Arsenic contamination of groundwater

Arsenic contamination of groundwater is a form of groundwater pollution which is often due to naturally occurring high concentrations of arsenic in deeper levels of groundwater. It is a high-profile problem due to the use of deep tubewells for water supply in the Ganges Delta, causing serious arsenic poisoning to large numbers of people. A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water. The problem became serious health concern after mass poisoning of water in Bangladesh. Arsenic contamination of ground water is found in many countries throughout the world, including the US. Arsenic contamination of groundwater is a form of groundwater pollution which is often due to naturally occurring high concentrations of arsenic in deeper levels of groundwater. It is a high-profile problem due to the use of deep tubewells for water supply in the Ganges Delta, causing serious arsenic poisoning to large numbers of people. A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water. The problem became serious health concern after mass poisoning of water in Bangladesh. Arsenic contamination of ground water is found in many countries throughout the world, including the US. Approximately 20 major incidents of groundwater floarsenic contamination have been reported. Of these, four major incidents occurred in Asia, in Thailand, Taiwan, and Mainland China. Locations of potentially hazardous wells have been mapped in China. Arsenic contaminated water typically contains arsenous acid and arsenic acid or their derivatives. Their names as 'acids' is a formality; these species are not aggressive acids but are merely the soluble forms of arsenic near neutral pH. These compounds are extracted from the underlying rocks that surround the aquifer. Arsenic acid tends to exist as the ions 2− and − in neutral water, whereas arsenous acid is not ionized. 66% of 1200 samples tested contained arsenic above WHO recommended limit, threatening over 60 million residents. 50–60 million residents consume water with arsenic levels greater than 50 micrograms of arsenic per liter, levels far passing acceptable levels worldwide. Bangladesh is the most affected country by arsenic poisoning through drinking water. Government and other agencies like UNICEF installed wells to provide fresh water in underdeveloped areas of Bangladesh, but later found disease related to consumption of this water. About 7–11 million wells or hand pumped wells are providing arsenic polluted water to local people. In 2008, approximately 57 million residents used water contaminated with arsenic from these shallow wells. 20% of the total deaths are related to arsenic related cancer. An analysis of water and food consumption in Socaire, a rural village in Chile, found that between November 2008 and September 2009, the total intake of arsenic by the villagers correlated with the amount of water and local produce consumed.