By far, the biggest use of GMO technology is in large-scale agricultural crops.

A genetically modified organism, or GMO, is an organism that has had its DNA altered or modified in some way through genetic engineering.

In most cases, GMOs have been altered with DNA from another organism, be it a bacterium, plant, virus or animal; these organisms are sometimes referred to as "transgenic" organisms. Genetics from a spider that helps the arachnid produce silk, for example, could be inserted into the DNA of an ordinary goat.

It sounds far-fetched, but that is the exact process used to breed goats that produce silk proteins in their goat milk, Science Nation reported. Their milk is then harvested, and the silk protein is then isolated to make a lightweight, ultrastrong silk material with a wide range of industrial and medical uses.

The dizzying range of GMO categories is enough to boggle the mind. CRISPR, a novel genome editing tool, has allowed geneticists to breed GMO pigs that glow in the dark by inserting jellyfish bioluminescence genetic code into pig DNA. CRISPR is opening doors to genetic modifications the likes of which were unimaginable just a decade ago.

These are more comparatively wild examples, but GMOs are already very common in the farming industry. The most common genetic modifications are designed to create higher yield crops, more consistent products, and resist pests, pesticides and fertilizer.

Genetically modified food

According to the National Library of Medicine (part of the National Center for Biotechnology Information, or NCBI), genetically engineered, or GM, foods are those that have had foreign genes from other plants or animals inserted into their genetic codes. This has resulted in foods that are consistently flavored, as well as resistant to disease and drought.

However, the NCBI also maintains a list of potential risks associated with GM foods, including genetic alterations that can cause environmental harm. Specifically, it's possible that modified organisms could be inbred with natural organisms, leading to the possible extinction of the original organism. For instance, the banana tree is propagated entirely through cloning methods. The bananas themselves are sterile.

By far, the biggest use of GMO technology is in large-scale agricultural crops. At least 90% of the soy, cotton, canola, corn and sugar beets sold in the United States have been genetically engineered. The adoption of herbicide-resistant corn, which had been slower in previous years, has accelerated, reaching 89% of U.S. corn acreage in 2014 and 2015, according to the U.S. Department of Agriculture.

One of the biggest draws for widespread adoption of GMO crops is pest resistance. According to the World Health Organization, one of the most widely used methods for incorporating pest resistance into plants is through Bacillus thuringiensis (Bt) genetics, a bacterium that produces proteins that repel insects. GMO crops that are modified with the Bt gene have a proven resistance to insect pests, thus reducing the need for wide-scale spraying of synthetic pesticides.

Are GMOs safe?

Anti-GMO activists argue that GMOs can cause environmental damage and health problems for consumers.

One such anti-GMO organization is the Center for Food Safety, which calls the genetic engineering of plants and animals potentially "one of the greatest and most intractable environmental challenges of the 21st century."

"Genetically modified foods have been linked to toxic and allergic reactions, sickness, sterile and dead livestock, and damage to virtually every organ studied in lab animals," according to the Institute for Responsible Technology, a group of anti-GMO activists.

"Most developed nations do not consider GMOs to be safe," according to the Non-GMO Project. "In more than 60 countries around the world, including Australia, Japan and all of the countries in the European Union, there are significant restrictions or outright bans on the production and sale of GMOs."

As You Sow is a nonprofit environmental watchdog focusing its research on how corporate actions affect our environment, including food production. According to Christy Spees, a program manager with As You Sow, GMO foods are dangerous "because the modifications are centered around resistance to toxic substances, such as pesticides and certain fertilizers. When dangerous chemicals are applied, plants use them to grow, and the food itself can be detrimental to our health."

Why GMOs are good

Many scientific organizations and industry groups agree that the fear-mongering that runs through discussions of GMO foods is more emotional than factual. "Indeed, the science is quite clear: crop improvement by the modern molecular techniques of biotechnology is safe," the American Association for the Advancement of Science (AAAS) said in a 2012 statement.

"The World Health Organization, the American Medical Association, the U.S. National Academy of Sciences, the British Royal Society, and every other respected organization that has examined the evidence has come to the same conclusion: Consuming foods containing ingredients derived from GM (genetically modified) crops is no riskier than consuming the same foods containing ingredients from crop plants modified by conventional plant improvement techniques," according to the AAAS.

Others point to the benefits of sturdier crops with higher yields. "GM crops can improve yields for farmers, reduce draws on natural resources and fossil fuels and provide nutritional benefits," according to a statement on the website for Monsanto, the world's largest manufacturer of GMOs.

Monsanto and other agriculture companies have a financial stake in the research and messaging surrounding GM foods and have the resources to fund research that reinforces their narrative. However, although there are plenty of scientific data that demonstrates the safety, efficacy and resilience of GM crops, genetic modification remains a comparatively new scientific field.

GMO labeling debate

The argument over the development and marketing of GMO foods has become a political hot potato in recent years.

In November 2015, the FDA issued a ruling that only requires additional labeling of foods derived from genetically engineered sources if there is a material difference — such as a different nutritional profile — between the GMO product and its non-GMO equivalent. The agency also approved AquaAdvantage Salmon, a salmon designed to grow faster than non-GMO salmon.

According to Monsanto, "there is no scientific justification for special labeling of foods that contain GM ingredients. We support these positions and the FDA's approach."

According to GMO Answers, an industry group comprised of Monsanto, DuPont, Dow AgroSciences, Bayer, BASF, CropScience and Syngenta, GMO agricultural products are "by far the most regulated and tested product in agricultural history."

Additionally, their website states that "many independent scientists and organizations around the world — such as the U.S. National Academy of Sciences, United Nations Food and Agriculture Organization, World Health Organization, American Medical Association and the American Association for the Advancement of Science — have looked at thousands of scientific studies and concluded that GM food crops do not pose more risks to people, animals or the environment than any other foods."

The political issue that GMOs have become is almost as conductive as the scientific debate. However, after much discussion among various lawmakers across the U.S., the National Bioengineered Food Disclosure Standard (NBFDS) was passed into law at the beginning of 2019.

According to the NBFDS current federal statutes, starting in 2020, all food must bear a BE (bioengineered) label if it contains more than 5% bioengineered material. States are free to impose their own labeling requirements as well, though it seems that most jurisdictions are waiting for federal laws to be implemented before working on new legislation. One thing is for certain: the scientific and political discussions surrounding GMO foods aren't going away any time soon.

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This article was updated on July 8, 2019 by Live Science Contributor Mark Davis.