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

AX6-16
Table AX6-2.4 (cont’d). Effects of Lead on Academic Achievement in Children
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
Asia
Wang et al. (2002a)
Taiwan
Rabinowitz et al. (1992)
Taiwan
Middle East
Al Saleh et al. (2001)
Saudi Arabia
Design: Cross-sectional. 934 3rd graders living in
an urban industrial area of Taiwan. Outcome
variables were grades for Chinese (reading, writing),
mathematics, history, and natural science. Grades
were converted into individual class rankings to
avoid teacher bias. Limited data on medical and
sociodemographic covariates.
Design: Cross-sectional. Teachers of 493 children
in grades 1-3 filled out the Boston Teachers
Questionnaire (BTQ) to assess academic
performance and behavior. Sociodemographic and
medical covariate factors were assessed.
Class rank, as assessed by the teacher, was examined
in conjunction with blood Pb levels in 533 Riyadh,
Saudi Arabian girls (6-12 yrs of age). Extensive data
were collected on potentially confounding variables
including sociodemographic variables, early
developmental milestones and child health status.
Blood Pb at time of
evaluation
Blood Pb 5.5 (SD 1.9)
µg/dL
Tooth (dentin) Pb
Tooth Pb 4.6 (SD 3.5) µg/g
Blood Pb at time of testing
Blood Pb 8.1 (SD 3.5)
µg/dL
Following covariate adjustment, blood Pb was significantly
associated with lower class ranking in all academic
subjects. Major shortcoming of this study is lack of
control for potentially important covariates such as
parental IQ. However, the relatively low levels of
exposure in this sample and strength and consistency of the
reported relationships suggest that Pb may be playing some
role in lowering academic performance.
Prior to adjustment for covariates, girls with higher
exposures to Pb evinced a borderline significant trend for
reading difficulties while byes displayed significantly
increased difficulties with respect to activity levels and
task attentiveness. In logistic regression models that
include significant covariate factors, the tooth Pb terms
failed to achieve statistical significance. Authors conclude
that Pb levels found in the teeth of children in this
Taiwanese sample are not associated with learning
problems as assessed by the BTQ.
A significant inverse relationship between blood Pb levels
and rank percentile scores was observed after adjusting for
a number of demographic and socioeconomic variables.
When multiple regression models were fitted to a subset of
students with blood Pb levels below 10 µg/dL, class rank
percentile continued to show a statistically significant
association with blood Pb levels.