Abstract
BackgroundThe people of Bangladesh are currently exposed to high concentrations of arsenic and manganese in drinking water, as well as elevated lead in many regions. The objective of this study was to investigate associations between environmental exposure to these contaminants and neurodevelopmental outcomes among Bangladeshi children.MethodsWe evaluated data from 524 children, members of an ongoing prospective birth cohort established to study the effects of prenatal and early childhood arsenic exposure in the Sirajdikhan and Pabna Districts of Bangladesh. Water was collected from the family’s primary drinking source during the first trimester of pregnancy and at ages 1, 12 and 20–40 months. At age 20–40 months, blood lead was measured and neurodevelopmental outcomes were assessed using a translated, culturally-adapted version of the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III).ResultsMedian blood lead concentrations were higher in Sirajdikhan than Pabna (7.6 vs. <LODμg/dL, p <0.0001) and water arsenic concentrations were lower (1.5 vs 25.7 μg/L, p <0.0001). Increased blood lead was associated with decreased cognitive scores in Sirajdikhan (β = −0.17, SE = 0.09, p = 0.05), whereas increased water arsenic was associated with decreased cognitive scores in Pabna (β = −0.06, SE = 0.03, p = 0.05). Water manganese was associated with fine motor scores in an inverse-U relationship in Pabna.ConclusionWhere blood lead levels are high, lead is associated with decreased cognitive scores on the BSID-III, and effects of other metals are not detected. In the setting of lower lead levels, the adverse effects of arsenic and manganese on neurodevelopment are observed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12940-016-0127-y) contains supplementary material, which is available to authorized users.
Highlights
The people of Bangladesh are currently exposed to high concentrations of arsenic and manganese in drinking water, as well as elevated lead in many regions
More children from Sirajdikhan were excluded compared to Pabna (41.5 vs. 29.0 %, p = 0.0001) because the LeadCare II machine was temporarily not working at that site, and there were differences in maternal Raven score (p
Children who were excluded from analyses had mothers who had less formal education, lower maternal Raven scores, and they had slightly higher HOME scores and gestational age, the difference in gestational age was not clinically significant
Summary
The people of Bangladesh are currently exposed to high concentrations of arsenic and manganese in drinking water, as well as elevated lead in many regions. The objective of this study was to investigate associations between environmental exposure to these contaminants and neurodevelopmental outcomes among Bangladeshi children. Rodrigues et al Environmental Health (2016)5:4 high As and Mn concentrations are not necessarily correlated [6]. Exposure to lead (Pb) presents a third health threat prevalent in Bangladesh. While there are no published nationwide surveys on Pb exposures in Bangladesh, several studies have reported blood Pb levels >10 μg/dL, indicating high exposures among children [7,8,9]. It has been shown that concurrent drinking water As concentrations were negatively associated with cognitive function among children in Bangladesh [11, 12]. Claus Henn et al found a nonlinear relationship between blood Mn concentrations at 12 months of age and 12-month mental development index with the inflexion point around 2.4 μg/dL [20] and others have found a similar non-linear relationship between hair and blood Mn and IQ [21]
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