Few food-policy debates are as rancorous as the debate over genetically modified organisms (GMOs). Are GMOs in our food harmful? Harmless? Somewhere in between? And is it even possible to tell which foods contain them? Here's a primer to get you up to speed on GMOs—what they are, where they're found, and what's known about their effect on the environment and human health. If you decide you want to avoid GMOs, we'll tell you how to do that, too.
What are GMOs, anyway?
Genetically modified organisms are plants or animals—even fungi and bacteria—that have been genetically altered in order to take on specific characteristics. For example, scientists might insert genes from one plant into an unrelated plant to help the plant develop a resistance to insects or herbicides. Genetic modifications can also increase the plant's nutrients or its yield. Corn and soybeans are among the most heavily and frequently modified food plants in the world, although some of the modifications are geared toward industrial uses like ethanol, which is made from corn and other plants.
How long have GMOs been around?
The history of agriculture is a tale of crop modification. Humans have been manipulating the traits of plants—and, of course, animals—for millennia, primarily through interbreeding. But only in the past few decades have scientists been able to modify organisms on the genetic level, targeting specific gene-driven characteristics such as size, growth rate, and resistance to spoilage. The first genetically modified food marketed in the U.S. was the Flavr Savr tomato, introduced in the mid-1990s. (The Flavr Savr was not profitable and was discontinued just a few years later.)
Which foods grown in the U.S. are most likely to contain GMOs?
Corn and soy lead the pack—an estimated 85 percent of corn grown in the U.S. is modified—and several other crops not far behind. Genetically modified sugar beets, for instance, account for as much as half of the country's sugar production, while roughly 90 percentof the canola plants in North America are genetically modified. (Organic canola oil, by definition, cannot be produced from genetically modified plants—but it makes up only a small portion of the market. In Europe, on the other hand, all canola oil is produced from non-modified plants.)
In addition, foods that include elements or a mix of the crops above, such as corn syrup, will almost certainly include GMOs.
Are GMOs safe for the environment?
Critics of GMOs cite a number of potential adverse effects on the environment, including a decrease in biodiversity as industrial farms around the world rely on fewer, modified "super crops." Another risk is that genes from modified crops might transfer to their wild relatives or harmful wild plants such as invasive weeds. This could make the weeds more resistant to herbicides or insects, and disrupt the ecosystem by forever altering the wild relatives of crops.
The Environmental Protection Agency (EPA) is authorized to regulate GMOs as chemical substances, and in most cases has determined that cross-pollination is not a risk in the U.S.
Are GMO foods safe for people?
Like foods derived from traditionally bred plants, foods from genetically engineered (GE) plants must meet certain Food and Drug Administration safety requirements in order to be marketed. But any actual evaluation of GMO foods by the FDA is voluntary, and the agency only tests GMO foods brought to it by developers of GE plants.
To date, researchers around the world have conducted roughly 2,000 studies around the safety of GMOs—in terms of human consumption, evidence of allergens, effect on biodiversity, and more—with the vast majority of those studies determining that GMOs do not appear to pose a threat to human health or the environment. Still, there are some scientists—a vocal minority—who remain dubious. For such an important question, certainly more research is needed.
An important concern is that the prevalence of GMOs in corn and soybean farming is increasing our exposure to potentially carcinogenic herbicides, since many GMO corn and soybean seeds are engineered to withstand the weed-killing ingredient glyphosate (better known as Roundup). That allows farmers to spray Roundup without fear of harming their crops. (Chemical giant Monsanto makes both Roundup and the GMO seeds designed to withstand it.) In a March 2015 report, the World Health Organization declared glyphosate "probably carcinogenic to humans," a finding that Monsanto strongly contested.
Can I tell from the label whether a food contains GMOs?
There is currently no mandatory labeling of GMO foods in the United States. In fact, voters in states like Oregon, Washington, Colorado, and California, which produces nearly half of the fruits, nuts, and vegetables grown in the U.S., have rejected ballot measures that would have required labeling of foods containing GMOs. That's in contrast to more than 60 nations around the world—as diverse as Australia, Ireland, Senegal, and South Korea—that require GMO labeling. The U.S. remains one of the only industrialized countries in the world without mandatory labeling.
If I want to avoid GMOs, how do I go about it?
Short of growing your own food, the simplest (if not necessarily the most economical) way to avoid GMOs is to buy certified organic foods, which by definition contain no genetically altered ingredients. That said, some organic farmers in recent years have reported "unintended GMO presence" in their crops, likely contaminated from wind-borne seeds that blow in from non-organic neighboring farms.
Consumers concerned about genetically modified crops can also look for foods certified with the Non-GMO Project Verified seal, which you can now find on products from more than 1,500 brands nationwide.
Finally, you can refer to the Environmental Working Group's Shopper's Guide to Avoiding GE [Genetically Engineered] Food. This is a solid, one-stop resource for information on what to look for—and what to avoid—when shopping for food.