Gardening Columns

Genetically Modified Food

First published on garden.org on September 25, 2008, by Suzanne DeJohn

Next on your dinner plate: genetically modified salmon or pork. Last week the U.S. Food and Drug Administration (FDA) released draft "guidance" for producers of genetically engineered animals. The FDA will now begin accepting proposals to sell the animals as food. Just what does "genetically modified" mean? Let's start with plants, and the progression of breeding techniques that paved the way to last week's anouncement.

Creating New Varieties by Cross-Pollination
Humans have worked to produce better plants for millennia, looking to improve traits such as hardiness, taste, adaptability, and beauty. Plant breeding was once confined to good old-fashioned cross-pollination: The pollen of a flower from one plant was transferred to the stigma of a flower from another plant. If pollination was successful, the flowers produced viable seeds, and if the breeders were lucky, one of the plants that grew from those seeds had the beneficial traits they were seeking. The plants had to be compatible for pollination to occur; usually, that meant they had to be the same species. Manual cross-pollination is still an important technique and it's the main way amateur plant breeders create new varieties.

Mutations, Natural and Induced
Natural mutations can also create unique plants. Something causes a spontaneous disruption of the normal inheritance process -- perhaps a "mistake" in DNA replication -- and offspring display characteristics different from the parent plants. Observing how mutations can alter offspring, plant breeders began trying to induce mutations using irradiation and chemicals, hoping they'd eventually stumble upon mutations that resulted in beneficial changes. Scientists also developed "test-tube plants" using laboratory techniques to cross-breed plants that are incompatible in nature. But the plants still have to be at least somewhat compatible.

Genetically Modified Plants
Now leap ahead to genetically engineered plants, in which genes of completely unrelated species are introduced. The unrelated species don't even have to be plants! Perhaps the most well-known genetically modified (GM) crop is Bt corn. Scientists incorporated Bt (Bacillus thuringiensis, a bacteria that produces a substance toxic to caterpillars) into the DNA of corn plants. The result? Corn plants that resist corn earworm and corn borers, two major pests, meaning the crops require fewer pesticide applications.

Next up were GM soybeans altered with DNA from a soil bacteria that rendered the soybeans tolerant of Roundup herbicide. Farmers could use the spray to kill weeds without damaging crop plants. And just this year farmers began planting herbicide-tolerant GM sugar beets -- the plant that provides about half the country's refined sugar.

Developers of GM crops figured they were doing a good thing by reducing pesticide use and improving crop yields. But the public outcry against genetic engineering was swift and strong. Something just didn't sit right about mixing the genes of entirely different organisms. Consumers were wary of "Frankenfoods." Organic growers worried that the pests would develop resistance to Bt, an important organic insecticide. Environmentalists and farmers feared the creation of "superweeds" when pollen from herbicide-tolerant crops transferred to wild plants. And farmers who grew non-GM crops under organic certification or for export into countries that ban GM foods worried that genetic drift would evenually contaminate their non-GM plantings. Crazy ramblings borne of hysteria?

There are now more than a dozen weeds showing herbicide resistance and thus requiring stronger or more toxic herbicides. Canada learned the hard way that it's impossible to segregate GM and non-GM crops; no organic canola is now produced in Canada because all stock has been contaminated with GM varieties. And Bt-resistant bollworms were found in cotton fields in Mississippi and Arkansas within seven years of the introduction of Bt cotton.

Yet it appears GM crops are here to stay. According to one estimate, GM corn starch and soybean lecithin are now found in 70 percent of our processed food supply. According to the USDA, in 2006 about 61 percent of the corn, 83 percent of the cotton, and 89 percent of the soybeans planted in the United States were "biotech" varieties. Perhaps most relevant, according to one poll, only 24 percent of Americans polled believe they ever ingested any GM foods.

Up Next: GM Animals
With GM crops so widespread, could genetically engineered livestock be far behind? Right now, no GM animals are approved for commercial food production. However, last week's new guidelines could soon change that.

Rather than introducing specific new rules for GM food animals, the FDA is regulating GM animals under the "new animal drug" provisions of the Federal Food, Drug, and Cosmetic Act (FFDCA). In other words, the agency is treating the snippet of foreign genetic material being inserted into the animal's DNA the same as a medication. The FFDCA defines an animal drug as "an article (other than food) intended to affect the structure or any function of the body of animals." So, because that snippet of genetic material is intended to do just that, it meets the definition of a new animal drug.

Proponents say the approval of GM animals will open up a world of possibilities to improve our quality of life. Skeptics argue that the new guidelines don't go far enough in protecting the public. They argue that altering the genetic structure of an animal by inserting foreign DNA is much different than giving the animal a new medication, and therefore it warrants new regulations. And they feel that consumers should know if they're eating GM foods; the FDA won't require food from GM animals to be labeled as coming from GM animals, just as it doesn't require that food from GM plants be labeled as such.

Several categories of GM animals are being developed. One category includes food animals that grow faster or resist troublesome diseases, as well as those that contain levels of nutrients, such as omega-3 fatty acids, not normally found in that species. Another type is "biopharm" animals that will produce substances, such as insulin, for pharmaceutical use. A third is GM "xenotransplant" animals that will be factories for producing tissues or organs that can be transplanted into humans.

The first product likely to be evaluated under the new rule is a GM Atlantic salmon. Genetic material from an eel-like fish was inserted into the genes of the salmon, causing them to reach full size in about 18 months, instead of 30. Other evaluations are likely to include goats that produce insulin in their milk, pigs whose meat contains as much omega-3 fatty acids as fish, and cows that produce human antibodies.

FDA Invites Public Comment
What do you think? The FDA is inviting public comment on these new guidelines until November 18, 2008. Speak up at: http://www.fda.gov/cvm/GEAnimals.htm.