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Seeds of Concern [Preview]

Are genetically modified crops an environmental dream come true or a disaster in the making? Scientists are looking for answers

How is your genetically modified diet going? If you ate cereal, drank soda, munched baked snacks or used cooking oil this week, you very likely ate some engineered protein--now a staple of American fare.

During the past decade the amount of farmland devoted to genetically modified (GM) crops has increased more than 50-fold, to an estimated 222 million acres worldwide in 2005, according to the International Service for the Acquisition of Agri-Biotech Applications (ISAAA). The U.S. grows more than half this biotech harvest, followed by 20 additional countries. Today's top crops: soybeans, corn, cotton, and canola modified to tolerate specific herbicides or resist certain insects. Tomorrow new GM crops might withstand drought, resist viruses, grow bigger, yield pharmaceuticals and do other things nature never imagined.

But it is not all sunshine and sweet profit for GM farming. Controversy--and confusion--over the technology remains. "We havent had the asparagus that ate Cleveland," says geneticist Norman Ellstrand, director of the Biotechnology Impacts Center at the University of California, Riverside. "But there's been at least one notable event of engineered crop genes escaping from farms or field trials every year--and that doesnt give us comfort."

And GM crops suffer other growing pains. Their measurable benefit--in reduced pesticide use or increased yield--varies considerably, depending on the technology, crop and region. Moreover, preliminary research indicates that at least one kind of GM cotton is losing ground against pests. Finally, public debate over GM foods continues, pitting state and local legislatures--and sometimes entire countries--against each other. As Jane Rissler, deputy director of the food and environment program at the Union of Concerned Scientists, puts it: "From where I sit, genetically modified crops are not a slam dunk."

A Modified Farmscape
IT ALL BEGAN with business. Although relatively small compared with other agricultural product markets, the commercial seed market in the U.S. (about $5.7 billion) and worldwide (about $25 billion) is rapidly growing, particularly for major field crops, according to the U.S. Department of Agriculture. Fewer than half a dozen companies dominate the domestic seed market, and as biotechnology emerged, they saw an opportunity to genetically modify crop seeds with one or more desirable traits. Many farmers were willing to pay for premium seeds with these traits.

Today most GM crops contain genes enabling them to either resist insect pests or tolerate weed-killing herbicides [see box on page 44]. The herbicide-tolerant types contain genes enabling them to survive when exposed to broad-spectrum weed killers such as glyphosate (sold as Round-up), potentially allowing farmers to forgo more toxic chemicals that target specific weed species. The insect-resistant varieties of GM crops make their own insecticide, a property meant to reduce the need for chemical sprays. To date, insect resistance has been provided by a gene from the soil bacterium Bacillus thuringiensis (Bt). This gene directs cells to manufacture a crystalline protein that is toxic to certain insects--especially caterpillars and beetles that gnaw on crops--but does not harm other organisms.

In 2005 herbicide-tolerant varieties represented 87 percent of the U.S. soybean crop and 61 percent of the cotton crop. That same year Bt varieties represented 35 percent of the U.S. corn crop.

"These crops have shown clear benefit," says Zigfridas Vaituzis, a senior scientist at the Environmental Protection Agency. "With herbicide-tolerant crops, farmers can spray their fields with relatively safe, biodegradable chemicals," Vaituzis says. "For its part, Bt cotton has cut pesticide use on cotton crops by half. A conventional cotton crop may take 12 applications of various pesticides each season. Halving that means less exposure to those chemicals, both on the farm, in groundwater and in spray drift in the surrounding community. Those are measurable benefits."

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