Neuropsychological studies in children with elevated tooth-lead concentrations. I. Pilot study

In contrast to blood-lead (PbB), tooth-lead concentrations (PbT) provide retrospective information about longterm, cumulative childhood lead-intake. From a basic sample of 458 school age children from the city of Duisburg (FRG), whose lead-concentrations in shed incisor teeth had been measured (means = 4.6 ppm; range: 1.4-12.7 ppm), two extreme-groups of 26 children each (mean age: 8.5 years) with low (means = 2.4 ppm) and elevated (means = 9.2 ppm) PbT were selected. After pair-matching both groups for age, sex, and father's occupational status, these children were tested under double-blind precautions for intellectual performance (German WISC), for perceptual-motor integration (Göttinger Formreproduktionstest = GFT, Diagnostikum für Cerebralschädigung = DCS, Benton-Test), and for gross motor-coordination (Körper-Koordinationstest für Kinder = KTK). Significant (P less than 0.05) inferiority of the lead-children was found in two tests of perceptual-motor integration (increased GFT-errors; lower success rate for DCS). In addition a near significant (P less than 0.1) reduction of 5-7 IQ-points was determined in these children. Although this pilot study has provided some evidence for an association between childhood lead-exposure and neuropsychological impairment, this association cannot yet be considered proven, because the observed effects were discrete and statistically confirmed only in part, and because there was a slight prevalence of perinatal risk factors in the lead group. Further research to clarify the issue is necessary.