Exposure to arsenic has long been known to have neurologic consequences in adults, but to date there are no well-controlled studies in children. We report results of a cross-sectional investigation of intellectual function in 201 children 10 years of age whose parents participate in our ongoing prospective cohort study examining health effects of As exposure in 12,000 residents of Araihazar, Bangladesh. Water As and manganese concentrations of tube wells at each child’s home were obtained by surveying all wells in the study region. Children and mothers came to our field clinic, where children received a medical examination in which weight, height, and head circumference were measured. Children’s intellectual function on tests drawn from the Wechsler Intelligence Scale for Children, version III, was assessed by summing weighted items across domains to create Verbal, Performance, and Full-Scale raw scores. Children provided urine specimens for measuring urinary As and creatinine and were asked to provide blood samples for measuring blood lead and hemoglobin concentrations. Exposure to As from drinking water was associated with reduced intellectual function after adjustment for sociodemographic covariates and water Mn. Water As was associated with reduced intellectual function, in a dose–response manner, such that children with water As levels > 50 μg/L achieved significantly lower Performance and Full-Scale scores than did children with water As levels < 5.5 μg/L. The association was generally stronger for well-water As than for urinary As.

Exposure to manganese via inhalation has long been known to elicit neurotoxicity in adults, but little is known about possible consequences of exposure via drinking water. In this study, we report results of a cross-sectional investigation of intellectual function in 142 10-year-old children in Araihazar, Bangladesh, who had been consuming tube-well water with an average concentration of 793 μg Mn/L and 3 μg arsenic/L. Children and mothers came to our field clinic, where children received a medical examination in which weight, height, and head circumference were measured. Children’s intellectual function was assessed on tests drawn from the Wechsler Intelligence Scale for Children, version III, by summing weighted items across domains to create Verbal, Performance, and Full-Scale raw scores. Children provided urine specimens for measuring urinary As and creatinine and were asked to provide blood samples for measuring blood lead, As, Mn, and hemoglobin concentrations. After adjustment for sociodemographic covariates, water Mn was associated with reduced Full-Scale, Performance, and Verbal raw scores, in a dose–response fashion; the low level of As in water had no effect. In the United States, roughly 6% of domestic household wells have Mn concentrations that exceed 300 μg Mn/L, the current U.S. Environmental Protection Agency lifetime health advisory level. We conclude that in both Bangladesh and the United States, some children are at risk for Mn-induced neurotoxicity.

Millions of persons around the world are exposed to low doses of arsenic through drinking water. However, estimates of health effects associated with low-dose arsenic exposure have been extrapolated from high-dose studies. In Bangladesh, many persons have been exposed to a wide range of doses of arsenic from drinking water over a significant period of time. The authors evaluated dose-response relations between arsenic exposure from drinking water and premalignant skin lesions by using baseline data on 11,746 participants recruited in 2000-2002 for the Health Effects of Arsenic Longitudinal Study in Araihazar, Bangladesh. Several measures of arsenic exposure were estimated for each participant based on well-water arsenic concentration and usage pattern of the wells and on urinary arsenic concentration. In different regression models, consistent dose-response effects were observed for all arsenic exposure measures. Compared with drinking water containing <8.1 microg/liter of arsenic, drinking water containing 8.1-40.0, 40.1-91.0, 91.1-175.0, and 175.1-864.0 microg/liter of arsenic was associated with adjusted prevalence odds ratios of skin lesions of 1.91 (95% confidence interval (CI): 1.26, 2.89), 3.03 (95% CI: 2.05, 4.50), 3.71 (95% CI: 2.53, 5.44), and 5.39 (95% CI: 3.69, 7.86), respectively. The effect seemed to be influenced by gender, age, and body mass index. These findings provide information that should be considered in future research and policy decisions.