What are GMOs?

Industrial agriculture's most controversial tool raises concerns over pesticide use and corporate control, but some believe the technology could help feed the world.

(Photo: Pete Turner/Getty Images)

When most people mention GMOs, they are specifically referring to genetically modified foods ("genetically engineered" or "G.E." are also used interchangeably) that have been manipulated to carry new or modified genes that control characteristics such as pesticide/herbicide resistance, disease resistance, ripening, and nutrient content.

How are GMOs made?

Scientists discovered that they could transfer DNA between two organisms in 1946, and the first genetically engineered plant—an antibiotic-resistant tobacco plant—was developed in 1983. One of the first food-related GMOs was the Flavr Savr tomato. California-based Calgene produced it from tomato seeds genetically modified to contain the ACC synthase gene, which delays ripening until after picking. The Food and Drug Administration approved Flavr Savr for sale in the United States in 1994, and although it was never a commercial success, it helped lead to the approval of a slate of genetically modified food crops in 1995: canolaBacillus thuringiensis (Bt) corn and potatoes (which produce their own pesticide), soybeans resistant to the herbicide glyphosate, virus-resistant squash, and additional delayed-ripening tomatoes. (Neither the potatoes nor the tomatoes are now commercially produced.) In 2000, scientists genetically modified rice to increase its vitamin A content, marking the first time the technology was used to increase food’s nutrient content.

Today, roughly 85 percent of corn, 91 percent of soybeans, and 88 percent of cotton grown in the U.S. are genetically modified. Other common GMO foods include canola, sugar beets, Hawaiian papaya, and alfalfa. The FDA is in the process of approving the first G.E. fish—the AquaAdvantage salmon—which was engineered to be faster growing, disease resistant, and more temperature tolerant and to develop larger muscles.

What's up with GMO labeling?

Groups skeptical of biotechnology have pushed for state-level laws mandating that GMO foods be labeled. Their rallying cry is that citizens have the right to know whether their food has been modified. Sixty-four countries require G.E. foods to be labeled; the U.S. and Canada do not. Three U.S. states—Connecticut, Maine, and Vermont—have passed labeling laws, but only Vermont's will go into effect on its own; the other states require that a coalition of regional government pass similar laws before labeling will be required. In 2014, thirty-five labeling bills have been introduced in 20 states, and residents in Oregon and Colorado will vote on such measures in November.

Foods that are certified organic cannot have been genetically modified, and the Non-GMO Project has independently verified more than 20,000 products. 

What's the GMO debate about?

G.E. food’s critics oppose the practice of manipulating our food system for several reasons. They say the FDA doesn’t require the same safety studies of G.E. food that it does of new drugs, resulting in few reports from independent scientists on the effects of genetically engineered foods. Critics also say the proliferation of genetically modified herbicide-resistant crops has led to the mutation of “superweeds” and insects that are impervious to herbicides and pesticides. This has led to an increase in the use of pesticides and herbicides since G.E. crops were introduced in American agriculture. Some farmers who grow and sell organic produce have experienced cross-contamination from G.E. fields, leaving them unable to sell in countries that have strict bans on the sale of G.E. food or require modified foods to be labeled. 

Finally, many oppose GMOs on the ground that a few powerful companies—including Monsanto, Dow, and Syngenta—control both the genetic modification of seeds and the production of the pesticides and herbicides these crops are designed to withstand. Genetic modification has even led to the patenting of certain seeds, and Monsanto has sued farmers for saving and replanting seeds the company “owns.”

Proponents of genetically modified foods say they’re completely safe for human consumption and that no negative effect associated with their use has been found. They also say the cultivation of G.E. foods is necessary for increasing crop yields around the world. Some notable voices, including Bill Gates, have praised genetic modification for its potential to dramatically cut back world hunger. They also point to the relatively long time Americans have been eating genetically modified foods, adding that the phenomenon has made food cheaper for consumers.

What are the benefits of GMOs?

The Hawaiian papaya industry was all but doomed before a genetically engineered variety resistant to the ring spot virus was introduced. Many are convinced that only a similar intervention can save Florida's orange industry from citrus greening disease. There's also hope that humanitarian-minded genetically engineered crops, such as golden rice and the so-called super banana, could have a significant effect on nutrition and hunger issues in the developing world.

Are GMOs bad for me?

There have been no reputable scientific studies showing that genetically modified foods pose a risk to human health. One study that suggested a link between consumption of genetically engineered foods with cancer was widely considered to be flawed. The journal that published it later made a rare retraction and then proceeded to republish it.

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