COGNITION IN CHILDREN DOES NOT SUFFER FROM VERY-LOW LEAD-EXPOSURE

We studied the relationship between exposure to lead and memory and at tention in children. Participants were 313 boys aged 9 to 12 years who attended special education schools in the Netherlands. Children whose possible attentional or memory problems were obviously due to causes other than lead contamination were excluded from the study. Cognition was assessed by extensive theory-based testing. Blood lead concentrati on was measured to assess body lead burden. Possible confounding facto rs that might affect blood lead level and/or cognitive functioning wer e assessed. Blood lead levels were higher in children with lower socio economic status and in children with more hand-to-mouth behavior, and varied seasonally, with higher values in spring and summer. The mean b lood lead level was 44.4 microgram lead per liter blood, which is cons idered low. Only 2% of the children showed a slightly higher blood lea d level than the American safety standard. To obtain robust measures o f cognitive aspects, we performed a factor analysis. The results showe d that blood lead level did not influence any of the cognitive factors . Therefore this study, despite being designed to maximize the chance of finding an effect in asymptomatic children, does not support a rela tionship between lead at very low doses (below 100 micogram/liter bloo d) and cognition in schoolchildren.