World facing 'arsenic timebomb' in their drinking water
Pastor Dale Morgan
Last Updated: Thursday, 30 August 2007, 09:13 GMT 10:13 UK
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World facing 'arsenic timebomb' in their drinking water*
By Richard Black
Environment correspondent, BBC News website
About 140 million people, mainly in developing countries, are being
poisoned by arsenic in their drinking water, researchers believe.
Speaking at the Royal Geographical Society (RGS) annual meeting in
London, scientists said this will lead to higher rates of cancer in the
future.
South and East Asia account for more than half of the known cases globally.
Eating large amounts of rice grown in affected areas could also be a
health risk, scientists said.
"It's a global problem, present in 70 countries, probably more," said
Peter Ravenscroft, a research associate in geography with Cambridge
University.
"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."
Testing time
Arsenic consumption leads to higher rates of some cancers, including
tumours of the lung, bladder and skin, and other lung conditions. Some
of these effects show up decades after the first exposure.
I don't know of one government agency which has given this the priority
it deserves-Allan Smith
"In the long term, one in every 10 people with high concentrations of
arsenic in their water will die from it," observed Allan Smith from the
University of California at Berkeley.
"This is the highest known increase in mortality from any environmental
exposure."
The international response, he said, is not what the scale of the
problem merits.
"I don't know of one government agency which has given this the priority
it deserves," he commented.
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.
Rice plants absorb arsenic from the soil as they grow
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.
It is less of a problem in North America and Europe where most water is
provided by utilities. However, some private wells in the UK may not be
tested and could present a problem, Mr Ravenscroft said.
Problems abroad
Once the threat has been identified, there are remedies, such as as
digging deeper wells, purification, and identifying safe surface water
supplies.
As a matter of priority, scientists at the RGS meeting said, 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," said
Peter Ravenscroft.
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.
Arsenic contamination can be a problem in parts of the US
"We have assessments of the Ganges and Brahmaputra river basins, for
example, and then we look for similar basins elsewhere.
"There are similar areas in Indonesia and the Philippines, and very
little evidence of tests; yet where there has been some testing, in (the
Indonesian province of) Aceh for example, signs of arsenic turned up."
Asian countries use water for agriculture as well as drinking, and this
too can 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.
Andrew Meharg from Aberdeen University 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, and Professor Meharg believes it 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 said.
The UK's Food Standards Agency is currently assessing whether this level
of consumption carries any risk.