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Salud Pública de México

Print version ISSN 0036-3634


AZCONA-CRUZ, María Isabel et al. Relationship of blood lead levels with visual-motor and equilibrium disturbances in children aged 8 to 10 years. Salud pública Méx [online]. 2000, vol.42, n.4, pp.279-287. ISSN 0036-3634.

OBJECTIVE: To assess the association betwen 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 conducted among 255 children aged 8-10, who attended public schools in Sector 1 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 measure 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 between blood lead level and the visual-motor and equilibrium tests. We assessed the efect of lead within the model using 1 000 Montecarlo simulations. RESULTS: The geometric mean of blood lead concentrations was 11.5 µg/dl (geometric standard deviation +6.3, -5.2). After adjusting for control variables, the visual-motor integration subscale was significantly related to blood lead concentration (p> 0.042). The visual-motor integration value decreased 1.78 (95% CI -3.51, -0.06) points for each 10 µg/dl increase in blood lead concentration. Among the four sub-tests comprising the visual-motor integration subscale, only eye-hand coordination (p=0.045) and spatial relations (p=0.039) were significantly related to blood lead. The visual-motor integration subscale was also significantly related to family income; greater income was related to greater testing scores. Only 3.1% of the children had clinically abnormal testing scores. No statistically significant association was found between blood lead levels and the Frostig subscale Index of Reduced Motor Response, the General Visual Perception Index, or any other equilibrium tests. CONCLUSIONS: The inverse relationship between blood lead concentration and visual-motor skill is consistent with results from studies in other countries. Blood lead levels common among children of Oaxaca are sufficient to produce subtle visual-motor impairments. These findings point out the need to strengthen the initiative to reduce child exposure to known lead sources, particularly lead-glazed ceramics, and thus lower the blood lead levels of the population.

Keywords : lead [blood]; psychomotor performance; equilibrium; child; Mexico.

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