Review of 10 years of GMO research - no significant dangers

Posted on November 14, 2013

by Michael Simpson

One of the tactics of the GMO (genetically modified organisms, usually crops–some people use the term GM instead) refusers is that “there’s no proof that GMO’s are safe.” Typically, in a debate, the side making the assertion (those that say GMO’s are unsafe) are responsible for the evidence that supports their contention. But, the anti-GMO gang relies upon the Argument from Ignorance, trying to force the argument to “if you can’t prove that they’re safe, they must be unsafe.”

Even though I don’t necessarily like arguing with logical fallacies, I did provide an exhaustive list of high-quality peer-reviewed articles that clearly stated that genetically modified crops are safe. But that’s never enough.

In the world of scientific research, the absolute highest quality evidence are meta reviews, which are methods to contrast and combine results from a wide swath of peer-reviewed studies which may be useful in identifying patterns, sources of disagreement and other relationships. Since meta reviews combine the results from a larger number of studies, they can be more statistically significant. So, if there only was a high quality, peer-reviewed meta review about the safety of GMO foods!?!?

Well, there is one. In a meta-review recently published in a peer-reviewed, high impact factor journal, Critical Review of Biotechnology, where the authors collected and evaluated 1,783 research papers, reviews, relevant opinions, and reports published between 2002 and 2012, a comprehensive process that took over 12 months to complete. The review covered all aspects of GM crop safety, from how the crops interact with the environment to how they could potentially affect the humans and animals who consume them.

And their conclusion?

The scientific research conducted so far has not detected any significant hazards directly connected with the use of genetically engineered crops.

According to an interview with the lead author, Alessandro Nicolia, an applied biologist at the University of Perugia in Italy, “Our goal was to create a single document where interested people of all levels of expertise can get an overview on what has been done by scientists regarding GE crop safety. We tried to give a balanced view informing about what has been debated, the conclusions reached so far, and emerging issues.”

The article provided other important results:

  • The scientific literature was heavily in favor of the safety, to both the environment and to humans, of GM based agriculture.
  • Environmental impact studies are predominant in the body of GM research, making up 68% of the 1,783 studies. These studies investigated environmental impact on the crop-level, farm-level and landscape-level. Nicolia and his team found “little to no evidence” that GM crops have a negative environmental impact on their surroundings.
  • Little to no evidence that GM agriculture harms native animal species.
  • Non-GM crops actually tend to reduce biodiversity to a higher degree.
  • Genes of GM crops can spread to wild plants, other crops and microorganisms. However, the authors state that this type of gene transfers occurs naturally all the time with non-GM crops. In fact, local plant genotypes get supplanted by non-GM crops genes. The study also stated that wild plant populations frequently mutate and become resistant to herbicides, so they form their own genetic modification (what we call evolution). Soil bacteria can take genes from all kinds of plants and other microorganisms, but that’s not harmful, it’s part of how evolution proceeds.
  • GMO crops are safe for humans and animals to consume. Before any GM crop can be shipped to a grocery store, they must be shown to be substantially equivalent to non-GM foods. In other words, GM crops should have no toxic biomolecules and have similar (if not more) of the nutrients found in the non-GM foods. This is known as substantial equivalence, and the Italian researchers could not find a single credible paper that demonstrated that GM foods had any detrimental effect on animals or humans that consume them.
  • DNA from GM crops cannot be incorporated into our DNA. This is one of the most ridiculous (and pseudoscientific) claims of the anti-GMO groups. We ingest a lot of DNA every day (from meats to raw plants), and it just doesn’t happen. Most of the DNA is broken down in the digestive tract. And if it were so easy to inject genes into the human genome, then we could really stop spending money trying to figure out how to transfer genes for medical purposes. But what we found out about gene transfer is that it’s so difficult that it may not ever be useful as a medical treatment. What makes anyone think that consuming transgenic DNA (which really is just DNA) will somehow do something that just can’t be done intentionally.
  • In the food and feeding category, the team found no evidence that approved GMOs introduce any unique allergens or toxins into the food supply. All GM crops are tested against a database of all known allergens before commercialization and any crop found containing new allergens is not approved or marketed.

This is real evidence, the highest level of scientific evidence. It’s not based on opinion or irrational claims or logical fallacies. This is as close to a scientific consensus as you will find. And once again, even if science were some kind of democracy (and it isn’t) the vote would be 98% in favor of the safety of GMOs. Inventing a controversy, where there is none except in the minds of the anti-science crowd, doesn’t help the case of the GMO refusers. Strong, repeatable, and published scientific evidence does.

Key citations:
Nicolia A, Manzo A, Veronesi F, Rosellini D. An overview of the last 10 years of genetically engineered crop safety research (pdf). Crit Rev Biotechnol. 2013 Sep 16. [Epub ahead of print] PubMed PMID: 24041244. Impact factor=5.095.
Illustration source:

This article was republished with the author’s permission.

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Michael Simpson
is author of The Skeptical Raptor blog
  • Talia

    Posted on 16/12/2013

    Hi There, I am looking for these rare scientific peer-reviewed studies that GMOs are unsafe. Can somebody post some links to them (if they exist)? Thanks!

  • Michael S

    Posted on 27/11/2013

    Three comments: 1) Systematic reviews attempt to remove bias by only including the best designed, scientifically strongest articles to include. 2) Since there are few, if any, high quality studies published in high impact journals that show there are dangers to GMO

  • Joe

    Posted on 26/11/2013

    You seem to be saying that this one review comprehensively covers all existent scientific research in the field, and shows that any paper which disagrees with your view point is not credible. Is that really your contention? Your tabloid-esque writing style makes clear your disdain for those who are wary of GMOs, but in making your partisanship so clear you undermine the credibility of your argument. I doubt the paper you cite takes such a cheap and unscientific approach to the subject.