Fendorf et al. (2010) Science 328: 1123-1127
‘The largest poisoning of a population in history’ is the conclusion of Smith et al. (2000) in their WHO document on arsenic (As) contamination in Bangladesh. Arsenicosis from chronic consumption of the contaminated water affects virtually all organs and tissues where skin lesions, bronchitis, gastroenteritis and ultimately a range of cancers are typical pathologies. Although arsenic contamination of drinking water is a global problem, it most seriously affects on the order of 100 million people in some of the poorest regions on earth including India/West Bengal, Bangladesh and Nepal. From the Himalayas to river basins in Southeast Asia, arsenic contamination of groundwater has become a major health problem, largely due to the proliferation of shallow tube wells installed to provide clean, pathogen-free drinking water (see for example Thakur et al. 2011; Panthi et al., 2006; Fendorf et al., 2010).
In Nepal alone there are an estimated 400,000 tube wells and in the most populated areas, about 8% of which are thought to be contaminated with arsenic. The population size of Nepal is 23.4 million people and studies by UNICEF and the Nepal Red Cross Society estimate that 2.6% of the population suffers from some level of arsenicosis. The geology of this region in combination with anaerobic microbial dissolution of normally stable iron oxide/arsenic complexes leads to chemical reduction and release of As(V) and As(III). These forms of arsenic are soluble in water and also bioavailable, readily taken up by living cells including bacteria and human tissues. Importantly, groundwater flow systems range in scale from tens of meters to hundreds of kilometers and are affected by seasonal changes (monsoon/dry-season) and irrigation so arsenic concentrations are expected to vary over location and time (Fendorf et al. 2010). Collectively these observations suggest the need for a robust, simple and inexpensive method to continuously monitor arsenic in drinking water.
Fendorf, S, Michael HA, van Geen, A (2010) Spatial and temporal variations of groundwater arsenic in South and Southeast Asia. Science 328, 1123-1127
Panthi, SR, Sharma, S, Mishra, AK (2006) Recent status of arsenic contamination in groundwater of Nepal-A review. Kathmandu U. J Sci Eng Tech 2, 1-11
Smith, AH, Lingas EO, Rahman, M (2000) Contamination of drinking-water by arsenic in Bangladesh: a public health emergency. Bull. WHO 78: 1093-1103
Thakur, JK, Thakur, RK, Ramanathan, AL, Kumar, M, Singh SK (2011) Arsenic contamination of groundwater in Nepal-An overview. Water 3, 1-20