Nov. 23, 2009 -- Prenatal exposure to tobacco smoke and childhood exposure
to lead are linked to increased risk of attention deficit hyperactivity
disorder (ADHD) in children, a new study
The study is published in the December issue of Pediatrics.
Researchers led by Tanya E. Froehlich, MD, MS, of the department of
pediatrics at Cincinnati Children's Hospital Medical Center, analyzed data of
prenatal tobacco and childhood lead exposure in the 2001-2004 National Health
and Nutrition Examination Survey, a representative sample of U.S. children aged
8 to 15.
Prenatal tobacco exposure was measured by reports of cigarette use during pregnancy, and childhood lead exposure was assessed by
The researchers say they found that young people exposed prenatally to
tobacco smoke were 2.4 times more likely to have ADHD, and that those with
blood levels in the top third of the population had a 2.3-fold increased
likelihood of ADHD
The combined effect from both toxicants was even greater. Children with both
exposures had a more than eightfold increased chance of having ADHD, compared
to youths who weren't exposed to either, the researchers say.
The authors say their study is the first to determine the independent
effects of tobacco smoke and lead on ADHD in a nationally representative
sample, and contend it provides the first estimate of joint effects of the two
The researchers examined data on 2,588 youngsters from the National Health
and Nutrition Examination Survey 2001-2004 and 8.7% met criteria for diagnosis
with ADHD. "Our findings suggest that reduction of toxicant exposures may be an
important avenue for ADHD
prevention and they underscore the enormous burden that may be associated
with continued exposure to tobacco and lead,'' the researchers conclude.