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Drinking Water Contaminants- ARSENIC

Inorganic arsenic is a documented human carcinogen.
Based on health criteria, the guideline value for arsenic in drinking-water would be less than 0.01mg/L.
Because the guideline value is restricted by measurement limitations, and 0.01 mg/L is the realistic limit to measurement, this is termed a provisional guideline value.

The WHO Guidelines for Drinking-water Quality is intended for use as a basis for the development of national standards in the context of local or national environmental, social, economic, and cultural conditions.

A UN report on arsenic in drinking-water has been prepared in cooperation with other UN agencies under the auspices of an inter-agency coordinating body (the Administrative Committee on Coordinations Sub-committee on Water Resources. It provides a synthesis of available information on chemical, toxicological, medical, epidemiological, nutritional, and public health issues; develops a basic strategy to cope with the problem, and advises on removal technologies and on water quality management.

As part of WHO's activities on the global burden of disease, an estimate of the disease burden associated with arsenic in drinking-water is in preparation. A report entitled "Towards an assessment of the socioeconomic impact of arsenic poisoning in Bangladesh" was released in 2000.

A United Nations Foundation grant for 2.5 million approved in July 2000, will enable UNICEF and WHO to support a project to provide clean drinking-water alternatives to 1.1 million people in three of the worst affected sub-districts in Bangladesh. The project utilizes an integrated approach involving communication, capacity building for arsenic mitigation of all stakeholders at subdistrict level and below, tube-well testing, patient management, and provision of alternative water supply options.

URGENT REQUIREMENTS

Large-scale support to the management of the problem in developing countries with substantial, severely affected populations.
Simple, reliable, low-cost equipment for field measurement.
Increased availability and dissemination of relevant information.
Robust affordable technologies for arsenic removal at wells and in households.

GLOBAL SITUATION

The delayed health effects of exposure to arsenic, the lack of common definitions and of local awareness as well as poor reporting in affected areas are major problems in determining the extent of the arsenic-in-drinking-water problem.

Reliable data on exposure and health effects are rarely available, but it is clear that there are many countries in the world where arsenic in drinking-water has been detected at concentrations greater than the Guideline Value, 0.01 mg/L or the prevailing national standard. These include Argentina, Australia, Bangladesh, Chile, China, Hungary, India, Mexico, Peru, Thailand, and the United States of America. Countries, where adverse health effects have been documented, include Bangladesh, China, India (West Bengal), and the United States of America. Examples are:

Seven of 16 districts of West Bengal have been reported to have ground water arsenic concentrations above 0.05 mg/L; the total population in these seven districts is over 34 million (Mandal, et al, 1996) and it has been estimated that the population actually using arsenic-rich water is more than 1 million (above 0.05 mg/L) and is 1.3 million (above 0.01 mg/L) (Chowdhury, et al, 1997).
According to a British Geological Survey study in 1998 on shallow tube-wells in 61 of the 64 districts in Bangladesh, 46% of the samples were above 0.010 mg/L and 27% were above 0.050 mg/L. When combined with the estimated 1999 population, it was estimated that the number of people exposed to arsenic concentrations above 0.05 mg/l is 28-35 million and the number of those exposed to more than 0.01 mg/l is 46-57 million (BGS, 2000).
Environment Protection Agency of The United States of America has estimated that some 13 million of the population of the USA, mostly in the western states, are exposed to arsenic in drinking- water at 0.01 mg/L, although concentrations appear to be typically much lower than those encountered in areas such as Bangladesh and West Bengal. (USEPA, 2001)

Information extracted from:
Guidelines for drinking-water quality, 2nd ed.
Geneva, World Health Organization, 1996.