Une équipe de recherche de l'université d'Exeter en Grande-Bretagne vient de confirmer que le pollen de cultures OGM peuvent contaminer les autres cultures sur des distances (15 kms) plus grandes qu'on ne pensait. De plus, la contamination génétique serait de 2 à 3 fois plus élevée qu'il était admis jusqu'alors. Les chercheurs recommandent un minimum de 500 mètres comme zone tampon. Et au Canada ? Les zones tampons pour les essais en champs pour de nouveaux canola OGM varient de 10 à 50 mètres. Pour le canola OGM autorisé et commercialisé ? ZÉRO. Bonjour la contamination ! [vidéo]
Alarm as GM pollen wafts way beyond the official buffer zones
By SEAN POULTER - 31st May 2007
Pollen from genetically-modified crops can spread far further than previously thought, research has shown.
The findings raise questions over whether the Government-approved 'buffer zones' around GM farms will be big enough to prevent contamination of conventional crops.
The size of these buffer zones was decided after large-scale field trials carried out across Britain over the last five years.
But now a team from the University of Exeter has called on the Department for Environment, Food and Rural Affairs to increase the zones to minimise pollen pollution.
Scientists are concerned that if contamination occurs, it could lead to the creation of 'superweeds' with an immunity to chemical sprays.
The Exeter team created a mathematical model on pollen spread using data on wind strengths from weather stations in the UK and Europe.
They found that pollen could contaminate surrounding fields at a rate two to three times higher than originally thought.
Lead researcher Martin Hoyle said: "Once you have GM crops growing, contamination of other crops will inevitably occur.
"The only question is how you minimise that to the required threshold. Spread of GM pollen on the wind is only one factor.
"There is also seed contamination and the fact that GM crops grown on a field in the past may persist among any new crops that are planted."
The study builds on research which has already found that GM pollen can fertilise conventional crops within a ten-mile radius.
The findings present the worrying possibility of vast swathes of the countryside - including organic farms - becoming contaminated by GM crops.
Critics are demanding the Government tears up its plans to allow GM farming in this country, which could start within just two years.
Friends of the Earth called for a moratorium on commercial GM farming until the risks were fully understood.
Its spokesman Clare Oxborrow said: "This new research makes clear that there are still so many gaps in our knowledge about the implications of GM farming.
"We are talking about a step that will lead to the irreversible GM contamination of the countryside-and our food.
"This technology-has been utterly rejected by the public yet ministers continue to try to steamroller ahead. This research makes clear it is time to take a step back and think again."
The Government and the EU are working on the basis that it will be legal and acceptable to allow GM contamination of other crops, including organic ones, up to a threshold of 0.9 per cent.
That means that if less than one plant in a hundred is contaminated, the entire harvest can be referred to as 'GM-free'.
That is totally unacceptable to the organic farming movement, which argues that any GM contamination is an assault on the purity of the food.
The Government is currently proposing a buffer zone of just 35metres around fields of GM oilseed rape to meet the 0.9 per cent threshold.
It claims a buffer zone of up to 58metres would be need to keep contamination below 0.1 per cent.
The Exeter research suggests, however, that a 500metre gap would be needed to ensure contamination is kept below this level.
The current plan for the buffer zone around maize is put at 110 metres. But the research suggests it may need to be seven or eight times greater.
Mr Hoyle said: "Defra will need to think about extending the separation distances used for GM crops in the light of these findings."
The research findings are published today in the journal Ecological Applications.