The United States department of agriculture has spent nearly US$13m buying genetically modified corn, to stop a protein that could cause allergies being eaten by humans. The protein Cry9C was developed by Aventis in its Starlink corn to repel the European corn-borer insect pest in animal feed. Last year it appeared in other crops, possibly due to pollen drift. Aventis is paying compensation to farmers whose crops have been affected.

By Kate Rew and Mike Fox, correspondents