Shallow wells are more likely to become contaminated with microorganisms than deep wells. Disinfection is usually needed to prevent diarrheal disease.
Wu, J., A. van Geen, K.M., Ahmed, Y.A. Alam, P.J. Culligan, V. Escamilla, J. Feightery, A.S. Ferguson, P. Knappett, B.J. Mailloux, L.D. McKay, M.L. Serre, P.K. Streatfield, M. Yunus, and M. Emch. Increase in diarrheal disease associated with arsenic mitigation in bangladesh. PLoS One. 2011;6(12):e29593. Epub 2011 Dec 28.
BACKGROUND: Millions of households throughout Bangladesh have been exposed to high levels of arsenic (As) causing various deadly diseases by drinking groundwater from shallow tubewells for the past 30 years. Well testing has been the most effective form of mitigation because it has induced massive switching from tubewells that are high (>50 µg/L) in As to neighboring wells that are low in As. A recent study has shown, however, that shallow low-As wells are more likely to be contaminated with the fecal indicator E. coli than shallow high-As wells, suggesting that well switching might lead to an increase in diarrheal disease.
METHODS: Approximately 60,000 episodes of childhood diarrhea were collected monthly by community health workers between 2000 and 2006 in 142 villages of Matlab, Bangladesh. In this cross-sectional study, associations between childhood diarrhea and As levels in tubewell water were evaluated using logistic regression models.
RESULTS: Adjusting for wealth, population density, and flood control by multivariate logistic regression, the model indicates an 11% (95% confidence intervals (CIs) of 4-19%) increase in the likelihood of diarrhea in children drinking from shallow wells with 10-50 µg/L As compared to shallow wells with >50 µg/L As. The same model indicates a 26% (95%CI: 9-42%) increase in diarrhea for children drinking from shallow wells with ≤10 µg/L As compared to shallow wells with >50 µg/L As.
CONCLUSION: Children drinking water from shallow low As wells had a higher prevalence of diarrhea than children drinking water from high As wells. This suggests that the health benefits of reducing As exposure may to some extent be countered by an increase in childhood diarrhea.
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