Relationship of blood lead levels with visual-motor and equilibrium disturbances in children aged 8 to 10 years.

Objective. To assess the association between blood lead concentrations and visual-motor coordination and equilibrium in school age children. Material and methods. In November-December 1998, a cross-sectional study was conduct ed among 255 children aged 8-10, who attended public schools in Sector I of the Oaxaca State Public Education Institute. Data were collected using the Frostig Evaluation of Visual Perception test and the equilibrium subscale of the Frostig Movement Skills Test Battery. A blood sample was taken to me asure lead levels by atomic absorption spectrometry. Socioeconomic data and health histories were collected for use as control variables. Statistical analysis consisted of multiple regression models to test the relationship b etween blood lead level and the visual-motor and equilibrium tests. We asse ssed the efect of lead within the model using 1 000 Montecarlo simulations. Results. The geometric mean of blood lead concentrations was 11.5 mu g/dl (geometric standard deviation +6.3, -5.2). After adjusting for control vari ables, the visual-motor integration subscale was significantly related to b lood lead concentration (p> 0.042). The visual-motor integration value decr eased 1.78 (95% CI -3.51,-0.06) points for each 10 mu g/dl increase in bloo d lead concentration. Among the four sub-tests comprising the visual-motor integration subscale, only eye-hand coordination (p=0.045) and spatial rela tions (p=0.039) were significantly related to blood lead. The visual-motor integration subscale was also significantly related to family income;greate r income was related to greater testing scores. Only 3.1% of the children h ad clinically abnormal testing scores. No statistically significant associa tion was found between blood lead levels and the Frostig subscale Index of Reduced Motor Response, the General Visual Perception Index, or any other e quilibrium tests. Conclusions. The inverse relationship between blood lead concentration and visual-motor skill is consistent with results from studie s in other countries. Blood lead levels common among children of Oaxaca are sufficient to produce subtle visual-motor impairments. These findings poin t out the need to strengthen the initiative to reduce child exposure to kno wn lead sources,particularly lead-glazed ceramics, and thus lower the blood lead levels of the population.