Elevated childhood exposure to arsenic despite reduced drinking water concentrations — A longitudinal cohort study in rural Bangladesh

OBJECTIVES: The aim of this study was to evaluate the massive efforts to lower water arsenic concentrations in Bangladesh. METHODS: In our large mother-child cohort in rural Matlab, we measured the arsenic concentrations (and other elements) in drinking water and evaluated the actual exposure (urinary arsenic), from early gestation to 10 years of age (n=1017). RESULTS: Median drinking water arsenic decreased from 23 (2002-2003) to <2 μg/L (2013), and the fraction of wells exceeding the national standard (50 μg/L) decreased from 58 to 27%. Still, some children had higher water arsenic at 10 years than earlier. Installation of deeper wells (>50 m) explained much of the lower water arsenic concentrations, but increased the manganese concentrations. The highest manganese concentrations (~900 μg/L) appeared in 50-100 m wells. Low arsenic and manganese concentrations (17% of the children) occurred mainly in >100 m wells. The decrease in urinary arsenic concentrations over time was less apparent, from 82 to 58 μg/L, indicating remaining sources of exposure, probably through food (mean 133 μg/kg in rice). CONCLUSION: Despite decreased water arsenic concentrations in rural Bangladesh, the children still have elevated exposure, largely from food. Considering the known risks of severe health effects in children, additional mitigation strategies are needed.