Genetically Modified Organisms (GMOs)

A controversial sector of agricultural production.

Genetically Modified Organisms can be a hot topic! You might have already heard “GMO” tossed around in conversation.

Image of someone scratching their head and wondering, "Are they safe? Healthy? Sustainable?" — image by Syawaluddin from the Noun Project

Don’t let the noise confuse and mislead you!

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GMOs: What are they?

What does “GMO” really mean? You might already know what “organism” means.

But what makes an organism “genetically modified”? This means the organism’s genes, or DNA, have been changed.

Organism: a living being. It could be a microbe, a plant or an animal.

Scientists do this to change some of the organism’s qualities. Sometimes they do this by adding in genes from other organisms.

Genetically Modified Organism: a plant or other organism that has been changed on purpose (usually in a laboratory)

If you read more, you might see the term “genetic engineering,” or see GMOs called transgenic organisms. But we’ll stick to the term “GMO.”

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GMOs: The Pros

Why would we want to change a plant’s DNA? There are tons of reasons.

Image of tomato being injected with desirable qualities: extra red color, drought resistance, resistance to pests, and more vitamins — Images by Adam Zubin, Vectors Market, ni.zi, Koson Rattanaphan, and Georgiana Ionescu from the Noun Project

Some GMOs are helpful to farmers–they help plants grow. They might:

Produce more food
Need less water
Change the way plants look or taste: genetic modification could make a tomato redder and more juicy-looking. Or it could keep a potato from browning when you cut it open.
Help farmers to manage pests

Some GMOs are changed to give them resistance to pesticides. That means pesticides won’t kill them.

For example, some crops are resistant to Roundup (a common pesticide). These are coined as “Roundup Ready.”

Pesticide: a product designed to kill a pest, like a weed, an insect, or a microorganism.

So what? This way, farmers kill pests like weeds without worrying that they will kill their crops. Farmers can spray a whole field of Roundup Ready corn with Roundup and only the weeds will die!

Image of corn and weeds being sprayed by Roundup; the weeds are poisoned but the corn survives — Images by Annette Spithoven, Kevin, and ahmad rojali from the Noun Project

That makes it cheaper, faster, and easier for the farmer. But it also has some consequences.

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GMOs: The Cons

Remember how huge fields can be—hundreds of acres or more. So when you spray that whole field that is a lot of pesticides!

That can affect workers…

The workers who spray pesticides are regularly using them, putting them at high risk of exposure. Some workers don’t even have protective equipment to keep them safe.

Agricultural workers also often live near the fields where pesticides are being sprayed. This means that they may be exposed to pesticides when they aren’t working, too.

…and it can also affect the environment and the public

Like fertilizers, pesticides don’t just stay on the plants. When it rains, the pesticide might wash into our soil and our waterways. This is called runoff.

Runoff: when extra liquid that soils can't absorb flows into nearby waterways like rivers and lakes.

Runoff pollutes waterways (think lakes and rivers), affecting the health of people and the environment.

People might eat fish that have eaten pesticides and be exposed to toxic pesticide residue. Or, runoff with pesticide residue can ruin ground or surface water that provides drinking water to entire communities.

Outline of Missouri with a poison water drop and a dead fish. Text reads: "For example: Mark Twain Lake, in Missouri, provides water to people in 14 counties. But because of pesticide runoff, less than 25% of the lake's water is safe to drink." — Images by Andrejs Kirma, Gemma Evans, and Linseed Studio from the Noun Project

Another issue that might come up is pesticide resistance.

Pesticide Resistance: when an individual pest survives a pesticide that would kill other members of its species.

Some weeds might survive pesticides. Maybe that doesn’t matter in the short term–most of the weeds are still killed.

But in the long term, it can become a problem. When a field is sprayed over and over again, the surviving weeds reproduce. Their genes are passed onto their offspring, who then survive pesticide applications too!

This leads to pesticide resistance.

Line drawings of plants with strong arms. Text reads: "Did you know? When only a few pesticide-resistant plants survive for generations, it leads to big groups of pesticide-resistant weeds." — Images by Deemak Daksina and Romaldon from the Noun Project

To kill these super-powered weeds, we would have to make a new pesticide.

We can also change a plant so it can poison insects that eat it. Instead of spraying on the pesticide, we make the plant itself resistant to certain pests.

Line drawing of beetles on a leaf. A red arrow shows a dead beetle falling off. — Images by Amethyst Studio and Slidicon from the Noun Project

One common plant with the quality of insect resistance is “Bt corn,” which has a bacteria in it that is toxic to certain pests. This form of GMO actually reduces pesticide use.

But adding pest resistance to a plant comes with its own issues. When a pesticide is part of a plant’s DNA, it doesn’t break down over time. Year after year, this exposes insects to the same pesticide.

Remember pesticide resistance in plants? Well, that can happen in insects, too. Some insects survive after eating the pesticide-infused plant. When those are the only insects left in the environment, they pass that ability to survive onto their children.