Genetically Engineered Food: Promises & Perils

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Relying on chemical sprays to manage pests, weeds and diseases is a silver-bullet approach that creates a pesticide treadmill. Drawing on 50 years of toxic chemical use to control cotton pests, Benbrook says every family of chemicals had about a decade before their targeted pests became immune. "There is no reason to expect that resistance will take much longer to emerge in regions where Bt crops are planted extensively," he wrote in die October 2001 issue of Pesticide Outlook. He also predicts increases in herbicide use, especially with the popular Roundup-ready crops, as weeds develop resistance to the chemicals.

Before transgenic crops were released, environmentalists warned about the creation of "superweeds" and "superbugs" that would be more difficult to control than current pests. Scientists have now documented canola plants in Alberta. Canada, that became resistant to three different herbicides after the plants incorporated pollen from three corresponding herbicide-tolerant transgenic varieties growing nearby. The spread of canola with herbicide-resistant genes has become quite a problem in Canada, forcing farmers to use older and more toxic weed killers, such as 2,4-D, to get rid of it.

The Consumer Policy Institute's Michael Hansen says as more bioengineered crops that have wild relatives are grown—for example oats, sugar beets or sorghum—superweeds may become more of a problem. As for superbugs—agricultural pests or bacteria that have become immune to pesticides or antibiotics from overuse—he says inadequate effort has been made to detect them. "People think the regulatory agencies are gathering all this data, but as a recent National Academy of Sciences report pointed out, the sample sizes for most studies assessing the bio logical impact of transgenic crops are typically so small that they couldn't show any impacts," Hansen says.

Last fall's announcement of the transgenic contamination of native corn plants in Oaxaca, Mexico, an ancestral home land for corn, also has raised alarms about how fast GMOs can spread. Crop homelands need to be preserved, because that's where scientists go to look for traits to over come catastrophic pests or diseases, as was necessary in 1970 when the Southern corn leaf blight wiped out 15 percent of the U.S. corn harvest. The GMO contamination occurred despite Mexico's 1998 ban on planting transgenic corn and may have resulted from seeds that sprouted after falling off government trucks, which brought bioengineered corn into Oaxaca as food aid.

Concerns about wandering transgenic traits are taking on new urgency with the development of gene-spliced pharmaceutical and industrial plants. According to the USDA's Animal and Plant Health Inspection Services (APHIS), the primary government agency regulating field trials of bioengineered plants, 30 sites are now testing GM crops in the environment. The identity of the compounds is considered "confidential business information" and cannot be released. But there are reports that some of the substances already growing in GM-plant field tests include antibiotics, vaccines, plastics, fuels and solvents.

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