Study: GM crops pose few ecological risks

February 7, 2001

From Alex Walker
CNN Science Producer

SILWOOD PARK, Britain (CNN) -- Genetically modified crops are not likely to harm natural habitats or persist in the wild longer than their conventional counterparts, according to a long-term study published in the journal Nature.

Scientists at Imperial College in Britain monitored four crops at 12 sites over a period of 10 years to test whether the plants would become "superweeds" of agriculture or invasive of natural habitats. The study also looked at whether weedy or invasive hybrid offspring would result from cross-pollination with wild relatives.

"We tested all of the genetically modified crops available in 1990," said Michael J. Crawley, primary author of the study. "In no case was the GM crop more invasive than its conventional counterpart. The risks with these crops and these constructs truly are negligible."

The genetically modified, or GM, crops studied were oilseed-rape, maize and sugar beet plants tolerant of herbicides, and potatoes with either insecticidal Bt toxin or pea lectin.

Also known as transgenic crops, the plants contain a gene or genes that have been artificially inserted instead of being acquiring through pollination. Transgenic Bt potato, for example, contains a gene from a bacterium.

"I was not surprised by the findings," Crawley told CNN. "Competition with other plants is the main force affecting plants in the wild.

"There was no reason to expect the GM for herbicide tolerance would increase competitive ability, except of course if that particular herbicide was applied. But that would not happen in natural habitats."

The British government and a worldwide consortium of biotech companies, including Monsanto Co. and Zeneca Ag Products Inc., funded the study. In addition, the GM seeds used were provided by the corporate sponsors.

The study did not assess whether GM plants might be a direct hazard to humans or to domestic livestock by being toxic or allergenic.

Some scientists and political activists have urged extreme caution in creating and marketing genetically modified foods, warning that still-unknown health and environmental risks could be unleashed by tampering with the building blocks of life.

Widespread protests, particularly in Europe, have opposed the growing of any GM crops.