Arsenic in Water: when the road to hell is paved with good intentions

, by  Larbi Bouguerra

A lot of the wells which have been bored in Bangladesh to enhance access to drinking water and protection against such dieases as cholera have been revealed to be contaminated by significant amounts of arsenic. This situation, which is not restricted to Bangladesh, demonstrates how necessary it is to chose adequate locations and constantly monitor water quality.

Specialists estimate that there are 450 million people who suffer from water shortage in the world and they are of the opinion that this figure will increase, given the predicted demographic growth. Where water does indeed exist, it is frequently not drinkable, generally because it is contaminated. The WHO (World Health Organisation) estimates that at global level, there are 1.2 billion people with no access to drinking water, and 2 million children die every year from drinking contaminated water.

Epidemics of cholera – a disease with diarrhoea that is caused by the contamination of surface water by the Vibrion choleræ bacteria – have caused a lot of deaths in Bangladesh. In order to avoid this, deep wells were bored in the 1950 and 60s, on the lines of the example set by the British colonialists in the 1930s. There was an unfortunate – and quite involuntary – consequence. The groundwaters contained hundreds of milligrams of arsenic per litre - of natural geological origin – a dilution that is far higher than the standard international norm of 10 micrograms per litre set by the WHO. It is reckoned that quarter of the population of Bangladesh drinks water that contains a 10 to 15 times greater concentration of arsenic than the international norm. Drinking water with such a high arsenic content over a number of years leads to many serious health problems, often skin-related, such as chronic dermatitis, hyperkeratosis, “black foot disease”, a type of skin cancer where the skin of the lower limbs is affected, and which now affects about 20 million people in the country, as well as cancer of the bladder and the lungs. These affections are caused by geologically present arsenic, and also occur in India (West Bengal in particular) as well as in China.

But the contamination of water by arsenic is not a phenomenon limited to the Indian subcontinent. In some regions of the USA, the tap water fails to meet the new norm pf 10 micrograms/litre, as set by the Environmental Protection Agency (EPA). The old norm that was applied until 2001 was 50 micrograms/litre.

The WHO considers that water contamination by arsenic affects tens of millions of people in over 20 countries around the world (the Lagunera Region in Mexico, the Codoban in Argentina, inner Mongolia, Taiwan, Finland, and San Pedro de Atacama in Chile...).


This problem proves that it is necessary to bore wells with sufficient geological awareness, after carrying out studies, and to bore to a depth of over two hundred meters, as the analysis of water chemistry has shown. In some regions, a large amount of arsenic is naturally present in the earth, as in Cornwall in the United Kingdom or in the Reporoa district in New Zealand (the hot water springs of Waiotapu). Nor is arsenic the only issue, even if it strikes the imagination of most people, given its use as a poison by criminals throughout the ages. Some wells in Niger have a water content that is too rich in fluoride, and this water causes serious diseases of the bones. It is all the more necessary to carry out these analyses, as these elements (lead, nitrates, heavy metals, radioactive elements...) generally show up over a long period of time.

It is necessary to insist that this element is present, as we have already stated, in many countries of the world, and that in North America it is found not only in the United States, but also in Canada, where it has been detected in the waters of the Athabasca river that provides the town of Calgary with water, as reported by the Quebec newspaper Le Devoir (April 2006).

In the United States, President Clinton, just before leaving the White House, introduced an Executive Order to introduce the norm of 10 µg/l, which is applied in al the industrialised countries, and replace that of 50µg/l that had been applied in the United States since 1942. But in March 2001, President Bush refused to implement this decision, although he did concede in January 2006, following the pressure that was brought to bear by the American Academy for Science; the reason for his hesitation was that he did not wish to undermine the interests of major contributors to his electoral campaign fund, in particular the owners of mines (copper, lead, gold...). The wastewater from these mines contains arsenic, which is released into the surface waters by the rain run-off. They also include contamination from the forests that are treated to protect the wood from wood-eating insects. It also contains coal tar from the coal-powered electricity generating stations in the Appalachian Mountains, whose ashes and smoke emissions contain this substance...

Several easy-to-use chemical processes have been developed to make water that contains less than 50 µg/l of arsenic fit for human consumption. Professor Abul Hussam of the George Mason University of Virginia invented a method that is remarkably simple to use and also low cost. In 2005 he was awarded the Grainger Challenge prize of a million dollars by the National Academy of American engineers for his work.

Jan Roelof van Meer of the Swiss Federal Institute for Science of the Environment and Technology has also developed a method for detecting arsenic in water in even very low concentrations. It is based on a modified line of E. Coli bacteria that emits green fluorescent light if the poison exceeds 4 ppb.

Finally, it is worth noting that in 2002 certain villages in Bangladesh took legal action against the British government’s Geological Services (BGS) that had been responsible for supervising the well-water since 1992, but had failed to carry out any analysis to detect arsenic. They initially won the case, but the ruling was later overturned in an appeal in February 2004. This same Service did not detect the very high level of water contamination in wells in Hanoi in Vietnam in 1996, which was later found by Swiss researchers in 2002.

- John Emsley, The Elements of Murder. A History of Poison, Oxford University Press, Oxford, 2005.
- Patricia L. Short, «Keeping it clean», Chemical and Engineering News, organe de l’American Chemical Society, Washington, D.C. ; April 13th 2007, p.13- 20.

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