19 April 2002

'Worst ever' GM crop invasion

By Charles Clover, Environment Editor in The Hague

The world's worst case of pollution by genetically-engineered crops has taken place in southern Mexico, the gene bank for maize, one of the world's staple crops, the Mexican government said yesterday.

Findings by Mexican scientists mark a new twist to a story that has provoked a bitter scientific battle on both sides of the Atlantic.

Earlier this month Nature, Britain's leading scientific journal, took the extraordinary step of disowning a paper it published in November by David Quist and Ignacio Chapela, researchers at the University of California, Berkeley, claiming to prove that genes from GM maize grown in the United States had accidentally crossed into Mexico.

At the time Dr Quist said his research showed the benefits of GM crops "don't outweigh the enormous risks to food security".

The paper sparked a protest to Nature by 100 leading biologists. It was also disowned by the Mexican government after their scientists could not repeat the experiment.

Latest tests were carried out by Mexican government scientists in an attempt to settle the controversy, Jorge Soberon, head of the Mexican delegation, told a meeting of parties to the Convention on Biological Diversity in The Hague.

Some 1,876 seedlings from indigenous varieties of maize grown by traditional farmers in the rural southern states of Oaxaca and Puebla were analysed by scientists from the National Autonomous University of Mexico and the Environment Ministry.

In 95 per cent of the sites surveyed, they found traces of a gene from the cauliflower mosaic virus, used as a promoter to "switch on" insecticidal or herbicidal properties in GM varieties of maize used in the United States.

Contamination varied from one to 35 per cent of a farmer's crop, with 10-15 per cent average, showing that GM genes had cross-pollinated at a speed never before predicted in the four years since GM maize entered the country.

Mr Soberon, secretary of the environment ministry's national commission on biodiversity, said: "This is the world's worst case of contamination by genetically modified material because it happened in the place of origin of a major crop. It is confirmed. There is no doubt about it."

Philip Campbell, editor of Nature, said: "The Chapela results remain to be confirmed. If the Mexican government has confirmed them, so be it."