September 2007
Water, Water Everywhere, But Not A Drop To Drink
Naturally-occurring arsenic in drinking water poses a growing global health risk as large numbers of people unknowingly consume unsafe levels of the chemical element, researchers have warned.
The problem is bigger than scientists had thought and affects nearly 140 million people in more than 70 countries, according to new research presented at the annual Royal Geographical Society meeting in London.
Arsenic can cause lung disease and cancers, even long after people stop drinking contaminated water, said Peter Ravenscroft, a researcher at the University of Cambridge. Arsenic consumption also leads to higher rates of some cancers, including tumours of the lung, bladder and skin, and other lung conditions with some of these effects showing up only decades after the first exposure.
"What is new is the extent of arsenic pollution is much bigger than people realised," Ravenscroft said in an interview. He continued: "there is a very important connection between arsenic in water and arsenic in food, especially where people grow irrigated corps."
World Health Organisation guidelines set a safe limit of 10 parts per billion of arsenic in water supplies but tens of millions of people in the world drink unsafe water above that level, researchers said.
At present, Bangladesh is the worst-affected country. There, hundreds of thousands of people are at risk from dying of arsenic poisoning claim scientists.
Arsenic has also been found in the water in developed countries and industrial activities such as mining can also lead to contamination. The first signs that arsenic-contaminated water might be a major health issue emerged in the 1980s, with the documentation of poisoned communities in Bangladesh and the Indian state of West Bengal. In order to avoid drinking surface water, which can be contaminated with bacteria causing diarrhoea and other diseases, aid agencies had been promoting the digging of wells, not suspecting that well water would emerge with elevated levels of arsenic. The metal is present naturally in soil, and leaches into groundwater, with bacteria thought to play a role. Since then, large-scale contamination has been found in other Asian countries such as China, Cambodia and Vietnam, in South America and Africa.
Rising awareness has led to increased testing that has revealed more widespread arsenic in drinking water but other researchers said even more must be done to address the problem. Allan Smith, a researcher at the University of California, Berkeley and adviser to the WHO on arsenic sounded a note of concern, stating that "most countries have some water sources with dangerous levels of arsenic, but only now are we beginning to recognise the magnitude of the problem." Only time will tell how much of a problem we really face.
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