DEFICITS IN PSYCHOLOGIC AND CLASSROOM PERFORMANCE OF CHILDREN WITH ELEVATED DENTIN LEAD LEVELS

To measure the neuropsychologic effects of unidentified childhood exposure to lead, the performance of 58 children with high and 100 with low dentine lead levels was compared. Children with high lead levels scored significantly less well on the Wechsler Intelligence Scale for Children (Revised) than those with low lead levels. This difference was also apparent on verbal subtests, on three other measures of auditory or speech processing and on a measure of attention. Analysis of variance showed that none of these differences could be explained by any of the 39 other variables studied. Also evaluated by a teachers’ questionnaire was the classroom behavior of all children (2146 in number) whose teeth were analyzed. The frequency of non-adaptive classroom behavior increased in a dose-related fashion to dentine lead level. Lead exposure, at doses below those producing symptoms severe enough to be diagnosed clinically, appears to be associated with neuropsychologic deficits that may interfere with classroom performance. (N Engl J Med 300:689–695, 1979) THE neurotoxic properties of lead at high dose are well known and not a subject of general controversy.1,2 A source of considerable debate, however, is whether or not blood lead levels below those associated with obvious symptoms have adverse effects on the brain.3,4 Because the symptoms of milder lead intoxication are not dramatic, and may therefore evade precise identification, many efforts have been made to determine whether these lesser levels of lead are associated with undetected neuropsychologic impairment.5 6 7 8 9 10 11” Among the reasons for discrepant conclusions in these earlier studies are the following methodologic difficulties shared to some extent by many. © 1979, Massachusetts Medical Society. All rights reserved.