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In South America, Argentina and Chile are affected. There are also many locations in the United States where the groundwater contains arsenic concentrations in excess of the [[United States Environmental Protection Agency|Environmental Protection Agency]] standard of 10 parts per billion adopted in 2001. According to a recent film funded by the US Superfund, {{cite web |url=http://www.youtube.com/watch?v=hi5DfRy01vE |title=In Small Doses |format= |work= |accessdate=}}, millions of private wells have unknown arsenic levels, and in some areas of the US, over 20% of wells may contain levels that are not safe.
==Health effects of arsenic==
Consuming water contaminated by arsenic can cause [[skin cancer|skin]], and [[bladder cancer|bladder]] as well as [[cardiovascular disease]].{{citation needed|date=December 2011}}
Some research concludes that even at the lower concentrations, arsenic contamination is a major causes of death. A study conducted in a contiguous six-county area of southeastern Michigan investigated the relationship between moderate arsenic levels and 23 selected disease outcomes. Disease outcomes included several types of cancer, diseases of the circulatory and respiratory system, diabetes mellitus, and kidney and liver diseases. Elevated mortality rates were observed for all diseases of the circulatory system. The researchers acknowledged a need to replicate their findings.<ref>, Jaymie R. Meliker, [http://www.ehjournal.net/content/6/1/4 ''Arsenic in drinking water and cerebrovascular disease, diabetes mellitus, and kidney disease in Michigan: a standardized mortality ratio analysis''] Environmental Health Magazine. Volume 2:4. 2007. Accessed 9 Sept. 2008.</ref>
Arsenic contamination of the groundwater in Bangladesh is a serious problem. Prior to the 1970s, Bangladesh had one of the highest infant mortality rates in the world. Ineffective water purification and sewage systems as well as periodic monsoons and flooding exacerbated these problems. As a solution, UNICEF and the World Bank advocated the use of wells to tap into deeper groundwater. Millions of wells were constructed as a result. Because of this action, infant mortality and diarrheal illness were reduced by fifty percent. However, with over 8 million wells constructed, approximately one in five of these wells is now contaminated with arsenic above the government's drinking water standard.
In the [[Ganges Delta]], the affected wells are typically more than 20 m and less than 100 m deep. Groundwater closer to the surface typically has spent a shorter time in the ground, therefore likely absorbing a lower concentration of arsenic; water deeper than 100 m is exposed to much older sediments which have already been depleted of arsenic.<ref>{{cite journal
| title = Chemistry of arsenic in groundwater of Ganges-Brahmaputra river basin
| author = Singh A. K.
}}</ref> The study conducted in Bangladesh involved the analysis of thousands of water samples as well as hair, nail, and urine samples. They found 900 villages with arsenic above the government limit.
Criticism has been leveled at the [[Aid agency|aid agencies]], who denied the problem during the 1990s while millions of [[tube well]]s wells were sunk. The aid agencies later hired foreign experts who recommended treatment plants that were inappropriate to the conditions, were regularly breaking down, or were not removing the arsenic.<ref>[[New Scientist]], [http://www.newscientist.com/article/mg19025450.600.html Interview: Drinking at the west's toxic well] 31 May 2006.</ref>
In West Bengal, India, water is mostly supplied from rivers. Groundwater comes from deep tubewells, which are few in number. Because of the low quantity of deep tubewells, the risk of arsenic patients in West Bengal is comparatively less.<ref name=timesofindia>[[The Times of India]], [http://timesofindia.indiatimes.com/articleshow/864169.cms 'Use surface water. Stop digging'], interview, 26 Sep, 2004.</ref> According to the World Health Organisation, “In Bangladesh, West Bengal (India), and some other areas most drinking-water used to be collected from open dug wells and ponds with little or no arsenic, but with contaminated water transmitting diseases such as diarrhoea, dysentery, typhoid, cholera, and hepatitis. Programmes to provide ‘safe’ drinking-water over the past 30 years have helped to control these diseases, but in some areas they have had the unexpected side-effect of exposing the population to another health problem—arsenic.”<ref name=who>[[World Health Organization]], [http://www.who.int/mediacentre/factsheets/fs210/en/index.html Arsenic in Drinking Water], accessed 5 Feb 2007.</ref>