Inventory of observed unexpected environmental effects of genetically modified crops

Based on a literature review and interviews, the researchers have mapped the effects of GM crops on the environment and agriculture, including the increase or decrease of insect populations and weeds on the field, change of cropping system, outcrossing of transgenes and emergence of resistance in insects or weeds.

The COGEM observes that, so far, cultivation of genetically modified (GM) maize, soybean, cotton, potato, oilseed rape and beet in North America have shown no major adverse unexpected agronomic and environmental impacts in the cultivation areas. Two unexpected adverse effects were observed with cultivation of herbicide tolerant maize. These indirect effects include a small decrease in the absorption of micro-nutrients and slightly increased disease susceptibility of herbicide tolerant plants. Both effects result from application of the herbicide glyphosate and are not caused by the transgenic trait itself.

The COGEM points out that mainly agronomic effects of GM cultivation in and around the cultivation area were mapped. Comprehensive monitoring of adverse environmental impacts associated with the cultivation of GM crops as is required in Europe, is missing in North America.