Objective: The purpose of this study is to explore the association between attention deficit hyperactivity disorder (ADHD) symptoms and exposure to traffic related air pollution (TRAP) in children at risk for atopic disease.
Methods: A cross sectional analysis assessing exposure to TRAP and ADHD symptoms was conducted utilizing seven-year-old children who were participants in a longitudinal birth cohort. They were recruited from a mid-sized metropolitan area with a mix of rural, suburban, and urban areas. Enrollment in the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) cohort required at least one parent with atopy and birth residence either <400m or >1500m from a major highway or bus route. Exposure to TRAP was modeled using data from 27 air monitoring stations over the first year of life using land-use regression modeling. ADHD symptoms were measured using the Hyperactivity, Inattention, Aggression, Conduct Problems, and Atypicality T scores from the Behavioral Assessment System for Children 2nd Edition, Parent Rating Scale (BASC-2).
Results: At age seven, 18.4% of children were reported to have hyperactive behaviors in the “at risk” range (T score > 59), 19.3% had inattentive behaviors, 15.7% had aggressive behaviors, 14.1% had conduct problems, and 14.3% had atypical behaviors. In analysis adjusting for cigarette exposure, maternal education, rhinitis, and habitual snoring, the children with the highest tertile of TRAP exposure during their first year of life had significantly more hyperactive behaviors than children exposed to lower amounts of TRAP (aOR=1.68 [1.02, 2.74]). After stratifying by race, black children who had high TRAP exposure had significantly higher aggressive behaviors than children exposed to lower amounts of TRAP (aOR=4.19 [1.08, 21.58]).
Conclusions: Higher exposure to TRAP is associated with hyperactive behaviors in children at risk for atopy. Black race modifies the association between TRAP exposure and aggressive behaviors.