What’s the latest on genetically modified foods?

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Dear Cecil: What’s the story on genetically modified organism (GMO) foods? I live in rural western Massachusetts and am exposed to a nearly constant stream of horror stories of cancerous death caused by evil GMOs, often including terrifying photos of rats with fist-sized tumors. Is there any truth to the claims of those preaching the anti-GMO gospel? Brian


Illustration by Slug Signorino

Cecil replies:

“Any” is a sweeping term, Brian. Let’s say there isn’t much truth — and there better not be. Although GMO foes may not want to admit it, the battle is over. GMOs rule.

Since the mid-1990s, GMO crops have steadily increased in terms of total crop area, with the U.S. planting more than any other country. For some crops the great majority of acreage is planted with GMO seeds — notably soybeans, with more than 80 percent of the crop worldwide of GMO origin. Biotech seed accounts for close to two-thirds of global cotton and roughly a quarter of corn and canola. In the U.S., about half of all cropland is growing GMOs, including 93 percent of the acreage for soybeans, 85 percent for corn, and 82 percent for cotton.

GMOs are plants or animals with an altered genetic code not found in nature. Genetic modification in the broad sense is nothing new; humans have been creating hybrid plants and animals for centuries, with results ranging from tangelos to killer bees. The difference with GMOs is that they’re created by direct modification of the genome rather than traditional breeding methods.

The first GMOs were made by inserting the Bt gene, which gives built-in insecticide properties to plants such as tomatoes, tobacco, corn, and soybeans. Since then, genetic modifications have been “stacked” — often via traditional crossbreeding — to produce new crop species with multiple special characteristics. For example, several GMO corn types have been crossed to create one with greater herbicide tolerance plus the Bt insecticide trait.

Gene stacking makes it possible to produce a bewildering array of GMO plants adapted for different circumstances. It’s estimated that by next year at least 24 genetic modifications of corn will be commercially feasible. If they’re quadruple-stacked that could mean more than 12,000 GMO corn varieties — which, I feel obliged to note, would be a helluva job to track.

So, what problems have been reported from GMO crops? Let’s dispose of the scariest. In 2012 French molecular biologist Gilles-Eric Séralini, a vocal opponent of genetic modification, published a paper claiming rats fed Bt-modified corn treated with Monsanto’s Roundup herbicide were much more likely to develop cancer.

The press conference at which the study was released was a transparent — and successful — attempt to manipulate public opinion. In return for a first look at the research, reporters were required to agree they wouldn’t ask Séralini’s professional peers to check his work. They were shown those photos of rats with bodies grotesquely distorted by enormous tumors, and within hours the images and other grim details had been tweeted, posted, and blogged around the world 1.5 million times.

Séralini’s methods and conclusions were widely disputed by other scientists, and the paper was eventually retracted and republished in much milder form. But the PR damage was done.

Researchers have reported other GMO-linked health issues — food allergies, stomach and uterine inflammation in pigs — but here too, reviewing scientists have seen problems with methodology. Most studies thus far have found little reason for concern.

That’s not to say there aren’t legitimate worries about GMO usage, mainly stemming from environmental impact:

  • A serious decline in the monarch butterfly population may be due to increased use of herbicides on herbicide-resistant GMO crops, which kills the milkweed plants monarch larvae feed on.
  • Chinese GMO cotton crops have seen an increase in second-tier pest insects as the primary pests have been reduced by insecticidal GMO cotton.
  • Some bugs have already developed resistance to insecticidal GMO crops in the short time they’ve been cultivated.

It’d be foolish to say nothing will ever go awry with GMO crops. The history of traditional agriculture is full of seemingly bright ideas leading to massive unintended consequences. (Example: kudzu, promoted as ground cover till 1953 and now considered a noxious weed, spreading at 150,000 acres annually.) That said, GMOs are much more closely regulated than farming experiments of old.

The hot regulatory issue now is labeling. No one can seriously dispute the public’s right to know the GMO content of consumer products, but making it happen isn’t easy — GMOs must be carefully tracked from planting to market. Laws vary among countries: the European Union requires labeling at 0.9% GMO content or more; in China any GMO content must be indicated; in the U.S. labeling is voluntary.

GMO crops have been a boon for farmers, with an estimated $78 billion in additional farm revenue worldwide from 1996 to 2010 due to reduced costs. Since 1996 total pesticide use has dropped by nearly a billion pounds. Reduced carbon emissions due to GMO crops are equivalent to taking 8.6 million cars off the road. Upcoming GMO foods include more-nutritious “golden rice,” scurvy-fighting corn, and cancer-preventing tomatoes. Whatever may go wrong, and something surely will, GMO crops are here to stay.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.