EXPOSURE TO ENVIRONMENTAL LEAD AND VISUAL-MOTOR INTEGRATION AT AGE 7 YEARS - THE PORT-PIRIE COHORT STUDY

Early childhood exposure to environmental lead may result in subtle de ficits in neuropsychological development. Most studies, however, have reported global measures of development, and the findings have not bee n consistent. In this report, we examine the association between blood lead concentration and a specific aspect of neuropsychological develo pment, visual-motor integration. Each child in a cohort of 494 childre n living in and around the lead smelting town of Port Pirie, South Aus tralia, was followed for its first 7 years of life. Serial blood sampl es were collected at various ages to estimate the lifetime burden of e ach individual. At the time of each blood sampling, systematic informa tion was obtained on a wide range of other variables relevant to child development. We evaluated visual motor integration at age 7 with the Beery Developmental Test of Visual-Motor Integration (mean score: 13.4 ). There was an inverse relation between blood lead concentration and visual-motor performance. After adjustment for potential confounding f actors, both prenatal and postnatal blood lead concentrations exhibite d a dose-related inverse association with children's visual-motor perf ormance. For an increase in life-time average blood lead concentration from 10 mu g per dl (0.48 mu mol per liter) to 30 mu g per dl (1.45 m u mol per liter), the estimated deficit in children's visual-motor per formance was 1.6 points (95% confidence interval = 0.3-2.9). The resul ts indicate that visual-motor integration may be a more sensitive inde x than global measures of development, such as intelligence quotient, for the assessment of lead effects on child development.