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

AX6-90
Table AX6-4.2 (cont’d). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period Study Description Pb Measurement Findings, Interpretation
Asia (cont’d)
Chia et al. (1994b)
Study location not
provided; authors
from Singapore
1982-1992 (blood Pb
measurements
obtained every 6 mos
over this time)
Chia et al. (1994c)
Singapore
Study location not
provided; authors
from Singapore
1982-1992 (blood Pb
measurements
obtained every 6 mos
over this time)
128 Pb workers.
152 control workers without Pb or cadmium exposure.
Renal outcomes = total NAG, NAG-B isoenzyme
(released with lysosomal breakdown assoc with cell
membranes, thought to indicate proximal tubular cell
toxicity), NAG-A (released by exocytosis).
Cross-sectional outcomes but longitudinal exposure data.
63 Pb workers of >6 mos work duration (median = 3 yrs).
91 Pb workers of 40, 50, and 60 µg/dL.
NAG not different in exposed compared to control
workers.
After adjustment for race, recent change in blood Pb
was significantly associated with all NAG outcomes
(standardized partial regression coefficients ranged
from 0.31 for NAG-A to 0.64 for total NAG; neither
SE nor CI provided).
In contrast, current blood Pb was inversely associated
with NAG-A and NAG-B separately but, oddly, not
with total NAG. Authors do not comment on these
inconsistencies.
NAG not associated with cumulative Pb dose.
Strengths = longitudinal exposure data.
Limitations = data analysis clarity and adjustment.
Urinary BB-50 higher in exposed compared to recent
hire “control” workers. Time integrated blood Pb,
number of times blood Pb >40 µg/dL, and relative
change in recent blood Pb were associated with
urinary BB-50.
Strengths = longitudinal exposure data.
Limitations = data analysis content (Pb dose means not
reported), clarity and adjustment.