(Editor’s note: This is the second in a two-part series about genetically engineered foods.)
By Patricia Bailey
Even if the new genetic engineering technologies can’t be dismissed on the grounds they’re unnatural, some critics fear genetic modification will cause irreversible damage to the environment.
"There are thoughtful people who would like to know about the potential environmental risks of genetically modified crops," said Ford Denison, an agronomy professor and director of the campus’s 100-year Long Term Research on Agricultural Systems project. He is primarily concerned about the evolutionary impact of genetically modified crops on insect and weed populations.
"It may be possible to minimize these risks but until UC Davis hires at least one faculty ecologist or evolutionary biologist to work on this problem, we won’t be part of the solution," Denison said.
Bt corn, for example, is genetically modified to produce a bacterial toxin, Bacillus thuringiensis, that has been used for years as a natural insecticide. Because it is naturally occurring, rather than chemically synthesized, Bt has been an important pest-control tool for organic farmers and gardeners.
The new genetically modified Bt corn targets the corn borer, a major pest for Midwest corn growers. The pest-resistant corn gained approval from the federal Environmental Protection Agency and the U.S. Department of Agriculture, but a subsequent study by a Cornell University researcher last year suggested that the pollen of Bt corn might endanger monarch butterfly populations.
Study merits debated
Scientists have been debating the merits of the study since it was published in the journal Nature in May 1999. Some argue that the laboratory study did not accurately reflect field conditions. They note that monarchs migrate through the corn-growing regions before pollen is produced on the corn and they feed strictly on milkweed, which seldom grows in cornfields.
Other researchers point out that the EPA does routinely consider possible effects of genetically modified Bt crops on both targeted pests and non-target insects, requiring growers of crops that have been modified to contain Bt or other pesticidal proteins to establish nearby refuge areas for susceptible insects.
"Still, we need to pay attention to research like the monarch butterfly study," said Denison. In some cases, Bt corn might be a substitute for insecticide sprays, but Denison suggests that this environmental benefit may not last long. He worries that widespread use of Bt-producing crops might cause pest populations to more quickly evolve a resistance to the natural toxin, robbing organic farmers of one of their few tools for insect control.
Transferring genes into the wild
Transfer of introduced genes into the wild is one of the major environmental concerns associated with genetically modified crops. For example, consider a weed that picks up the ability to resist herbicides from a genetically engineered crop.
Cotton, soybean, corn and canola plants have been genetically modified to tolerate the herbicide Roundup. The new plants allow farmers to spray their fields with Roundup, killing the weeds but not harming the crop. But if that herbicide-resistance gene were to get into wild plants, would they grow uncontrollably, no longer fazed by chemical herbicides?
"Transfer of herbicide-tolerance genes to weedy species is something we should be concerned about," said George Bruening, director of the Center for Engineering Plants for Resistance Against Pathogens.
Human health risks
In addition to potential environmental risks, critics of genetic modification also question how food products made from genetically altered crops will affect human health. One of their greatest concerns is that a plant will be genetically engineered to produce a protein to which some people are allergic.
In 1995 Pioneer Hi-Bred, a large agricultural seed company, discovered that a Brazil nut protein that had been inserted into a soybean plant to produce a more nutritional cattle feed was one of the major causes of Brazil-nut allergies in humans. Realizing there was no guarantee the modified soybean could be kept out of the human food supply, Pioneer immediately dropped all plans to commercialize the modified soybean. But that incident lives on in the minds of some critics as an example of the potential danger of genetic engineering. Proponents of genetic engineering, on the other hand, cite the Brazil-nut case as an example of how well the system works in catching problems in the modified crops.
"The public wants to hear that genetic modification is risk-free," said Martina McGloughlin, UC Davis Biotechnology Program director. She is confident that the U.S. Food and Drug Administration, which checks proposed genetically modified food products for potential allergens, will safeguard public health.
"And the companies look at these issues every step of the way," noted McGloughlin. "It’s not good business to poison your customers."
Economic and social issues
Genetic modification also raises new questions about economic and social equity. What if genetic modification techniques further concentrate control of the world’s food supply in the hands of a few agribusiness corporations?
"I agree with critics who argue that the first genetically engineered products brought to market were not of significant benefit to the public," said plant physiologist Alan Bennett. "We have seen that most of the applications have been designed to meet primarily corporate goals. Industry has a responsibility to, if not directly promote, at least make the technology available to places where it will have an impact on feeding people."
Other researchers disagree, noting that the steps taken to reduce pesticide use through Bt-containing crops and Roundup-resistant crops have already produced significant environmental benefits.
In January, an international team of scientists took a major step toward improving the health of people in developing nations through genetic engineering, announcing that they had successfully boosted the vitamin A content of rice by inserting genes from bacteria and daffodils. The new rice could go a long way toward correcting a dietary deficiency that kills or blinds millions of children around the world each year.
"Feeding the world is not simply an excuse to justify genetic modification; it’s a very real need," Bennett said.
The controversy on campus
With last fall’s crop destruction on campus, the genetic engineering controversy touched home. However, neither faculty members nor their students have been dissuaded from pursuing genetic engineering studies, says Bennett.
Biotechnology continues to be the fastest growing major in the College of Agricultural and Environmental Sciences, with enrollment climbing by 300 students during the past three years.
"We are not going to pull back from research on genetic modification," said Neal Van Alfen, dean of the college. "People recoil from the future and tend to want to go back to the way things were. But with the existing levels of global poverty and population growth, we can’t not do genetic engineering."
Public education
Ultimately, the future of genetic engineering lies in the hands of consumers. Without a market for the food and fiber produced by genetically modified crops, the industry would wither.
"The university needs to take more of a leading role in public education," said geneticist Thea Wilkins of agronomy and range science, who is directing a $3.8 million federally funded project aimed at identifying all of the genes in cotton with hopes of eventually improving the quality of cotton fibers. Since last fall’s crop destruction on campus, she has fielded numerous phone calls from community members with questions about genetic modification.
"Clearly, this is a case where researchers need to interact more with the public," she said. "We need to listen to their concerns and respond in kind."
This story originally appeared in the spring issue of UC Davis Magazine.