Arsenic contamination in groundwaters in Bangladesh and options of sustainable drinking water supplies

Groundwater sources used for drinking in many parts of the world contain geogenic arsenic (As) with levels of concentrations above the drinking water guideline value of the World Health Organisation (WHO, 10 iJg L-1). Occurrence of arsenic in groundwater has been known a century ago from Argentina, where the toxic effects on public health were described already in the year 1917. However, it was not before half a century later, that the As problem achieved world interest. This was the consequence of a UNICEF program to provide the rural population of Bangladesh with microbe-free drinking water by changing the drinking water resource from surface- and rainwater to groundwater exploited from shallow aquifers. However, the quality of the groundwater was not tested for As and caused, after 10 years of exposure of large parts of the population, toxicological effects. This became the beginning of extended international aid efforts to mitigate the As problem in Bangladesh and adjacent West-Bengal, India, where many treatment methods have been developed and tested, and brought the groundwater As topic to wide scientific and public interest. Since several decades, the contamination of groundwater and to less extent of surface water by geogenic As is well known from countries such as Mexico, Chile, Peru, Taiwan and some small regions in European countries such as Hungary. Until recently, it was thought that the problem is limited to these countries. However, there were many new discoveries all over the world such as in several regions of the People's Republic of China (1993- 1996), Nicaragua (1996), Chhattisgarh, India (1999), Nepal (2000), Bolivia (2001) , Thailand (2001), Vietnam (2001), Australia (2001); Bihar, India (2002), Uttar Pradesh, India (2003), Jharkhand, India (2004), Assam, India (2004) , Myanmar (2004), Cambodia (2004), Pakistan (2005), El Salvador (2005), Ecuador (2005), Honduras (2006), Baja California State, Mexico (2006), Lao People's Democratic Republic (2006), Cambodia (2007), Manipur, India (2007), and more recently in Sumatra, Indonesia (2009) and Izmir province, Turkey (2009) (Fig. 1.1 in chapter 1 of this book)