Children??s Intellectual Function in Relation to Arsenic Exposure

Abstract

Current arsenic concentrations in urine, which reflect all sources of recent exposure, including water and food, were associated with small decrements in intellectual testing in school-aged children in West Bengal. We did not see associations between long-term water arsenic concentrations and intellectual function.

Inorganic Arsenic Exposure and Children’s Neurodevelopment: A Review of the Evidence

“…In the few studies that collected data on arsenic exposures during different periods of a child's life, it appears that biomarkers of recent exposure might be somewhat more strongly associated with neurodevelopmental test scores than are biomarkers of prenatal exposure. In a study conducted in West Bengal (India) [34], test scores at ages 5-15 years were inversely associated with children's urinary arsenic concentrations but not with peak arsenic concentration in the water consumed by the mother during pregnancy, or with cumulative water arsenic exposure in the interval since birth. In a prospective study in Bangladesh [37][38][39], IQ score at age 5 years was inversely associated with mothers' urinary arsenic concentrations at weeks 8 and 30 of gestation and with children's urinary arsenic at 18 months, but the associations were strongest for children's urinary arsenic at the time of testing.…”

“…In a meta-analysis of four ecologic Chinese studies, the weighted mean deficit in the IQ scores of children living in the "arsenicosis" towns, compared to the children living in the "non-arsenicosis" towns, was 6.85 points [48]. In the Bengali study of von Ehrenstein et al [34], children in the upper tertile of urinary arsenic (>83 µg /L) had reductions of 12%-24% in their scores on selected IQ subtests. In two studies conducted in Bangladesh, water arsenic level accounted for approximately 4% of the variance in the IQ scores of 10 year olds [31] and approximately 1% of the variance in the IQ scores of 6 year olds [33].…”

“…One of the more consistent findings is that increased arsenic exposure is associated with decrements in language-based skills, including Verbal IQ [29,32,39,40], verbal learning [32], digit span (memory for number strings) [36], story memory [32], and vocabulary [34]. On the other hand, inverse associations have also been reported for a variety of nonverbal endpoints, including Performance IQ and Processing Speed [33,31], individual subtests of the Wechsler scales that contribute to Performance IQ, such as Object Assembly (simple jigsaw puzzles) and Picture Completion (attention to visual detail) [34], visual-spatial abilities and sequencing [36], and motor skills such as body coordination and fine manual control [49].…”

“…On the other hand, inverse associations have also been reported for a variety of nonverbal endpoints, including Performance IQ and Processing Speed [33,31], individual subtests of the Wechsler scales that contribute to Performance IQ, such as Object Assembly (simple jigsaw puzzles) and Picture Completion (attention to visual detail) [34], visual-spatial abilities and sequencing [36], and motor skills such as body coordination and fine manual control [49].…”

“…Among studies that measured individual exposures, some relied on biomarkers such as blood, urinary, and hair arsenic, while other studies measured only external exposures such as water arsenic concentrations at different time points (e.g., concurrent, peak, gestational, lifetime). In studies in which both external and internal exposures were measured, the correlations between current water arsenic and urinary arsenic concentration were often modest, e.g., 0.12 [34], 0.31 [33], and 0.45 [31], suggesting that the information they provide about exposure is complementary rather than redundant. Higher correlations tend to be found between different arsenic biomarkers (e.g., pregnancy urinary and blood arsenic) [44].…”