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Arsenic: An Abundant Natural Poison
(Released March 2009)

  by Andreas Saldivar & Vicki Soto  


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In 1958, The World Health Organization (WHO) set the first International Drinking Water Standard for arsenic concentration at 200 µg/L (micrograms of arsenic per liter of water). In 1963, the World Health Organization recommended lowering the International Drinking Water Standard from 200 to 50 µg/L. The current World Health Organization provisional guideline was lowered to 10 µg/L in 1993. While this limit is recommended, it is not mandatory. Guidelines and their enforcement in specific countries are set by the individual countries. Most developed countries follow the current recommended limit, but many developing countries' national drinking water guidelines remain at the 50 µg/L limit due to the high costs of monitoring and compliance to the lower level. Guidelines can range from 7 µg/L in Australia to the former WHO guideline of 50 µg/L in Bangladesh, India, China and Nepal. (World Bank 2005)

In the United States, the Public Health Service set the first drinking water standard of 50 µg/L in 1942. In 1975 the U.S. Environmental Protection Agency (EPA) adopted this as an interim standard. Amendments to the Safe Drinking Water Act of 1996 required the EPA to promulgate a final standard for arsenic by 2001, at which time it issued the final rule for the drinking water standard or maximum contaminant level (MCL) for arsenic at 10 µg/L to lower the risk of yearly cancer occurrences. Even though the new MCL was published in 2001, public drinking water supplies had until 2006 to be compliant. (Tiemann 2007) (U.S. Environmental Protection Agency 2001)

Go To Case Studies: Bangladesh & USA

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