In the Czech Republic (and probably not only here) the pressure groups like Greenpeace are fighting against Bt corn using the flag of organic farmers. They are telling the story that one grain of pollen transferred by wind many miles may bring disaster to organic farmer. As usually with the pseudo-religious dogmas of these groups the reality is different.
Let us read the facts collected in Spain:
The Institute for Research on Agronomic Techniques (IRTA) at Lleida, Catalonia, Spain presented the first European study on genetic modification (GM) co-existence last March. These findings were based on practical results obtained in field trials with maize, which were carried out in 2003 near Invars d'Urgell. In these field tests, the researchers observed the interaction between the Bt-maize variety "Compa CB" (Bt-176) and the isogenic conventional maize variety "Brasco".
Results showed that a separation distance of 25 meters between fields with GM and non-GM crops was sufficient to ensure that the transgenic content in the conventional produce remained below the required European Commission (EC) labeling threshold of 0.9% GM content. However, this recommended safety distance was valid only for acreages above one hectare.
In smaller fields, and in areas of GM cultivation directly adjacent to conventional plantings, the EC labeling threshold was exceeded, especially in the main wind direction. This was also observed in strips up to 10 meters wide between fields of GM and non-GM maize. However, this effect was considerably reduced in fields larger than one hectare. The mixing of corn from the field borders with plants further away from the GM plantings - and which the heavy maize pollen did not reach even with strong winds - was responsible for this dilution effect.
The full article was published at the European Biotechnology Science & Industry News, 3(4), (2004), and can be downloaded at http://www.biocom.de/english/ebn-index.htm.