Presentation on theme: "Jennifer Winston, Veronica Escamilla, Carolina Perez-Heydrich, Margaret Carrel, Mohammad Yunus, Peter Kim Streatfield, Michael Emch."— Presentation transcript:
Jennifer Winston, Veronica Escamilla, Carolina Perez-Heydrich, Margaret Carrel, Mohammad Yunus, Peter Kim Streatfield, Michael Emch
Introduction This study investigates whether deep tubewells installed for arsenic mitigation in rural Bangladesh also protect children from diarrheal diseases.
Background 1970s and 1980s: government and NGO community installed millions of shallow tubewells (<140 ft) throughout Bangladesh. Led to nearly universal shift from drinking surface water to groundwater. Coupled with improved hygiene and sanitation, tubewell use may have contributed to overall decline in diarrhea induced deaths observed in Bangladesh.
Background In 1990s, naturally occurring arsenic found in shallow tubewells, at levels exceeding the WHO and Government of Bangladesh drinking water standards. About half of the country’s population was exposed to levels exceeding the WHO standard. By 2000, the Bulletin of the WHO had declared a "public health emergency." Prolonged exposure can lead to health problems ranging from skin problems to cancer. Photo: SOS arsenic
Background Nearly 5 million wells were tested for arsenic. Tubewells exceeding the Bangladesh arsenic standard were painted red. Safe wells were painted green. Since 2000, an estimated 165,000 deep tubewells have been installed (usually more than 500 feet deep). Usually public, due to high installation costs. Often located near a rural road or walking path where villagers will have easy access. Photo: Yubanet.com
Background Mitigation responses by Bangladeshis: 1. switch from a shallow high arsenic well to the nearest shallow low arsenic well. May expose users to higher levels of fecal contamination(?) 2. obtain drinking water from a deep tubewell tapping into an aquifer usually more than 500 feet deep.
Study setting and data Matlab, a rural region in Bangladesh, where households clustered in baris (5,279 in this study). Field site for the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b). Community level childhood diarrheal disease survey (2005-2006) Health and demographic surveillance system (since 1966), maintains records of all residents. In 2005, collected SES data.
Study setting and data Survey of Matlab’s 12,018 tubewells (2002-2004). Locations recorded using global positioning system receivers. Information on tubewell depth gathered from well owners, who generally know the length of PVC pipe used to install the well. Supplemented by a 2009 survey asking people to identify any deep community tubewell in or adjacent to their bari. Photo: icddr,b
Methods Made assumptions about deep and shallow tubewell use: Measured distance from each bari to the nearest deep tubewell in GIS. Defined deep and shallow tubewell use according to the following assumptions:
Methods Tested the accuracy of assumptions about tubewell use by building a logistic regression model to predict surveyed deep tubewell use in a six village sub-sample. Deep tubewell use was correctly classified for 76% of the time. Longitudinal logistic regression model Outcome of interest: binary variable of occurrence of childhood diarrhea within the year. Main predictor of interest: binary variable for deep tubewell use. Covariates: Wealth index, maternal education, population of children under 5, and year.
Results Overall, the distribution of counts of childhood diarrhea was found to be wider and more variable for shallow tubewell users than for deep tubewell users.
Results, continued ParameterOR95% CI Deep tubewell use0.5130.365 – 0.722 Population < 5 yrs1.0951.076 – 1.111 Maternal education0.9650.931 – 1.000 Wealth Index0.9630.876 – 1.059 Distance to nearest deep tubewell1.0000.999 – 1.000 Year0.8170.753 – 0.886 Distance: Use1.0020.998 – 1.006
Limitations Assumption regarding deep tubewell use. Correctly classified 76% of baris in sub-sample with known tubewell use Sensitivity analysis: 1. Randomly selected 25% of sample baris and re-classified deep tubewell use. 2. Re-ran analysis using reclassified use variable. 3. Results were consistent with those obtained using the original data. Protective effect of deep tube well use was lower (OR: 0.789, 95% CI: 0.642 - 0.971), though still significantly below 1.0.
Conclusions Deep tubewells seem to have a protective effect against childhood diarrhea incidence. At least within 150 meters, distance does not seem to have an effect on childhood diarrheal disease incidence amongst users of deep tubewells. Further development of the deep tubewell infrastructure in rural Bangladesh requires several considerations: Deep tubewells are expensive, so government and NGO’s need to be involved. Community training on deep tubewell maintenance is also needed to avoid unsafe practices. The sustainability of deep groundwater quality must also be considered.
Acknowledgements International Centre for Diarrheal Disease Research, Bangladesh (ICDDR,B) and its core donors: the Australian International Development Agency, the government of the People’s Republic of Bangladesh, the Canadian International Development Agency, the Swedish International Development Cooperative Agency, and the Department for International Development, UK. National Institutes of Health (grant NIH R03-AI076748) and (grant NIH 5 T32AI07001-36) National Institute of Environmental Health Sciences (grant NIEHS T32ES007018) National Science Foundation (grant NSF BCS-0924479). Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)5 R24 HD050924 and 5 T32 HD007168.