Association between lower level lead concentrations and hyperactivity in children.

Hyperactive children were compared with a nonhyperactive control group on two measures that reflect the presence of body lead and on a lead exposure questionnaire. The overall hypothesis that was tested was that a relationship exists between hyperactivity in children and a concommitant condition of increased body lead stores. Operationally, the hypothesis was reduced to a comparison of the hyperactive group and control group on the following measures: (1) blood lead levels; (2) post-penicillamine urine lead levels; (3) scores on a lead exposure questionnaire. The designation hyperactive or nonhyperactive was arrived at by using three different measurements: a doctor's diagnosis; a teacher's rating scale; a parent questionnaire. Hyperactive children had significantly higher values on all three measures than did the controls. More than half the hyperactive children had blood lead levels in the range considered to be raised but not toxic, and 60% of post-penicillamine urine levels were in the "toxic" range. It is concluded that there is an association between hyperactivity and raised lead levels, that a large body-lead burden may exact consequencies that have hitherto been unrealized; that the definition of what is a toxic level for blood lead needs reevaluation and that physicians should look for raised lead levels in children with hyperactivity.