360.8) µg·yr/dL
Mean (SD) TWA 32
(14.1) µg/dL
Mean (SD) yrs exposed
11(8.1)
Control
Mean (SD) blood Pb 8
4.5) µg/dL
Partial correlations controlling for age, sex and education in group 1
found block design, digit symbol, digit span, similarities, Santa Ana 1
and memory for design significantly associated with recent measures
of exposure and embedded figures with maximum blood Pb. In group
2 embedded figures, digit symbol, block design, and associative
learning were associated with IBL and /or maximum blood Pb.
Calcaneal Pb was weakly associated with digit symbol, digit symbol
retention, and synonyms. There was no association with tibial Pb in
either group. Group 1 divided at the median TWA3 of 29 µg/dL
found the high group had lower scores for visuospatial and
visuoperceptive tasks (digit symbol, embedded figures and memory
for design). Overall past high exposure, blood Pb >50 µg/dL, had the
greatest effect on tests requiring the encoding of complex visually
presented stimuli. The authors conclude that the effect of Pb on brain
function is better reflected by history of blood Pb than content of Pb
in bone.
No association with neuropsychological tests (addition, digit span,
finger tapping symbol digit and motor test from Luria) and blood Pb,
TWA or IBL were found. Blood Pb and visual contrast sensitivities at
the high frequencies were significantly associated for the entire group.
Blood Pb and serum prolactin in the whole group was significantly
associated. Increased prolactin secretion occurs with a variety of
neurotoxins and reflects impaired dopamine function in the pituitary.
The estimated threshold for a significant increase of high prolactin
levels was at a blood Pb of 10 µg/dL.