Early-life exposure to ambient benzene, toluene, ethylbenzene and xylene and ADHD-related behaviors and diagnosis among a nationally-representative sample of kindergarten children.

Abstract

Introduction: Benzene, toluene, ethyl benzene and xylene (BTEX) are a group of volatile organic compounds previously linked to adverse birth outcomes and cognitive development. This study aimed to determine if early-life exposure to BTEX in the ambient air was associated with behaviors suggestive of attention-deficit and hyperactivity disorder (ADHD). Methods: Using residential ZIP Code at 9 months of age, annual average estimates of BTEX compounds from the 2002 U.S. EPA’s National Air Toxics Assessment were linked to parent and teacher interviews for 4,900 children who participated in the Early Child Longitudinal Study, Birth Cohort (ECLS-B). The ECLS-B is a nationally-representative sample of U.S. children born in 2001 and followed from 9 months of age through kindergarten. Kindergarten teachers rated children on six behaviors related to ADHD symptomology using a 5-point likert scale. After summing across the six behavior scales, children with summary scores in the bottom decile were classified as displaying behaviors suggestive of ADHD symptomology. Multivariable logistic regression models, accounting for the complex study design and adjusted for maternal race, age, marital status, household language, socioeconomic status, a neighborhood deprivation index, and home environment were constructed. Results: Children exposed to the upper quartile of benzene had 1.45 times the odds of displaying behaviors suggestive of ADHD-related symptomology than children with lower levels of exposure (95% confidence interval, CI, 1.11, 1.89). No associations were observed with other BTEX compounds or with parent-reported behaviors. Only 2.4% of children had a parent-reported diagnosis of ADHD, but children exposed to the highest quartile for all BTEX compounds had 1.88 times the odds of having an ADHD diagnosis than other children (95% CI 1.03, 3.42). Conclusions: These findings add to a growing literature that air pollution may impact children’s neurobehavioral development.