Critical windows of exposure for arsenic-associated impairment of cognitive function in pre-school girls and boys: a population-based cohort study

• Published in: International journal of epidemiology Vol. 40; no. 6; pp. 1593 - 1604
• Main Authors: Hamadani, JD, Tofail, F, Nermell, B, Gardner, R, Shiraji, S, Bottai, M, Arifeen, SE, Huda, SN, Vahter, M
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.12.2011
• Subjects: Age; Analysis; Arsenic; Arsenic - toxicity; Arsenic - urine; Arsenic Poisoning - complications; Arsenic Poisoning - epidemiology; Arsenic Poisoning - urine; Bangladesh - epidemiology; Biological and medical sciences; Body Weights and Measures; Boys; Child Development - drug effects; Child Nutrition Disorders - complications; Child Nutrition Disorders - epidemiology; Child, Preschool; Children; Cognition Disorders - chemically induced; Cognition Disorders - urine; Cognitive ability; Drinking water; Environmental Exposure - adverse effects; Environmental Exposure - analysis; Environmental Exposure - statistics & numerical data; Epidemiology; Female; General aspects; Gestation; Girls; Health Surveys; Humans; Infant; Intelligence; Intelligence - drug effects; Intelligence Tests; Longitudinal Studies; Male; Medical sciences; Medicin och hälsovetenskap; Miscellaneous; Pregnancy; Prenatal Exposure Delayed Effects - chemically induced; Prenatal Exposure Delayed Effects - epidemiology; Prenatal Exposure Delayed Effects - urine; Public health. Hygiene; Public health. Hygiene-occupational medicine; Regression analysis; Rural areas; Sex Factors; Side effects; Socioeconomic Factors; Urine; Water; Water Pollutants, Chemical - toxicity; Water Pollutants, Chemical - urine; Water Supply; Bangladesh; Pregnancy; cognitive function; arsenic exposure; maternal urinary arsenic; child urinary arsenic; intelligence quotient; gender differences; Human; Preschool age; Arsenic; Sex; Male; Cognition; Exposure; Epidemiology; Statistical study; Mother; Cohort study; Female; Population; Woman; Child; Public health; Intelligence quotient
• ISSN: 0300-5771; 1464-3685; 1464-3685
• DOI: 10.1093/ije/dyr176

Background Exposure to arsenic through drinking water has been associated with impaired cognitive function in school-aged children in a few cross-sectional studies; however, there is little information on critical windows of exposure. Methods We conducted a population-based longitudinal study in rural Bangladesh. We assessed the association of arsenic exposure, based on urinary arsenic (U-As; twice during pregnancy and twice in childhood), with the development of about 1700 children at 5 years of age using Wechsler Pre-school and Primary Scale of Intelligence [intelligence quotient (IQ)]. Results Median maternal U-As in pregnancy was 80 µg/l (10-90 percentiles: 25-400 µg/l). Children's urine contained 35 (12-155) µg/l and 51 (20-238) µg/l at 1.5 and 5 years, respectively. Using multivariable-adjusted regression analyses, controlling for all potential confounders and loss to follow-up, we found that verbal IQ (VIQ) and full scale IQ (FSIQ) were negatively associated with (log) U-As in girls. The associations were consistent, but somewhat stronger with concurrent arsenic exposure [VIQ: B = −2.4, 95% confidence interval (CI) = −3.8 to −1.1; FSIQ: B = −1.4, 95% CI = −2.7 to −0.1, n = 817), compared with that at 1.5 years (VIQ: B = −0.85, 95% CI = −2.1 to 0.4; FSIQ: B = −0.74, 95% CI = −1.9 to 0.4, n = 902), late gestation (VIQ: B = −1.52, 95% CI = −2.6 to −0.4; FSIQ: B = −1.35, 95% CI = −2.4 to −0.3, n = 874) and early gestation (VIQ: B = −1.23, 95% CI = −2.4 to −0.06; FSIQ: B = −0.92, 95% CI = −2.0 to −0.2, n = 833). In boys, U-As showed consistently low and non-significant associations with all IQ measures. An effect size calculation indicated that 100 µg/l U-As was associated with a decrement of 1-3 points in both VIQ and FSIQ in girls. Conclusion We found adverse effects of arsenic exposure on IQ in girls, but not boys, at 5 years of age.