Pediatric health researchers analyzed data from the 1999-2002 National Health and Nutrition Examination Survey (NHANES) to determine any relationships between attention deficit hyperactivity disorder (ADHD) in children, ages 4 to 15 years, and children’s exposure to tobacco smoke and to environmental lead (“neurotoxicants”). 

NHANES involves a large nationally representative sample of children with oversampling of young (<5 years), Mexican-American and non-Hispanic Black children.  For this study, exposure to prenatal (at any time during the pregnancy) and postnatal household tobacco was based on the parent’s report.  Lead levels were determined by participating children’s blood tests. Having ADHD was defined as the parent’s report of ADHD being diagnosed by a doctor or health professional and use of a stimulant medication.

In this sample, 458 children who reportedly lacked a source of regular medical care were excluded because they were unlikely to be on any medication.  Of the 4704 remaining cases, 4.2% met the definition of ADHD for this study.  (8.2% were reported to have a diagnosis of ADHD but not all were reported to be on a stimulant medication.)

Parent-reported ADHD was associated with prenatal tobacco exposure, preschool attendance, male gender, being a non-Hispanic White, older age, and having health insurance.  Multi-variable data analysis suggested that prenatal tobacco exposure accounted for 18.4% of cases of ADHD.  Postnatal tobacco exposure was not associated with ADHD. Children with blood lead levels in the 5th quintile (2.0-5.0µg/dL) were at a significantly higher risk for ADHD than children in the lowest quintile (<0.70µg/dL). Environmental lead exposure (>2.0 µg/dL) accounted for 21.1% of cases of ADHD.

(Braun J et al. Environ Health Perspect 2006; doi:10.1289/ehp.9478. [Online 19 September 2006] available http://ehp.niehs.nih.gov/docs/2006/9478/abstract.html) --J.O.