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From The May 2000 Issue of Nutrition Science News
Features
GMOs: Down on the Pharm
by Todd Runestad
 You don't have to speak "European" to understand GMOs anymore. People in America, home of the brave and land of the genetically modified organism, are finally realizing that the food chain is being engineered by scientists, with much promise—and peril.
Scientists create genetically modified organisms (GMOs) by first identifying a gene with a desired characteristic from a plant, animal or bacterium. The gene is isolated and removed. Next, it is inserted into a bacterial cell that copies it millions of times over and ferries it into a target organism. Genes can also be directly injected into a target organism, without being multiplied, by electroporation (using electric shock) or by using a particle gun. From there, it is up to nature to weave the protein string into a new strand of deoxyribonucleic acid (DNA). For instance, the gene for a protein that keeps the arctic flounder from freezing has been inserted into tomatoes and strawberries to keep the produce from dying during a frost.
Touted as a way to feed the world with more nutritious foods, only 19 percent of current GM foods are actually designed to improve product quality, according to the U.S. Department of Agriculture (USDA). The rest make cultivation and distribution easier, with 28 percent aimed at increasing crop tolerance to herbicides.
Even so, returns to farmers are a mixed bag. Technology fees for biotech seeds cost anywhere from $8.50 to $30 an acre, so what farmers save on chemical costs are often negated by high-tech seed fees. Both USDA and university studies concur that farmers tend to realize economic gains with pest-resistant GMOs only in fields heavily infested with insects.1,2
Four Red Flags
The hue and cry against GMOs is mostly a matter of risks vs. returns. Biotech backers say the USDA and U.S. Food and Drug Administration (FDA) adequately test and sign off on new GM products. Opponents disagree and note that biotech potatoes used to make fast-food french fries are registered with the U.S. Environmental Protection Agency (EPA) as pesticides, not foods, and are thus not under FDA jurisdiction. GMO studies indicate four known risks.
Insect Resistance Bacillus thuringiensis, or Bt, is a natural soil bacterium long used to thwart caterpillars and other pests that thrive on corn, potatoes and other crops. Organic growers are able to use Bt to effectively control insect infestations. When sprayed on crops, Bt dissipates in a few days. To fight the European corn borer, which causes U.S. farmers an estimated $1.2 billion in annual crop losses, biotech companies slip Bt into corn so that every cell in every part of the plant always exudes this insect toxin. One study by researchers at New York University found that Bt engineered into crops leached from roots and remained in the soil for at least eight months (the duration of the experiment).3 Because of the ubiquitous nature of Bt in the GM corn, researchers predict insects will develop immunity to Bt within five years—leaving organic farmers without one of their few safe, natural pest-management tools. Because of this concern, EPA now requires farmers to provide 20 to 40 percent of their acreage as a non-Bt corn refuge, though compliance has reportedly been spotty.4
Animal Damage There are other problems with genetically engineered Bt products. In what has been called the smoking gun against the biotech industry, a now-famous laboratory study by Cornell University researchers found pollen from Bt corn kills monarch butterfly larvae. Researchers fed monarch caterpillars milkweed leaves, their only natural food source, which had been dusted with either Bt corn pollen, regular corn pollen or no pollen. After four days, 44 percent of those fed Bt corn pollen died, while all those fed the other milkweed leaves survived. In addition, the caterpillars on Bt pollen-dusted leaves consumed half as much as the caterpillars eating the regular corn pollen and one-third the amount as those eating pollenless leaves. This cut their growth rates in half.5 The study was even more significant because 50 percent of the summer monarch population is concentrated in the U.S. corn belt.6 In response, a consortium of government- and biotech-backed scientists in November 1999 released six months of field studies that found, for the most part, little risk to monarchs.7
In a laboratory study, Swiss researchers fed Bt corn to the larvae of green lacewings, a beneficial bug that eats crop-eating insects. Fifty-seven percent of green lacewings died, compared with 30 percent in the untreated control group, a significant difference.8
In another twist, researchers at the Rowett Research Institute in England fed six rats potatoes genetically engineered to make their own lectins, a group of chemicals that includes poisons found in some bean varieties. Six other rats were fed potatoes injected with the protein. After 10 days, the rats eating the engineered potatoes suffered greater atrophy in the small intestine and other organs than those eating the potatoes spiked with lectins. The researchers said this suggests something in the modification process may contribute to organ damage.9
Food Quality Since 1992, FDA has required allergy tests for all altered foods made with genes taken from eggs, fish, legumes, milk, nuts, shellfish and wheat—foods that account for most food allergies in the United States. In 1996, researchers at the University of Nebraska, Lincoln, assessed whether a soybean modified with a nutritious protein from a Brazil nut (Betholletia excelsa) would cause allergies in people allergic to Brazil nuts, a potential danger because people with allergies to nuts would not think to avoid soy. Eleven of 15 subjects had positive reactions to the soybeans, indicating that genetic engineering can transfer allergens.10
Also, researchers at the Center of Ethics and Toxics in Gualala, Calif., and at Children's Hospital Medical Center in Cincinnati, Ohio, found GM soy to have lower phytoestrogen levels than normal soy. Two varieties of GM soy were compared to their conventional counterparts grown in similar conditions. In 12 of 21 analyses, the GM soy demonstrated a 12 to 14 percent reduction in genistein and daidzein, the two major soy isoflavones of benefit to menopausal women.11
Genetic Pollution Unlike chemicals or even nuclear waste, once GM plants cross-pollinate with their wild counterparts and weeds, there is no way to put the genie back in the bottle. Pollen dispersal has been recorded at up to 3 km by air flow and 4 km by insects.12 The threat to organic farmers with nearby fields is manifest, as evidenced by an early 1999 organic corn chip export to Europe that was tested and found to contain genetically modified corn, a result of wayward pollen.
Who's fault does genetic pollution become? Some biotech advocates say the onus is on organic farmers to keep GM pollen out. The Spanish government, meanwhile, has decided that companies producing or planting GMOs must contribute to a $100 million insurance fund intended to cover environmental accidents—not that money will reverse the problem.
Engineering Compromise
A recent about-face in the GMO debate was the development and subsequent market withdrawal of so-called terminator seeds, which are engineered to be sterile after the growing season, ostensibly to make growers continue to purchase seeds from the biotech firms. Although shelved, two British geneticists noted that such technology could offer an important mechanism for environmental containment. "By genetically modifying sterility," says Andrew Jackson, researcher at the University of Leeds, "one could ensure that GM plants could not spread or cross-pollinate with naturally occurring varieties."13 They call the threat of sterile GM pollen causing widespread sterility "biologically implausible."
Where consumers have resisted GMOs, particularly in Europe, the second wave of GM foods may well succeed where the first generation did not—through consumer benefit via improved nutrition. At the top of this second wave is a new GM rice that contains beta-carotene, an important nutrient in developing countries. UNICEF says 300,000 children in developing countries were saved in 1998 by vitamin A supplementation. The grain was developed by the Swiss government and the New York-based Rockefeller Foundation, which are giving away the "golden rice" to growers in developing countries.
With so much bluster accompanying the GMO debate, some perspective may be in order. Mark Tester, a researcher in the department of plant sciences at Cambridge University in England, suggests three GMO classifications would clarify some of the confusion. Tesler cites the relatively benign "tweaking" of levels or patterns of gene expression already present in a plant's genome as the first classification level. An example is altering a tomato so it contains higher lycopene levels. The second type of engineering is "close transfer," referring to movements of genes between plant species, such as transferring a characteristic of tobacco to cotton to increase insect resistance. The third is "wide transfer," the movement of genes from organisms of other kingdoms into plants, such as transferring genes from the Bt toxin to corn for insect resistance. While wide transfers should be the focus of intensive testing, as required for the introduction of a drug, tweaking a plant probably poses little risk, says Tesler.14
Clearly, a science-based risk assessment of GMOs should take into account its own data and not ignore them. Enough questions are now being raised—some say 50 million acres too late—that may jeopardize the future of genetically engineered foods, whether they are indeed beneficial or not.
Todd Runestad is associate editor of Nutrition Science News.
References
1. Minor HC, et al. Corn: 1999 Missouri crop performance. University of Missouri-Columbia Special Report 521, 1999 Oct.
2. USDA Economic Research Service. Conference on transitions in agbiotech: economics of strategy and policy. Washington, D.C. 1998 Jun 24. www.econ.ag.gov/whatsnew/ issues/biotech/index/htm.
3. Saxena D, et al. Insecticidal toxin in root exudates from Bt corn. Nature 1999 Dec 2;402:480.
4. Pollan M. Playing God in the garden. NY Times 1998 Oct 25. Section 6:44.
5. Losey J, et al. Transgenic pollen harms monarch larvae. Nature 1999 May 20;399:214.
6. Wassenaar LI, Hobson KA. Natal origins of migratory monarch butterflies at wintering colonies in Mexico: new isotropic evidence. Proc Natl Acad Sci USA 1998;95:15436-9.
7. Niiler E, et al. GM corn poses little threat to monarch. Nat Biotechnol 1999 Dec;17(12):1154.
8. Hilbeck A, et al. Toxicity of Bacillus thuringiensis CryIAb toxin to the predator Chrysoperla carnea (Neuroptera: chrysopidae). J Environ Entomology 1998 Aug;27(4):480-7.
9. Ewen SW, Pusztai A. Effect of diets containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine. Lancet 1999 Oct 16;354(9187);1353-4.
10. Nordlee JA, et al. Identification of a Brazil-nut allergen in transgenic soybeans. N Engl J Med 1996 Mar 14;334 (11):688-92.
11. Lappe M, et al. Alterations in clinically important phytoestrogens in genetically modified, herbicide-tolerant soybeans. J Med Food 1998;1(4):241-5.
12. Treu R, Emberlin J. Pollen dispersal in the crops maize, oil seed rape, potatoes, sugar beet and wheat. Soil Association report, 2000 Jan.
13. Jackson A, Inglehearn C. This should not be the end for terminator technology in GM crops. Nature 1999 Dec 2;402:457.
14. Tester M. Seeking clarity in the debate over the safety of GM foods. Nature 1999 Dec 9;402:575.
Photo Illustration: © Nancy McLaughlin
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