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June 29, 2017


Are GMOs Safe?

Professor Allison A. Snow, PhD

Department of Evolution, Ecology, and Organismal Biology
Ohio State University, Columbus, OH USA
What is a GMO?

Genetically modified organisms (GMOs) are organisms that have been genetically engineered by making permanent changes to their genetic code (their DNA).  Newly inserted DNA can come from other species, the same species, or artificially made sequences.  These engineered changes are inherited from one generation to the next, so the technique is really quite powerful.  Genetic engineering has been used to study both basic and applied questions in biology, medical science, and agriculture.  For example, biologists have used genetic engineering in lab experiments to add new genes, or alter existing ones, to figure out the genetic basis for disease symptoms in fruit flies and mice, with potential relevance for humans.  So far, only a few types of GMOs have been released widely outdoors, and most of these are GM crops.

What GM foods are sold commercially?

The first GM crops to be sold commercially had a few new genes that provided them with one or two unique features (traits) – resistance to the herbicide glyphosate (RoundUp) and/or resistance to insect larvae that feed on crop plants.  These traits were so successful that one or both of them now occur in most of the corn, soybean, cotton, and alfalfa grown in the USA.  Gradually, more types of genes have been introduced into these major crops and a few others.  For example, GM resistance to viral diseases has been commercialized in some varieties of papaya and zucchini.  Many foods have not been developed as GM crops, while other GMOs, like fast-growing salmon and “non-browning” apples, mushrooms, and potatoes, are expected to be commercialized soon.  By definition, foods that are labeled as organic are not genetically engineered.

How are GM foods regulated for human health and environmental safety?

So far, nearly all GM foods require regulatory approval in the USA and other countries.1,2  The goal of these regulations is to ensure that newly developed GMOs are as safe as their non-GM counterparts.1  In the USA, commercial release of GM plants, animals, or microbes requires approval from the US Department of Agriculture, the Environmental Protection Agency, and the Food and Drug Administration, if relevant.  Worldwide, there is broad consensus among scientists and regulatory agencies that currently available GM crops and food products are as safe to grow and eat as non-GM ones, although this topic remains controversial among some constituencies.1,4   More broadly, blanket statements that GM foods are either more dangerous or, conversely, much better than non-GMOs don’t make sense because the answer depends on each type of organism, the new genetically engineered trait(s), and the environment where the GMO is introduced.  Also, because only a handful of crops and traits have been commercialized, scientists have not yet studied the full range of products that are in the pipeline for environmental releases. 

How might genetic engineering change in the next 5-10 years?

Rapid changes are expected in the near future because new techniques for genetic engineering - the biggest being CRISPR/Cas9 - are cheaper, faster, and more sophisticated than previous ones.1,6,7  Much will depend on how profitable new applications are and the extent to which their commercialization is delayed or accelerated by regulatory agencies.  Recent reports by the US National Academies concluded that the current regulatory system in the USA is not prepared to scrutinize every type of GMO that may be developed in the near future, including GM microbes, plants, insects, and other animals.1,6,7  Already, scientists are working on new genetic traits that may be able to boost crop yields and nutritional content, and GM algae that will produce biofuels or pharmaceutical products.  One of the most far-reaching applications of CRISPR/Cas9 is to create gene drive systems for suppressing or eradicating unwanted species, such as mosquitoes that transmit malaria and other deadly diseases.6 

Undoubtedly, GMOs are here to stay and many members of the public will want to be more involved in decisions about when and how this super-charged technology should be used.  Meanwhile, scientists have a responsibility to carry out studies that will contribute to decision-making and risk assessment about current and future GMOs.  Whenever someone asks me whether I think GMOs are safe, I always start with: “it depends.”


1.     The National Academies. Genetically Engineered Crops: Experiences and Prospects. National Academies Press (2016). Available at

2.     Camacho, A., Van Deynze A., Chi-Ham, C., & Bennett, A.B.  Genetically engineered crops that fly under the US regulatory radar.  Nature Biotechnology 32:1087-1091 (2014).

3.     Giddings, L.V. & Miller, H.  US National Academies report misses the mark.  Nature Biotechnology 34:1226-1228 (2016).

4.     Gould, F., Amasino, R.M., Brossard, D., et al. Elevating the conversation about GE crops.  Nature Biotechnology 35:302-304 (2017).

5.     Vincelli, P., Jackson-Smith, D., Holsapple, A.  National Academies Report has broad support.  Nature Biotechnology 35:304-306 (2017).

6.     The National Academies.  Gene Drives on the Horizon: Advancing Science, Navigating Uncertainty, and Aligning Research with Public Values.  National Academies Press (2016).  Available at

7.     The National Academies.  Future Biotechnology Products and Opportunities to Enhance Capabilities of the Biotechnology Regulatory System.  National Academies Press (2017).  Available at:

8.     P., Jackson-Smith, D., Holsapple, A.  National Academies Report Has Broad Support.  Nature Biotechnology 35:304-306 (2017).

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