Lead at low dose and the behavior of children.

Over 3,000 children attending first and second grade in public school were classified as to past lead exposure according to the concentrations of lead in their teeth. Those in the highest and lowest deciles for lead were evaluated by a broad panel of neuropsychologic outcome measures. Controlled either by matching or analysis of covariance were 39 other variables which could effect outcome. High lead children were significantly impaired on IQ auditory processing and reaction time under varying intervals of delay. Teacher's rating scales showed a dose-related increase in non-adaptive classroom behavior with no evidence of a threshold. EEG scores and observations of children in class demonstrated differences in high and low lead subjects.