Study shows lead poisoning leads to
behavioral problems in school age, urban children
after lead was banned from paint and gasoline, a new five-year study of
children from four U.S. cities shows that lead poisoning results not
only in lower IQ scores but also learning and behavioral problems in
school age urban children.
The study appears in the March issue of Pediatrics. Dr. Bo Cai,
an assistant professor in the Department of Epidemiology and
Biostatistics at USCís Arnold School of Public Health and one of the
lead authors on the report, said parents should remain concerned about
lead long after toddlerhood.
The analysis was based on data from 780 children exposed to high levels
of lead in four U.S. cities (Baltimore, MD.; Newark, NJ; Philadelphia,
PA and Cincinnati, OH). The researchers examined associations between
blood lead concentrations at different ages, IQ, and behavioral test
Although the blood lead concentration in 5-year-olds had no direct
effect on behavior, Dr. Cai said, seven-year-olds with higher levels of
the toxic metal in their blood were more likely to suffer IQ deficits,
and independently, they were also more likely to exhibit behavior
problems such as aggression, inattention and impulsivity -- an area that
has not received as much study.
For years parents have been urged to be vigilant about lead exposure in
very young children, but the study suggests that there is probably no
safe age for parents to be unconcerned about the danger of lead
That position is not withstanding the recommendations of the American
Academy of Pediatrics and the federal Centers for Disease Control and
Prevention which stopped recommending screening every U.S. child for
high lead levels a decade ago.
Children are at risk in an estimated 25 percent of U.S. homes that still
contain deteriorating lead paint, which was banned in 1978. Children
also are exposed when they play in yards contaminated by lead paint dust
or emissions from leaded gasoline which was phased out in the early
Besides Pediatrics, the study also was reported in The
and USA Today.
More details of the study:
The new study was part of a larger effort to test a chelating agent, a
type of medicine designed to filter lead from children's bodies. The
medicine did indeed reduce concentrations of lead in the blood, but it
did not have any measurable impact on intelligence or behavior.
The children's blood was tested starting at age 2; all measured between
20 and 44 micrograms per deciliter of blood, though the levels declined
somewhat as they got older. The federal guideline is 10 micrograms; many
health experts say even 10 is too high.
The children were given IQ and behavior evaluations at ages 5 and 7.
Behavior scores were based on lengthy questionnaires filled out by
teachers and parents.
For every increase of 10 micrograms per deciliter of blood, children
scored about five points worse on a 100-point scale that measures
"externalizing" behavior problems, such as aggression and acting out.
Also, for every 10-microgram increase, the children were nearly 11/2
times more likely to exhibit these types of problems.
The effect was present even after taking into account the fact that some
behavior problems could be the result of a lower IQ, said primary author
Aimin Chen, who is now at Creighton University. An effect on behavior
was evident even after authors controlled for poverty, ethnicity,
parental education, and whether the child had a single parent.
Cai joined the faculty at the Arnold School last August. Prior to
this, he worked as a research fellow in National Institute of
Environmental Health Sciences (NIEHS) of NIH. His work mainly
focuses on statistical methodology with applications in public health.
Cai is a member of the Research Consortium on
Children and Families (RCCF) and was recruited to USC as part a Faculty
Excellence Initiative coordinated by RCCF.