Effect of Environmental Exposure to Lead and Tobacco Smoke on Inattentive and Hyperactive Symptoms and Neurocognitive Performance in Children

Background: The present study assessed the association between blood lead and urinary cotinine levels and inattentive and hyperactive symptoms and neurocognitive performance in children. Methods: A total of 667 children (age range 8-11) were recruited from nine schools in five Korean cities. The teachers and parents completed the Korean version of the Attention-deficit/hyperactivity disorder Rating Scales (K-ARS), and the children performed neurocognitive tests. Blood lead and urinary cotinine levels were then measured. Results: The inattentive, hyperactive, and total scores of the teacher-rated K-ARS were positively associated with blood lead level, and the results of the continuous performance test (CPT), Stroop Color-Word Test, and Children's Color Trails Test were inversely associated with urinary cotinine level when controlled for age, gender, father's educational level, maternal IQ, child's IQ, residential area, birth weight, and cotinine (for lead) or lead (for cotinine). The association between blood lead level and commission errors score on the CPT disappeared when the effect of urinary cotinine level was controlled. Conclusions: These findings indicate that environmental exposure to tobacco smoke in children is associated with poor neurocognitive performance, and low levels of lead are associated with inattention and hyperactivity symptoms.