Children exposed to tobacco in utero and to lead during childhood are eight times more likely to be diagnosed with attention deficit/hyperactivity disorder (ADHD), according to the first study to examine the combined effects of these exposures in U.S. children. The study, “Association of Tobacco and Lead Exposures with Attention-Deficit/Hyperactivity Disorder,” published in the December issue of Pediatrics (appearing online Nov. 23), examined records of prenatal tobacco and childhood lead exposure in the 2001-2004 National Health and Nutrition Examination Survey, a cross-sectional, nationally representative sample of U.S. children ages 8 to 15. Prenatal tobacco exposure was measured by report of maternal cigarette use during pregnancy, and lead exposure was assessed by current blood lead levels. Children exposed prenatally to tobacco smoke were 2.4 times more likely to have ADHD, and those with blood lead levels in the top third of the population had a 2.3-fold increased likelihood of ADHD.

Furthermore, the combined effects of these toxicants are synergistic, and children with both exposures had a more than eightfold increased likelihood of having ADHD, compared to children with neither exposure. The study estimates that up to 35 percent of ADHD cases in children between the ages of 8 and 15 could be reduced by eliminating exposure to both tobacco and lead.

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The American Academy of Pediatrics is an organization of 60,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well-being of infants, children, adolescents and young adults. For more information, visit www.aap.org.