Early environmental fears about potential negative effects of Bt corn pollen on monarch butterflies, or of Bt toxins on soil organisms, have not materialized in repeated studies. "We've seen no uptake of Bt toxins by other plants or any effect on soil microbes," says Guenther Stotzky, a soil microbiologist at New York University. "That's why Im no longer a critic of Bt crops."
A Risky Escape
BUT AT LEAST one environmental risk looms: escape. Researchers have long worried that unwitting insects or the right wind could carry GM crop pollen to weedy plant relatives, fertilizing them. The newly endowed plants could then break ecological rank, becoming "superweeds" that push out native plants or resist pesticides.
Until recently, that fear remained fiction, as scientists engineered farm crops that mostly lack wild, weedy relatives in the U.S. But in August 2006 ecologists at the EPA reported the first wild outbreak of a GM crop: a turfgrass.
In central Oregon the Scotts Miracle-Gro Company had field-tested an herbicide-tolerant variety of creeping bentgrass, for possible use on golf courses. Surveying the nearby area, EPA scientists found wild grass with the genetic modification at six sites, some more than two miles away from the test plots.
Reporting in the journal Molecular Ecology, the scientists suggested that wind carried the modified grass's seeds and pollen to the locations where new plants emerged. The USDA has launched an environmental impact assessment of the transgenic grass to determine whether it could spread and become invasive.
The runaway grass alarms scientists, in part because they worry that next-generation GM crops--such as "biopharms," or plants engineered to yield pharmaceuticals--could similarly escape. "When we start growing antigens that could get back into the food chain, this kind of event becomes much more serious," Stotzky says.
Already the USDA has come under fire for its oversight of biopharming. Four environmental groups have successfully sued the agency over biopharm field trials in Hawaii, in which corn and sugar cane plants were modified to make human hormones and vaccine ingredients to fight HIV and hepatitis B. In August a U.S. District Court judge in Hawaii ruled that the USDA broke national environmental laws by allowing the open-air field trials without first considering their environmental impact, particularly on endangered species. In response, the USDA has overhauled its permit process.
Beyond the field, experimental GM crops have repeatedly found their way into the food supply--twice during the summer of 2006 alone. First, Riceland Foods, the country's largest marketer of rice, discovered trace amounts of an unapproved herbicide-tolerant rice strain in its commercial rice supplies, which are grown across a wide region of the southern U.S. In response, the European Union placed strict testing requirements on U.S. imports, sending U.S. rice prices tumbling and provoking a class-action lawsuit by farmers alleging that Bayer CropScience--which had bred the rice--was negligent in preventing GM seeds from contaminating the nation's seed supply.
Also last summer, the environmental groups Greenpeace and Friends of the Earth reported that their tests of processed rice foods in London had turned up five samples of rice products imported from China, such as vermicelli and rice sticks, containing an unapproved insect-resistant rice variety. The European Commission urged member states to step up controls of GM foods, which are not approved for consumption in Europe.
But that will be difficult to do, Ellstrand says. In an ongoing 1.5-million study funded by the National Science Foundation, he leads a team of biologists and social scientists collaborating to analyze the unintended spread of engineered plant genes. One serious problem is the frequent disconnect between policymakers, seed salespeople, regulators and farmers about how to grow and control GM crops," Ellstrand explains. As seeds and food cross borders, he adds, that coordination dissolves further.