Exposures to Environmental Toxicants and Attention Deficit Hyperactivity Disorder in US Children

Abstract +
Objective: The purpose of this study was to examine the association of exposures to tobacco smoke and environmental lead with attention deficit hyperactivity disorder (ADHD).

Methods: Data was obtained from the National Health and Nutrition Examination Survey 1999- 2002. Prenatal and postnatal tobacco exposure was based on parent report; lead exposure was measured using blood lead concentration. ADHD was defined as current stimulant medication use and parent report of ADHD diagnosed by a doctor or health professional.

Results: Of 4,704 children age 4 to 15 years, 4.2% were reported to have ADHD and stimulant medication use, equivalent to 1.8 million children in the U.S. In multivariable analysis, prenatal tobacco exposure (Odds Ratio [OR]: 2.5; 95% CI: 1.2, 5.2) and higher blood lead concentration (first vs. fifth quintile, OR: 4.1; 95% CI: 1.2, 14.0) were significantly associated with ADHD.

Postnatal tobacco smoke exposure was not associated with ADHD (OR 0.6; 95% CI: 0.3, 1.3; p=0.22). If causally linked, these data 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.

This study confirms the previously observed association of prenatal tobacco smoke exposure and ADHD. We also found a significant dose-response relationship between childhood lead exposure and ADHD. This analysis indicates that 270,000 ADHD cases in children age 4 to 15 years are attributable to prenatal tobacco smoke exposure and 290,000 cases of ADHD among U.S. children age 4 to 15 years are attributable to environmental lead exposure. The findings of this study underscore the profound behavioral health impact of these prevalent exposures, and highlight the need to strengthen public health efforts to reduce prenatal tobacco smoke exposure and childhood lead exposure.

Conclusions: We conclude that exposure to prenatal tobacco and environmental lead are risk factors for ADHD in U.S. children.

http://www.ehponline.org/members/2006/9478/9478.pdf