Arsenic winding up in Asian rice crops
Updated
Less than a decade ago it was thought that people exposed to drinking elevated levels of arsenic in groundwater were confined to those living in West Bengal in India and Bangladesh.
Although today this region is the epicentre of what has become recognised as 'the biggest mass poisoning of humans ever known' high levels of arsenic are now being found contaminating the groundwater in Cambodia, Vietnam and Taiwan. This environmental disaster is not confined to drinking contaminated water. Research has now found that the uptake of arsenic by crops such as rice is compounding the problem.
Presenter: Adrian Page
Speakers: Professor Andrew Meharg, University of Aberdeen
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ADRIAN PAGE: I'm with a group of farmers in a rural location in West Bengal, close to the Bangladesh border. Professor Moulic is a retired principal from a local college and is acting as my interpreter. This gentleman here, who looks as though he's really suffering very, very badly from arsenicosis, what symptoms has he got?
PROFESSOR MOULIC: He has got melanosis, severe kelatosis.
ADRIAN PAGE: How long has he been drinking the water here?
MOULIC: About 20 years.
ADRIAN PAGE: These very, very badly cracked feet which he now has, which look very, very painful - this has all come from drinking that water?
MOULIC: Yes, all these problems are come from the water.
ADRIAN PAGE: Are there many people in this village suffering from arsenicosis?
MOULIC: About 100 people are affected by this disease.
ADRIAN PAGE: The irrigation tube well is now bursting into action. Professor Moulic, irritation tube wells do allow farmers to irrigate their crops throughout the year, but are they aware of the risks they face from arsenic poisoning?
MOULIC: They have got no other alternative because they will have to grow food at any cost, so though arsenic is there, they are continuing it.
ADRIAN PAGE: Because there is no alternative?
MOULIC: Yes, yes, because there is no alternative.
ADRIAN PAGE: Elevated levels of arsenic in groundwater are now being found in more and more countries around the world, particularly in the South-East Asia region. Indications are that the risk of exposure to arsenic poisoning is not just confined to drinking arsenic-contaminated water via hand tube wells, but also from crops, such as rice. Andrew Meharg is Professor of Biogeochemistry at Aberdeen University in Scotland. He has been at the forefront of the research regards the uptake of arsenic by crops, particularly rice.
ANDREW MEHARG: In terms of food, they haven't set food standards and there's no modern food standards set, really, except for some countries in South-East Asia which now realise there's a problem with arsenic in rice. And so China, for example, has set modern food standards which are an awful lot more stringent than what you'd get -
ADRIAN PAGE: Do you know what those standards?
ANDREW MEHARG: It's 0.15 in China - milligram per kilogram.
ADRIAN PAGE: What are we finding in rice today?
ANDREW MEHARG: It depends where you get your rice from. In Bangladesh, where they're irrigating rice with contaminated tube well water, we can find an average 0.3 milligram per kilogram. It's actually apparent that for most of the world - the majority of our arsenic intake is coming from rice. And it's at levels that would be considered unsafe in Western Europe or the USA.
ADRIAN PAGE: As a scientist, it must be a very interesting subject to work on, but being at the back of your mind you know that people are suffering very badly from arsenicosis, do you find that it keeps the pressure on?
ANDREW MEHARG: The main thing at the moment is getting people to realise there's a problem. I can't do anything. I could sit here and, like scientific colleagues around the world, come up with a perfectly beautiful model of how arsenic is taken, metabolised and transported by plants, but unless people actually say arsenic in rice is a problem and international regulators and governments spring into action, nothing will be done about it. The problems in South-East Asia - it's just grown exponentially. It's not Bangladesh, it's not west Bengal it's Cambodia, Vietnam, Taiwan. It's now Pakistan, Nepal, China's now got these areas of groundwater elevation. If you look at India alone, we've concentrated on the Bengal delta. Before the deltas, all the way up along the Ganges, along the Brahmaputra in the east, all along the flood plain - arsenic affected, arsenic affected, arsenic affected, arsenic affected. Between the Gangetic and Brahmaputra plain has the highest population density of anywhere in the planet, I think. I think it's 500 million people live in that region, all accessing arsenic-contaminated groundwater as a resource.
