Well‐Switching to Reduce Arsenic Exposure in Bangladesh: Making the Most of Inaccurate Field Kit Measurements

• Published in: Geohealth Vol. 5; no. 12; pp. e2021GH000464 - n/a
• Main Authors: Jameel, Yusuf, Mozumder, M. Rajib Hassan, Geen, Alexander, Harvey, Charles F.
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.12.2021; John Wiley and Sons Inc; American Geophysical Union (AGU)
• Subjects: Aerosols; Aerosols and Particles; Arsenic; Atmospheric Composition and Structure; Bangladesh; Biogeosciences; Datasets; Drinking water; Exposure; field kit; Geohealth; Groundwater; Groundwater Quality; Households; Human Impact; Human Impacts; Hydrology; Impacts on Humans; Laboratories; Marine Pollution; Megacities and Urban Environment; Mitigation; Natural Hazards; Oceanography: Biological and Chemical; Oceanography: General; Paleoceanography; Pollution: Urban and Regional; Pollution: Urban, Regional and Global; Public Health; Space Weather; Urban Systems; Wells; well‐switching; Bangladesh; field kit; Bangladesh; arsenic; well‐switching; public health
• ISSN: 2471-1403; 2471-1403
• DOI: 10.1029/2021GH000464

Well‐switching programs in Bangladesh have successfully lowered arsenic exposure. In these programs, households switch from wells that are labeled “unsafe” to nearby wells labeled “safe,” but these designations are usually based on inherently inaccurate field kit measurements. Here, we (a) compare the efficacy of field‐kit measurements to accurate laboratory measurements for well switching, (b) investigate the potential impact on well switching of the chosen “safe” threshold, and (c) consider the possible benefits of providing more detailed concentration information than just “safe” and “unsafe.” We explore different hypothetical mitigation scenarios by combining two extensive data sets from Araihazar Bangladesh: a blanket survey of 6595 wells over 25 km2 based on laboratory measurements and 943 paired kit and laboratory measurements from the same area. The results indicate that the decline in average arsenic exposure from relying on kit rather than laboratory data is modest in relation to the logistical and financial challenge of delivering exclusively laboratory data. The analysis further indicates that the 50 μg/L threshold used in Bangladesh to distinguish safe and unsafe wells, rather than the WHO guideline of 10 μg/L, is close to optimal in terms of average exposure reduction. We also show that providing kit data at the maximum possible resolution rather than merely classifying wells as unsafe or safe would be even better. These findings are relevant as the government of Bangladesh is about to launch a new blanket testing campaign of millions of wells using field kits. Plain Language Summary Arsenic contaminates groundwater across much of Bangladesh, poisoning millions of people who rely on well water for drinking. Well‐switching programs have proved useful for lowering arsenic exposures. In well‐switching programs, households with high‐arsenic wells switch to nearby wells with low arsenic for drinking. However, several important questions remain for designing future well‐switching programs: Do inexpensive field kits provide sufficiently accurate arsenic concentration measurements for determining which wells are safe and which are unsafe? What arsenic concentration is the best threshold for designating wells as safe? In this analysis, we use two large datasets from Ariahazar Bangladesh, a district where the arsenic problem has been extensively studied. Our results indicate that the average decline in arsenic exposure for a switching program that is based on cheap kit measurements is comparable to that of a program that uses more accurate, but expensive and logistically challenging, laboratory measurements. We also show that the 50 μg/L threshold used in Bangladesh to distinguish safe and unsafe wells is close to the optimal value for reducing arsenic exposure. These findings will be useful to the government of Bangladesh that is about to launch a new blanket testing campaign of millions of wells using field kits. Key Points Well‐switching based on kit or laboratory measurements produces similar reductions in arsenic exposure The optimal well switching threshold for reducing arsenic exposure is near 50 μg/L, higher than the WHO guideline of 10 μg/L Providing actual kit readings instead of classifying wells as just "unsafe" or "safe" could lead to a higher reduction in arsenic exposure