Part Four - Arsenic in Groundwater Across the World

The extent of the arsenic problem worldwide is as yet unknown. Before arsenic was identified as the unambiguous cause of wide-scale health problems in Bangladesh, such occurrences were considered relatively isolated. However, since the 1990s, efforts by governments, external support agencies, and academic institutions to identify other potential contamination areas have dramatically increased.[32] Although it is far too early to outline definitively the extent of the problem globally, it is clear that there are many countries in the world where arsenic in drinking water has been detected at concentrations greater than the WHO guideline value (10 mg/L) or the prevailing national standard.[33]

Figure 4.1: Documented Cases of Arsenic Problems in Groundwater Related to Natural Contamination

Source: British Geological Survey, 2001, http://www.bgs.ac.uk/.

Distinctive groundwater arsenic problems result both from natural sources (in reducing as well as in oxidizing groundwater conditions) and from anthropogenic activities (mining, for example). Arsenic associated with geothermal waters has also been reported in several countries. Table 4.1 below summarizes the state of arsenic contamination in different countries around the globe.[34]

Table 4.1: Arsenic Contamination across the Globe

Country	Origin of arsenic	First identified	Affected region	Range of contamination	Population exposed
Argentina	Natural, due to the soil composition polluting the shallow well waters. Also high content in some river waters.	Beginning of the 19^th century	The Chaco-Pampean Plain of Central Argentina, covering around one million sq. km.	Groundwater arsenic concentration in some places ranges from 100 to 2000 mg/L	200,000
Bangladesh	Natural origin, deriving from the geological strata underlying Bangladesh	1993	61 out of 64 districts	Less than 0.25 mg/L to more than 1600 mg/L	Up to 57 million are drinking water with an arsenic concentrations greater than the WHO guideline value, and up to 35 million drinking water with concentrations in excess of the Bangladesh standard
Chile	Associated with quaternary volcanism in the sparsely populated and arid Central Andean Codilleras	1962	Arica Province in north Chile	Not available	400,000 over an area of 125,000 sq. km.
China	Natural, in reducing environment	First identified in Xinjiang Province in early 1980s	Inner Mongolia Shaanxi and Xinjiang Provinces	90% of the wells tested had arsenic at level higher than 50 mg/L (highest concentration detected was 2400 mg/L)	600,000 in China and 1.1 million in Inner Mongolia
Ghana	Effects of mining activities and possibly some arsenopyrite oxidation	Not available	Obuasi	Some shallow wells and streams contain low to high concentration	100,000

Hungary and Romania	Natural	Not available	Southern part of the Great Hungarian Plain and parts of neighboring Romania	2 to 176 mg/L	400,000
India	Geological origin, analogous to the problem in Bangladesh	Resultant health effects were first identified in late 1980s	West Bengal (8 out of 17 districts) Also suspected occurrence in Bihar, Gangetic and Brahmaputra plains	Not available	Over 5 million. Estimated 300,000 people are suffering from various stages of arsenicosis
Mexico	Natural. volcanic sediment type aquifer having oxidizing, neutral to high pH groundwater condition	Not available	Lagunera Region of north central Mexico. Affected area expands up to 32,000 sq. km. Northern region is also believed to have arsenic contamination.	1 to 500 mg/L (average 100 mg/L)	400,000
Nepal	Not known, but believed to be natural	Late 1990s. When the gravity of the problem in India and Bangladesh was identified, water experts in Nepal decided it was time to look into the quality of water supply there.	20 Terai districts in the plains of Nepal	Not available	550,000 people (2.4% of population) exposed to arsenic exceeding 50 mg/L and 3.19 million (13.6% of population) exposed to arsenic exceeding 10 mg/L

Taiwan	Natural. The contaminated aquifer is sediment type with shale. Contamination is analogous to the one of Bangladesh and West Bengal.	1968	Southwest and north coastal zones	In some areas, concentration of arsenic is as high as 1800 mg/L	200,000
Thailand	Oxidation of arsenopyrite from former tin mining.	1996	Southeast Asian Tin Belt, in and close to Ron Phibun town. Affected area is around 100 sq. km.	1 to 500 mg/L	Not available
The United States	Natural occurrences in groundwater (in both reducing and oxidizing environments. There are also areas where arsenic comes from geothermal sources and mining related activities	Not available	Southwestern states of Nevada, California and Arizona. Arsenic associated with geothermal sources occurs in certain areas in California, Nevada and Los Angeles. Some areas in Alaska, California, Nevada, and South Dakota have arsenic arising from mining activities.	Varied	The Environmental Protection Agency of the United States has estimated that some 13 million are exposed to arsenic in drinking water at 10 mg/L
Vietnam	Due to toxic condition of the aquifer	Very recently	Mekong and Red River delta region, including Hanoi.	On an average, 430 mg/L in most affected district.	Not available

From the above observations, it is clear that arsenic contamination of groundwater exists in many parts of the world, but Bangladesh is the country where the problem is most acute, with the lives of millions of people at stake.

[32] World Health Organization, United Nations Synthesis Report on Arsenic in Drinking Water, 2003, http://www.who.int/ water_sanitation_health/dwq/arsenic3/en/.

[33] World Health Organization, Arsenic in Drinking Water, WHO Fact Sheet No. 210 (Geneva: WHO, revised May 2001).

[34] This portion has been collated from the following sources: World Health Organization, United Nations Synthesis Report on Arsenic in Drinking Water, 2003, http://www.who.int/water_sanitation_health/dwq/arsenic3/en/; D.G. Kinniburgh and P.L. Smedley, eds., Arsenic Contamination of Groundwater in Bangladesh, British Geological Survey Report, Volume 2 (Keyworth, Nottingham: British Geological Survey, 2001); Sirajul Islam, ed., Banglapedia: National Encyclopedia of Bangladesh (Asiatic Society of Bangladesh, March 2003); Md. Harun-ur-Rashid and Md. Abdul Karim Mridha, “Arsenic Contamination of Groundwater in Bangladesh” (paper presented at the 24^th WEDC Conference, Islamabad, Pakistan, 1998); World Health Organization, Arsenic in Drinking Water, WHO Fact Sheet No. 210 (Geneva: WHO, revised May 2001).