What Are Genetically Modified Organisms (GMOs)? Are They Safe?

By: Alia Hoyt
sun sets over a cornfield
The sun sets over a cornfield. Almost all the corn grown in the U.S. is genetically modified. David Papazian

People have been "genetically modifying" everything from food to dogs for centuries; but in the past, the only tool has been available was selective breeding. For example, if you wanted to create a breed of corn with resistance to a certain fungus, you would plant a plot of corn and see how individual plants did with the fungus. Then you would take seeds from the plants that did well, plant them, look at their performance against the fungus and so on over the years until you had created a strain of corn plant that had very high resistance to the fungus in question.

In the same way, you can take chickens, analyze their eggs and find chickens with eggs that contain less cholesterol. Then you breed them to create a strain of low-cholesterol chickens. You can select on any detectable trait and breed members of the species that do well on that trait. Using selective breeding techniques, people have created everything from variegated roses to giant pumpkins to strains of wheat with twice the yield and very high disease tolerance. But it often took years to get the desired traits.


Things went next level, however, with the advent of genetic engineering techniques, which allow scientists to insert specific genes into a plant or animal without having to go through the trial-and-error process of selective breeding. Genetic engineering is therefore extremely fast compared with selective breeding. With genetic engineering, you also can cross species very easily (for example, you can create a plant that produces human insulin). Any plant, microorganism, animal or other organism that has undergone genetic modification in a laboratory is considered a genetically modified organism (GMO).

To create a GMO, scientists must first figure out what the gene is that controls a particular trait, such as pest or virus resistance. Then, they copy the organism's genetic information for that trait and insert it into the DNA of the organism they want to grow (like corn or apples). Lastly, they grow the organism, which will ideally possess all the desired characteristics it has been manipulated for.

Why go to all the trouble? Genetic engineering is an exercise in efficiency, as it's used to improve crop harvests by outsmarting pests and plant viruses; decrease food-related waste by giving crops longer "shelf lives"; help make the food system more sustainable and improve production to meet the world's food supply demands. Genetic engineering also is designed to improve food safety and even enhance the nutritional value of foods.

For example, there is a widely used herbicide called Roundup, made by the company Monsanto. Roundup kills any plant that it touches. Monsanto has genetically modified soybeans and other crop plants to create "Roundup Ready" strains that are not affected by Roundup. By planting Roundup Ready seeds, a farmer can control weeds by spraying Roundup right over the crop. The crop completely ignores the herbicide, but the weeds are eliminated. Roundup Ready seeds reduce production costs and increase yield, so food becomes less expensive. (There have been a number of lawsuits filed against Monsanto alleging the plaintiffs got cancer from repeatedly using Roundup, reported Business Insider. But there is a lot of debate on that. The U.S. Environmental Protection Agency, the European Food Safety Authority and other national regulatory bodies say that glyphosate isn't linked to cancer to humans. Meanwhile, the World Health Organization says the chemical is "probably" carcinogenic.)

Other scientists have inserted genes that produce a natural insecticide into corn plants to eliminate damage from corn borers, and a variety of anti-fungal genes can be inserted as well. Genetically modified apples were even created that resist browning, which ideally reduces food waste because many people assume browned apples are spoiled.

For many years, U.S. consumers were unaware of the creation of foods using GMOs, although they have been available since the early 1990s. By 2018, 94 percent of soybean and 92 percent of corn grown in the U.S. was from GMOs, according to the Food and Drug Administration. Despite stringent government regulations and more than 2,000 scientific studies proclaiming the safety of GMOs, a lot of people are none too pleased. A common complaint is that consumers don't trust the ingredients used in the genetic modification process, as they are not considered "natural." Plus, since most farm animals eat GMO corn, does that have ill effects for them and for people who eat meat?

There has also been quite a fight over whether or not products containing GMOs should be labeled as such. One side says that since multiple studies have shown them to be as safe as their non-GMO counterparts (possibly more so), any labeling efforts would be a waste of time and money. The other side considers them to be unsafe and says consumers should know exactly what they're eating. To that end, the National Bioengineered Food Disclosure Standard was signed into law in 2016, requiring labels on bioengineered foods (for human consumption) that contain more than 5 percent genetically modified material. Implementation dates range from 2020 to 2022, depending on the type of food and the size of the manufacturer (smaller groups have longer to put labels in place).

People will be able to quickly ascertain whether a food contains GMOs thanks to a label that says either "bioengineered" or "derived from bioengineering." Some types of food intended for human consumption are exempt from this labeling rule, including food served in restaurants, delis, food trucks, airplanes, trains and the like. Very small food manufacturers don't have to comply.