Student - October 4, 2007

GM crops less hard on environment

Farmers who grow transgenic crops use lower amounts of pesticides and therefore put less pressure on the environment, conclude RIKILT researchers and their international colleagues in a literature study soon to be published in Pest Management Science.

The total land area devoted to genetically modified crops is now twice the size of Spain. Most gm crops are more resistant to disease as a result of the modification they have undergone. Some manufacture their own insecticide through the implanted genes of the Bacillus thuringiensis soil bacteria, for example Bt cotton and Bt maize. Other crops can survive treatment with a broad-spectrum herbicide such as Round Up: weeds are killed but the crop survives as a result of genetic modification.

The International Union for Pure and Applied Chemistry, an organisation representing the chemical industry, started a project in 2002 in which researchers from nine countries examined the effect of the introduction of genetically modified crops on pesticide use. The leader of the recently completed project, Dr Gijs Kleter of RIKILT, is also first author of the study which will be published soon.

The publication indicates that in the United States – where companies and the government have collected more data than in other countries – farmers who grow herbicide-resistant soya, maize and cotton use 25 to 33 percent less pesticides than farmers who grow the same unmodified crops in their fields. Similar figures are also found in other countries. In Canada, for example, farmers growing herbicide-resistant rapeseed use 37 percent less pesticides.

Even taking into account the pesticides that gm crops manufacture themselves, Australian researchers calculated that a crop such as Bt cotton is less environmentally damaging than conventionally grown crops: 53 to 23 percent less than in conventional cotton.

In addition to environmental advantages, gm crops have more in their favour, say the researchers. Agricultural labourers and farmers come less into contact with pesticides and consumer exposure to pesticides is also less.

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