Neuropsychological effects of chronic asymptomatic increased lead absorption. A controlled study.

Twenty-seven asymptomatic children with confirmed chronic increased lead absorption were compared with 27 matched control children for evidence of neuropsychological impairment. Evaluation of each child included a complete history, physical examination, quantitative neurological tests, and comprehensive psychological tests. There was significantly increased incidence of hyperactive behavior in the subjects with increased lead levels, but there was no significant difference in any of the quantitative test results. Uncontrolled variables, especially lead absorption in infancy and adverse environmental pressures other than lead, still leave questions about the relationship between chronic lead exposure and behavior of intelligence.