Arsenic Exposure and Cognitive Performance in Mexican School children

BACKGROUND: Previous studies have suggested an effect of high arsenic concentration on cognitive and neurobehavioral function in humans. OBJECTIVE: Out goal was to identify demographic and nutritional factors that are associated with As exposure and the influence of this exposure on cognitive function in school-age children. Methods: We recruited 602 children 6-8 years of age living within 3.5 km of a metallurgic smelter complex in the city of Torreon, Mexico, to participate in a cross-sectional evaluation. Of these, 591 had complete anthropometry, iron, and zinc status by biochemical measurements in serum, blood lead concentration (PbB), and arsenic in urine (UAs), and 557 completed several cognitive performance tests. RESULTS: The mean for UAs was 58.1 plus or minus 33.2 mu g/L; 52% of the children had UAs concentrations > 50 mu g/L, and 50.7% of children had PbB greater than or equal to 10 mu g/dL. UAs concentration was associated with low socioeconomic status. Nutritional status indicators were not related to UAs concentrations. Linear and logistic regressions adjusted for hemoglobin concentration, PbB, and sociodemographic con-founders showed a significant inverse association between UAs and Visual-Spatial Abilities with Figure Design, the Peabody Picture Vocabulary Test, the WISC-RM Digit Span subscale, Visual Search, and Letter Sequencing Tests (p < 0.05). Boys excreted significantly more UAs (p < 0.05) and were affected on different cognitive areas than girls. CONCLUSIONS: Children living in an area contaminated with both As and lead showed that As contamination can affect children's cognitive development, independent of any effect of lead.