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Sustainable Food Guide
Environmental Practice at Work © 2005 Link:EP@W Ltd Web Site


 GM & Environment...

The Advisory Committee on Releases to the Environment (ACRE) approves GM crops by assessing both direct and indirect impacts on the environment (cf Pesticides Approval).

Biodiversity. Farm Scale Evaluations (FSE) in 2003 measured the effects of three GMHT (GM Herbicide Tolerant) crops on biodiversity. The FSEs showed that the GMHT rape and beet crops had "adverse effects on arable weed populations". In contrast, GMHT maize, grown and managed as in the FSEs, would not result in adverse effects. However,the herbicide used in this management regime was atrazine - now banned in Europe.

Cross Pollination. Cross pollination of GM crops with conventional crops is inevitable. Bees fly 10 kilometers cross pollinating as they go. Pollination by wind can be as far as 250 kilometers. Spills and seed transfer from tractors, harvesters and merchants add another dimension to distribution. The GM genes are usually 'dominant' genes - in order to impress the desired characters. Cross contamination is inevitable.

Resistance. There are examples of genes built into some crops to provide resistance to weedkillers that have jumped into weeds - thus giving them the same resistance. For latest list of herbicide resistant weeds. For latest UK research, "search" the Biotechonology and Biologocal Science Council.

There is also insect resistance. Insect resistance genes in GM crops may cause adverse effects on non-target insects. Predators or parasitoids which feed on the pest may be affected indirectly when feeding on prey or hosts which contain the toxin after feeding on the GM plant.

Pesticides Do GM crops reduce pesticide use? They do and they don't. In November 2003 a US study of overall levels of pesticide use on GM corn (ie maize), soybeans and cotton reports that the GM varieties have risen.

  • Use of Bacillus thuringiensis (Bt) transgenic varieties reduced pesticide use by an estimated 19.6 million pounds in the past eight years,
  • Herbicide tolerant crops have been responsible for the application of an estimated 70 million additional pounds of pesticides.
graphic: maize

Practical experience from the USA shows that GM crops require more pesticides than their convential counterparts, according to the chair of the Small & Family Farms Alliance. Overall, GM crops have caused 50 million additional pounds of pesticides to be used in U.S. agriculture. More

Contamination. According to (ACRE), toxins in the 'bt maize' pollen (corn with built-in insecticides) may harm the larvae of Monarch Butterflies on nearby plants. How many insects does it take to accept the risk is too high?


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