A cross-sectional study of well water arsenic and child IQ in Maine schoolchildren

Gail A Wasserman,Richard Abramson,Xinhua Liu,Amy Schwartz,Jacob L Mey,Pam Factor-Litvak,Alexander Van Geen,Nancy J Loiacono,Joseph H Graziano,Jennie Kline,Diane Levy

doi:10.1186/1476-069x-13-23

Abstract

BackgroundIn recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors. Because findings are not easily generalizable to the US, we examine this relation in a US population.MethodsIn 272 children in grades 3–5 from three Maine school districts, we examine associations between drinking water As (WAs) and intelligence (WISC-IV).ResultsOn average, children had resided in their current home for 7.3 years (approximately 75% of their lives). In unadjusted analyses, household well WAs is associated with decreased scores on most WISC-IV Indices. With adjustment for maternal IQ and education, HOME environment, school district and number of siblings, WAs remains significantly negatively associated with Full Scale IQ and Perceptual Reasoning, Working Memory and Verbal Comprehension scores. Compared to those with WAs < 5 μg/L, exposure to WAs ≥ 5 μg/L was associated with reductions of approximately 5–6 points in both Full Scale IQ (p < 0.01) and most Index scores (Perceptual Reasoning, Working Memory, Verbal Comprehension, all p’s < 0.05). Both maternal IQ and education were associated with lower levels of WAs, possibly reflecting behaviors (e.g., water filters, residential choice) limiting exposure. Both WAs and maternal measures were associated with school district.ConclusionsThe magnitude of the association between WAs and child IQ raises the possibility that levels of WAs ≥ 5 μg/L, levels that are not uncommon in the United States, pose a threat to child development.

Highlights

In recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors
In our initial work with 6- [1] and 10-year olds [2], after adjustment for social factors related to intellectual function, water arsenic concentration (WAs) was significantly negatively related to WPPSI-III and WISC-III Performance scores, but, in most instances, not to other components of intelligence, such as Verbal scores
WAs and both Verbal Comprehension and Working Memory scores from the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) remained marginally significant after adjustment for socio-demographic features and for co-occurring exposure to manganese in drinking water; WAs was unrelated to other aspects of intellectual functioning

Summary

Introduction

In recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors. In our initial work with 6- [1] and 10-year olds [2], after adjustment for social factors related to intellectual function, water arsenic concentration (WAs) was significantly negatively related to WPPSI-III and WISC-III Performance (nonverbal ability) scores, but, in most instances, not to other components of intelligence, such as Verbal scores. WAs and both Verbal Comprehension and Working Memory scores from the WISC-IV remained marginally significant after adjustment for socio-demographic features and for co-occurring exposure to manganese in drinking water; WAs was unrelated to other aspects of intellectual functioning. While several studies in different populations suggest that As exposure may affect early development, there is little consistency in the specific components of child intelligence most affected

Methods

Results

Discussion

Conclusion