In a study published in the December issue of Pediatrics researchers from the department of pediatrics at Cincinnati Children's Hospital Medical Center, analysed data of prenatal tobacco and childhood lead exposure in 2,588 youngsters from eight to 15 from the National Health and Nutrition Examination Survey 2001-2004, 8.7% of whom met criteria for diagnosis with ADHD.
Prenatal tobacco exposure was measured by reports of cigarette use during pregnancy, and childhood lead exposure was assessed by blood levels.
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 diagnosis.
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.
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First published in November 2009
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