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.

Poor stimulation in the home is one of the main factors affecting the development of children living in poverty. The family care indicators (FCIs) were developed to measure home stimulation in large populations and were derived from the Home Observations for Measurement of the Environment (HOME). The FCIs were piloted with 801 rural Bangladeshi mothers of children aged 18 months. Five subscales were created: 'play activities' (PA), 'varieties of play materials' (VP), 'sources of play materials', 'household books', and 'magazines and newspapers' (MN). All subscales had acceptable short-term reliability. Mental and motor development of the children was assessed on the Bayley Scales of Infant Development and their language expression and comprehension by mothers' report. After controlling for socioeconomic variables, VP and PA independently predicted four and three of the developmental outcomes respectively, and MN predicted both the Bayley scores. The FCI is promising as a survey-based indicator of the quality of children's home environment. Key words: Care-giving behaviours; Child development; Cognitive development; Family care indicators; Home environment; Bangladesh DOI: 10.3329/jhpn.v28i1.4520 J Health Popul Nutr 2010 Feb; 28(1): 23-33

A peer-reviewed open access journal published by the National Institute of Environmental Health Sciences

Early-Life Cadmium Exposure and Child Development in 5-Year-Old Girls and Boys: A Cohort Study in Rural Bangladesh

Background: Iron and zinc deficiency are prevalent during infancy in low-income countries. Objectives: The objectives were to examine whether a weekly supplement of iron, zinc, iron+zinc, or a micronutrient mix (MM) of 16 vitamins and minerals would alter infant development and behavior. Design: The participants were 221 infants from rural Bangladesh at risk of micronutrient deficiencies. Development and behavior were evaluated at 6 and 12 mo of age by using the Bayley Scales of Infant Development II and the Home Observation Measurement of Environment (HOME) scale. In this double-blind trial, the infants were randomly assigned to 1 of 5 treatment conditions: iron (20 mg), zinc (20 mg), iron+zinc, MM (16 vitamins and minerals, including iron and zinc), or riboflavin weekly from 6 to 12 mo. Multivariate analyses were conducted to examine the change in development and behavior for each supplementation group, with control for maternal education, HOME score, months breastfed, anemia, growth at 6 mo, and change in growth from 6 to 12 mo. Results: Iron and zinc administered together and with other micronutrients had a beneficial effect on infant motor development. Iron and zinc administered individually and in combination had a beneficial effect on orientation-engagement. Two-thirds of the infants were mildly anemic, no treatment effects on hemoglobin concentration were observed, and hemoglobin was not associated with measures of development or behavior. Conclusion: The beneficial effects of weekly iron and zinc supplementation on motor development and orientation-engagement suggest that infants benefit from these minerals when administered together.