by Ann Samuel on  September 5, 2007 at 3:29 PM Environmental Health
Arsenic  In The Food Chain  - An International Threat
Calling it a 'global problem', researchers have expressed their fears over arsenic poisoning, especially in developing countries.

The scientists, speaking at the Royal Geographical Society (RGS) annual meeting in London, warned that about 140 million people, mainly from the south and east of Asia were in danger of arsenic poisoning, primarily from their drinking water. The hazards are none less than cancer, they add.

This is not all. The scientists also warn that consuming large amounts of rice grown in such affected areas could also be a health risk. "It's a global problem, present in 70 countries, probably more," Peter Ravenscroft, a research associate in geography with Cambridge University informs. "If you work on drinking water standards used in Europe and North America, then you see that about 140 million people around the world are above those levels and at risk."

What are the risks of consuming higher than permitted quantities of arsenic? According to experts, arsenic consumption can bring about higher rates of some cancers, including tumors of the lung, bladder and skin, and other lung conditions. Some of these effects can be visible only decades after the first exposure.

"In the long term, one in every 10 people with high concentrations of arsenic in their water will die from it," observes Allan Smith from the University of California at Berkeley. "This is the highest known increase in mortality from any environmental exposure". Smith adds that he is yet to see one government agency, which has, gives this problem the priority it deserves.

The first signs that arsenic-contaminated water might be a major health issue were revealed in the 1980s, when the documentation of poisoned communities in Bangladesh and the Indian state of West Bengal were made public.

In order to avoid drinking surface water, which can be contaminated with bacteria causing diarrhea and other diseases, aid agencies had been promoting the digging of wells, not realizing that well water could be tainted with elevated levels of arsenic.

While the metal is present naturally in soil, it usually leaches into groundwater; some part of the process being played by bacteria. So far, large-scale contamination has been found in other Asian countries such as China, Cambodia and Vietnam, as well as in South America and Africa.

Though it is less of a problem in North America and Europe where most water is provided by utilities, some private wells in the UK may not be tested and could present a problem, says Ravenscroft.

So, does a solution exist? Experts opine that once the threat has been identified, there are remedies, such as digging deeper wells, purification, and identifying safe surface water supplies. The scientists at the RGS meeting urge that governments should test all wells in order to assess the threat to communities. "Africa, for example, is probably affected less than other continents, but so little is known that we would recommend widespread testing," Ravenscroft was quoted.

His Cambridge team has developed computer models aimed at predicting which regions might have the highest risks, taking into account factors such as geology and climate. The scientists added that as Asian countries use water for agriculture as well as drinking, this too could be a source of arsenic poisoning.

Rice is usually grown in paddy fields, often flooded with water from the same wells. Arsenic is drawn up into the grains, which are used for food. In particular, according to Andrew Meharg from Aberdeen University, his research has shown that arsenic transfers from soil to rice about 10 times more efficiently than to other grain crops.

This is clearly a problem in countries such as Bangladesh where rice is the staple food. Professor Meharg believes this could be an issue even in the UK among communities, which eat rice frequently. "The average (British) person eats about 10g to 16g of rice per day, but members of the UK Bangladeshi community for example might eat 300g per day," he warns.

Thanks to these revelations, the UK's Food Standards Agency is currently assessing whether this level of consumption carries any risk.

Source: Medindia

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