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

AX6-91
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. (1995a)
Study location not
provided; authors
from Singapore
1982-1993 (blood Pb
measurements
obtained every 6 mos
over this time)
Chia et al. (1995b)
Study location not
provided; authors
from Singapore
1982-1993 (blood Pb
measurements
obtained every 6 mos
over this time)
137 Pb stabilizer workers.
Control group of 153 postal workers (older than Pb
workers).
Renal outcomes = serum creatinine, four h creatinine
clearance, serum ∃-2 microglobulin, serum α-1
microglobulin, urine albumin.
Longitudinal blood Pb data (mean of 4.5 measurements
per Pb worker).
128 Pb stabilizer factory workers.
93 unexposed control subjects (evaluated at preemployment
examination; all quit within 1 mo of hire).
Blood and urinary cadmium also measured on random
subset (40 controls and 31 Pb workers).
Renal outcomes = serum ∃-2 microglobulin and urinary α-
1 microglobulin, ∃-2 microglobulin, albumin, RBP.
Pb dose measures
(means or medians not stated)
Most recent blood Pb, time
integrated blood Pb index,
relative % change in recent
blood Pb, absolute change in
recent blood Pb, number of
times blood Pb level >40, 50,
and 60 µg/dL.
Mean recent blood Pb
32.6 µg/dL (workers)
9.0 µg/dL (controls)
Mean time integrated blood
Pb index
119.9 µg/dL Η yr (workers)
0.05 µg/dL Η yr (controls)
Mean relative change in
recent blood Pb
28.2 % (workers)
Mean absolute change in
recent blood Pb
6.4 µg/dL/yr (workers)
Number of times blood Pb
level >40, 50 and 60 µg/dL
In analysis of covariance modeling, adjusted for age and race,
mean serum α-1 microglobulin and urine albumin were
significantly higher in control compared to Pb workers.
Serum ∃-2 microglobulin was significantly higher in Pb
workers ≥30 yrs of age.
After adjustment for age, race, and smoking, prevalence rates
for abnormal values of serum creatinine and ∃-2
microglobulin were higher in the highest category of time
integrated blood Pb index in workers ∃30 yrs of age
(PRR = 3.8 [95% CI: 1.1, 13.3] and 10.3 [95% CI: 3.9,
26.9], respectively).
Strengths = longitudinal exposure data.
Limitations = data analysis content (Pb dose means not
reported), clarity and adjustment.
Only urinary α-1 microglobulin was significantly higher in Pb
workers compared to controls.
In multiple linear regression analysis, adjusted only for
ethnicity and smoking, at least one Pb measure was
significantly associated with each of the five renal outcomes.
Outcome Pb measure ∃ (95% CI)
U α-1 MG cum. blood Pb 0.10 (0.06, 0.14)
U α-1 MG # blood Pb >50 0.43 (0.04, 0.82)
U ∃-2 MG cum. blood Pb 0.05 (0.01, 0.09)
U RBP # blood Pb >50 0.35 (0.12, 0.59)
S ∃-2 MG # blood Pb >60 0.47 (0.29, 0.65)
U Alb # blood Pb >60 0.66 (0.13, 1.19)
Cadmium dose measures reportedly not significant in these
models (although power would have been reduced as
cadmium measured only in a subset).
Strengths = longitudinal exposure data.
Limitations = data analysis clarity and adjustment. Overlap
in populations between this study and earlier ones possible.