During the past grant cycle, working in Araihazar, Bangladesh, where both As and Mn levels in drinking water span a wide range, we have demonstrated that both As and Mn have adverse effects of child intelligence. The current research seeks to further test and elaborate on the hypotheses that As and Mn exposures from drinking water are associated with deficits in intellectual function in two distinct population samples. The first draws on a U.S. sample, for whom we are able to apply standardized scores to estimate the magnitude of association with IQ. The second draws on a Bangladesh sample to examine whether or not the effects of As on intellectual function are reversible; it takes advantage of a Columbia Earth Institute initiative to provide As-free deep tube-well water to an exposed population in Araihazar, Bangladesh.
In New Hampshire (NH), we are conducting a cross-sectional study of 500 fourth-grade children in order to examine the relations between water As, water Mn and IQ. We selected schools to yield a sample in which based on USGS data roughly 70% consume water from wells with < 10 μg As/L, 20% from wells with 10-50 μg/L, and 10% from wells with > 50 μg/L. The distribution of Mn in wells is less well characterized, but limited USGS data indicate that roughly 10% of wells in this region will have Mn concentrations above the EPA Health Advisory Level of 300 µg/L.
In Bangladesh, we are testing the hypothesis that the provision of deep tube-well water (essentially devoid of As and Mn) is associated with improved intellectual function. We are undertaking a two-year prospective study of 300 children (baseline ages 7-9) in a region of Araihazar, Bangladesh. Children will be assessed before remediation and at 12- and 24-months post-remediation. Seventy-five children will be recruited into each of the following four groups: a) low As, low Mn; b) low As, high Mn; c) high As, low Mn; d) high As, high Mn. Based on EPA guidelines, the definition of “low As” will be ≤ 10μg/L, and “low Mn” will be ≤ 300 μg/L. After their initial intellectual assessment, children with high As wells will be provided access to low As (and low Mn) community wells and education to promote their use.
