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PRENATAL TOBACCO EXPOSURE, ELEVATED LEAD LINKED TO ADHD
High lead levels and prenatal exposure to
tobacco markedly increase children's risk for
attention deficit hyperactivity disorder
(ADHD), according to a new study that confirms
previous findings
(see related articles, Crime Times, 1996, Vol. 2, No. 4, Page 3
and Crime Times, 2006, Vol. 12, No. 3, Page 3).
ADHD, in turn, is a significant risk
factor for academic and career problems,
antisocial behavior, and substance abuse.
Joe Braun and colleagues analyzed data from
more than 4,000 children participating in the
National Health and Nutrition Examination
Survey (NHANES) for 1999-2002. Of these
children, 4.2% were diagnosed with ADHD and
were taking stimulant medications. The
researchers' analysis showed that "prenatal
tobacco exposure and blood lead concentration
were significant predictors of ADHD," while
postnatal tobacco exposure had no detectable
effect.
The researchers found that the effects of
prenatal tobacco exposure were more pronounced
for girls than for boys, with the risk
doubling for males but more than quadrupling
for females. While boys are normally at much
higher risk for ADHD than girls, Braun et al.
say, "When females are exposed to prenatal
tobacco smoke, their risk of ADHD becomes
equivalent to that of unexposed males."
The researchers also detected a significant
dose-response relationship between blood lead
levels and ADHD, even at low lead levels. They
note, "This result is consistent with previous
studies that have found cognitive deficits in
children with blood lead levels below 10
micrograms per deciliter [the currently
accepted safety threshold]."
Their data, the researchers say, "suggest
that prenatal tobacco exposure accounts for
270,000 excess cases of ADHD and lead exposure
accounts for 290,000 excess cases of ADHD in
U.S. children."
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"Exposures to environmental toxicants and
attention deficit hyperactivity disorder in
U.S. children," Joe Braun, Robert S. Kahn,
Tanya Froehlich, Peggy Auinger, and Bruce P.
Lanphear, Environmental Health
Perspectives, online publication, September
19, 2006. Address: Bruce Lanphear, Mail
Location 7035, 2800 Winslow Avenue, Cincinnati,
OH 45206, bruce.lanphear@cchmc.org.
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