Bone lead levels and delinquent behavior

Abstract

Objective. —To evaluate the association between body lead burden and social adjustment. Design. —Retrospective cohort study. Setting. —Public school community. Participants. —From a population of 850 boys in the first grade at public schools, 503 were selected on the basis of a risk scale for antisocial behavior. All of the 850 boys who scored in the upper 30th percentile of the distribution on a self-reported antisocial behavior scale were matched with an equal number drawn by lot from the lower 70% of the distribution. From this sample, 301 students accepted the invitation to participate. Exposure Measure. —K x-ray fluorescence spectroscopy of tibia at subjects' age of 12 years. Main Outcome Measures. —Child Behavior Checklist (CBCL), teachers' and parents' reports, and subjects' self-report of antisocial behavior and delinquency at 7 and 11 years of age. Results. —Subjects, teachers, and parents were blind to the bone lead measurements. At 7 years of age, borderline associations between teachers' aggression, delinquency, and externalizing scores and lead levels were observed after adjustment for covariates. At 11 years of age, parents reported a significant lead-related association with the following CBCL cluster scores: somatic complaints and delinquent, aggressive, internalizing, and externalizing behavior. Teachers reported significant associations of lead with somatic complaints, anxious/depressed behavior, social problems, attention problems, and delinquent, aggressive, internalizing, and externalizing behavior. High-lead subjects reported higher scores in subjects' self-reports of delinquency at 11 years. High-lead subjects were more likely to obtain worse scores on all items of the CBCL during the 4-year period of observation. High bone lead levels were associated with an increased risk of exceeding the clinical score (T>70) for attention, aggression, and delinquency. Conclusion. —Lead exposure is associated with increased risk for antisocial and delinquent behavior, and the effect follows a developmental course. (JAMA. 1996;275:363-369)