Arsenic contamination in groundwater has been reported in more than 20 countries around the world and, in many, shallow groundwater is used for both drinking and irrigation purposes. Natural arsenic in groundwater at concentrations above the drinking water standard of 10 µg/liter is not uncommon, and the realization that water resources can contain insidious toxic concentrations of naturally-occurring chemical constituents, such as arsenic, is fairly recent and increasingly urgent.
Estimates of arsenic toxicity (arsenosis) from drinking water, causing skin lesions and various types of cancers, indicate about 130 million people are impacted (Nordstrom 2002, Nickson et al. 2005). Man-made sources of arsenic, such as mineral extraction and processing wastes, poultry and swine feed additives, pesticides and highly soluble arsenic trioxide stockpiles are also not uncommon and have further caused the contamination of soils and groundwaters.
Studies spurred from the initial FAO study in Bangladesh, with UNDP funding in 2001 on arsenic transference in rice, continue to raise concerns of arsenic accumulation and food safety from long-term use of arsenic-laden groundwater for irrigation.