Impact on arsenic exposure of a growing proportion of untested wells in Bangladesh

A household drinking water survey of 6646 households was conducted in Singair upazilla of Bangladesh. A subset of 795 untested wells used by 1000 randomly selected households was tested in the field by trained village workers with the Hach EZ kit, using an extended reaction time of 40 min, and in the laboratory by high-resolution inductively-coupled plasma-mass spectrometry (HR ICP-MS).The household survey shows that more than 80% of the wells installed since the national testing campaign in this area were untested. Less than 13% of the households with untested wells knew where a low-As well was located near their home. Village workers using the Hach EZ kit underestimated the As content of only 4 out of 795 wells relative to the Bangladesh standard. However, the As content of 168 wells was overestimated relative to the same threshold.There is a growing need for testing tubewells in areas of Bangladesh where As concentrations in groundwater are elevated. This could be achieved by village workers trained to use a reliable field kit. Such an effort would result in a considerable drop in As exposure as it increases the opportunities for well switching by households.Elevated exposure to inorganic arsenic (As) is associated with cancers of the skin, bladder, and lung [1-3], reproductive and developmental effects [4,5], cardiovascular disease [6,7], and skin lesions [8,9]. In Bangladesh, millions of people are exposed to naturally occurring As concentrations that exceed the World Health Organization (WHO) guideline of 10 μg/L [10]. During the 1970s, the United Nations Children's Fund, through the government of Bangladesh, promoted the installation of tubewells to reduce risks from drinking microbial contaminated surface water [11]. In the early 1990s, evidence began to emerge that Bangladeshi villagers were presenting signs of arsenicosis due to the consumption of well water with elevated levels of As [12]. An As testing campaign relying on field kits and targeting 5 milli