Risks of genetic engineering

By Anastasia Bodnar and Karl Haro von Mogel

It seems like every news article about genetic engineering gives a nod to unknown risks to the environment or human health that are unique to genetic engineering. What are those risks, and are they really unique?

Before we get into the details of specific potential risks, there are three things we need to consider.

  1. Is a risk unique to genetic engineering as a whole or risks of individual traits of categories of traits? Each individual trait, whether bred or engineered, must be examined for safety and appropriateness in the situation in which it will be used.
  2. What is the risk compared to alternatives? Risk associated with a genetically engineered trait may be less than the risk associated with a practice that it will replace.
  3. What is the source of the risk? Is it something inherent in the trait or are there external factors?

Gene transfer

One of the most common concerns is with the process of genetic engineering – the transfer of one or more genes from one species to another and potential for unintended genetic changes during the process. While it is possible that unintended changes can occur, this risk is not unique to genetic engineering. Natural and induced mutagenesis as well as traditional breeding methods can also introduce unintended genetic changes, resulting in additional genes being turned on or off, deletions, duplication, and other changes in the genome. Crossing crop plants with wild relatives can introduce genes and proteins that have never been in the human food supply, as can genes inserted through genetic engineering.

Monoculture farming

In the United States and Canada, genetically engineered crops are generally used in farms grown with a monoculture system. However, these farms were monocultures before the advent of genetic engineering and would continue to be monocultures if genetic engineering disappeared tomorrow. Monoculture farming is a problem in and of itself, separate from genetic engineering. In India and Africa, genetically engineered crops (specifically Bt cotton and Bt maize) is grown in a variety of systems. Virus resistant papaya is grown in both larger production farms and in people’s backyards.

Pest resistance

Whenever a pesticide is used year after year in the same place on the same target populations, resistance to that pesticide will develop. This is not a problem specific to genetic engineering. With any pesticide, and with any genetically engineered crop that involves pests, the pesticides must be rotated to prevent any resistance genes that develop from spreading throughout the population. While crops resistant to glyphosate have resulted in a switch away from other herbicides to glyphosate which has resulted in an increase in glyphosate resistant weeds, this is not due to genetic engineering. The problem is a lack of integrated pest management strategies that incorporate a variety of solutions.

Microorganisms and other non target organisms

Another concern that some people have is about genetically engineered crops is that they might have a negative impact on soil microorganisms, beneficial insects, and other wildlife. It is possible that some genetically engineered traits might impact wildlife. Of course, each trait must be assessed individually and we must determine what is the relative risk compared to other options. For example, it is possible that a particular type of Bt in maize would have an effect on soil microorganisms compared to a similar maize without Bt, but that many pesticides against root worms would be even more disruptive for soil microorganisms.

There is one particular example that we need to address in this section. We’ve all heard the story about Monarch butterflies being harmed by genetically engineered crops. First, it was claimed that Bt in pollen harmed the butterflies. Thankfully, those claims were wildly exaggerated – the result of experiments that did not match real-world conditions. Next, it was claimed that monarchs are harmed because the herbicide glyphosate is being used to kill weeds, including the milkweed that Monarchs need to live. However, this is not a problem of glyphosate resistant crops. It is a symptom of a larger problem – that of sterile lawns without weedy flowers that feed butterflies and of farms that are planted border to border without much wild land between.

Modifying biochemical pathways

Plants have enormously complex networks of biochemical pathways that create almost every substance that the plants need. These pathways, like a network of roads and highways, are interconnected and have only begun to be understood. Some of the kinds of genetically engineered crops that are beginning to emerge involve modifying these pathways to produce more of a desired substance or less of an undesired one. For instance, some work on Cassava focuses on reducing the amount of toxic compounds in the roots, and the well-known Golden Rice Project  involves boosting beta-carotene in the grain to combat vitamin deficiency. It is possible that modifying the levels of these and other substances in the plant can have effects on other parts of the system, and modify the plant in some undesirable way.

This kind of risk must also be taken in the context of the history of plant breeding. The crops we eat today are replete with examples where drastic changes in biochemical pathways have occurred through simple breeding with no understanding of the underlying biochemical mechanisms. For instance, carrots were not originally orange but white and purple in color. The accumulation of genetic mutations, and the long process of breeding resulted in a nutritionally modified vegetable that is today one of the richest sources of beta-carotene in our diets today. The biochemical pathway that produces beta-carotene in orange carrots and Golden Rice is the same, and the risks involved in modifying such pathways would therefore be similar.

What if it works?

Modifying the nutritional content of foods through genetic engineering has the potential to reduce suffering and improve human welfare. Modifying a plant to resist insects has the potential to reduce insecticide sprays and improve yields and/or food security. There are countless other risks involved in agriculture and food that are dealt with on a regular basis. So when discussing the risks involved in genetic engineering, it is important to consider the risk that it will succeed in reducing or mitigating these other risks.

When evaluating the risk of doing something, you should also consider the risks involved with not doing something. As with driving a car or having electricity in your home, there are benefits that come along with the risks of genetic engineering – and all of these need to be taken into account together.

These are just a few examples of broad claims of risk that are often attributed to genetic engineering that are much more complex issues when you examine them more closely. Can you think of others? Lets hear them in the comments.


  1. Another “risk” — and one that many discussions boil down to — is the control of the seeds (which is then often extended to the question of who “controls” the food supply and the declaration that Monsanto is evil), whether through legal agreements or “terminator” seeds (GURTs). People do not know, understand, or care to acknowledge that genetic engineering is a breeding approach that, per se, has nothing to do with intellectual property rights (IPRs), not to mention that Monsanto is but one company (and not all mobile phones are from Apple, either).
    There are existing, non-controversial technologies (hybrids) that make the saving of seeds pointless, and there are conventionally bred seeds for which the use of farm-saved seeds is limited by legal agreement. In contrast, the “terminator” technology is not applied anywhere, and there are also many instances where the seeds of GM crops can/could be saved because it was developed by public institutions (some Bt crop varieties in India, Golden Rice once it is released, etc.) or because the developer failed to patent their product in the corresponding jurisdiction (e.g. HT soybeans in Argentina). This means the “risk” of patents in agriculture is largely independent from the breeding approach that was used to develop a new crop variety.
    Moreover, nobody forces farmers to purchase seed that are protected from re-saving, whether “naturally” protected hybrids or legally protected other crops. If farmers do so, they do it because the improved seed offers them advantages, such as higher average yields or lower input costs (such as insecticides or labour), which can compensate possibly higher seed prices, i.e. farmers are doing an investment, or farmers purchase the seed because it offers more convenience in crop management. Farmers do not convert their whole acreage to a new seed at once, i.e. if they are not happy with the results they can always switch back to farm-saved seeds. (Or at the very least get farm-saved seeds from neighbours etc.) That is, going for protected seed is not a one-way street.
    Finally, to protect farmers from oligopolistic markets where the pricing may be biased towards the interest of the seed industry, the solution is not to erect market-entry barriers (and aggressive opposition by minor but vocal interest group probably counts as such, not to mention strict regulation that make the approval of new crops and expensive and unpredictable process). Such barriers prevent newcomers from entering the field and stimulate competition, and they cement the market power of existing companies.
    The solution would rather be to facilitate development, authorisation and commercialisation of new GM crops to encourage new players to develop new products, which offers farmers greater choice and drives down prices. More funding of public research in that area to generate knowledge for which IPRs are waived, or re-thinking current IPR regulation are other possibilities. However, the studies that have been carried out so far have not shown any particular abuse of market power in the market for GM seeds; the gains from cultivating GM crops are shared between developers, farmers and consumers.
    [editors’ note – paragraph breaks added to make for easier reading]

  2. One thing not addressed here is more about (mis-)communication of science information and its effect on beliefs than about the specifics of GM science. Part of it is how polarized every discussion seems to be, whether it’s the comments on any news site or blog (around any topic), or the guests on TV and radio news shows. There is the problem of everything being hyped to the extreme and reduced to tweet-length snippets.
    One issue exacerbated by the latest Seralini paper is the conflicting messages non-academics get about science and research. Pro-GM people always say that real science comes from experimental findings published in the peer-reviewed literature. “Just show me one peer-reviewed study that shows risks of GMs, just ONE!” And then when someone raises the Seralini paper, they hear “that study was so OBVIOUSLY flawed it should never have been published!” I think that paper is a setback for everyone. The worst thing may be an increase in the chilling effect on legitimate inquiry into potential risks of current or future GM. What researcher, tenured or not, will want to risk their career on something that is critical of the establishment? (This is not an argument for loosening standards, btw.)
    So how can scientists (in any field) better communicate with intelligent, open-minded people? I know plenty of otherwise bright people who hear only negative messages about GM. These people are not enemies of science. They tend to be pro-science and pro-technology, both passively and actively. (Many of them *are* scientists.) They are not anti-vaccine. The are not climate deniers. They are not luddites. They are not anti-evolution, or young-earthers, or otherwise religious nutjobs. They are not birthers or moon-landing-deniers. They know the difference between organic food and volatile organic compounds. Their largest deficiencies are that they have minimal knowledge of genetics, and no free time to learn it (finding jobs / getting tenure are more important). They spend their days reading journal articles, not Mercola.com. Based on the stenography of the news media around the Seralini paper, they’re clearly not reliable. What are some other channels?

  3. The fear of new allergens being produced in GM food is often expressed in comments on blogs and forums. Misleading photos on anti-GM sites that suggest fish parts are being inserted into strawberries, for example, is partly to blame. I’ve had lots of allergies in my life that mostly went away on their own. I’ve had lots of testing and know that allergy testing is not that accurate (that’s what the allergist told me). Anyone can be allergic to anything. However, from my limited understanding about GM traits, it doesn’t seem like they would be any more allergenic than anything else, but I could be wrong. Any explanation (in layman’s terms) of the results of allergen related to GM crops would be appreciated. Thanks.

  4. Cool, thanks! I wondered why there was a “Preview” button, but once I had submitted the comment and I saw the big chunk of text I knew why… (Hadn’t seemed so much when I wrote it.)

  5. What researcher, tenured or not, will want to risk their career on something that is critical of the establishment?

    Anyone, as Kevin Folta often points out, who’d quite like a nobel prize. (the reason you have no nobel prizes in the field is because all the GMOs released to date are safe)
    Seralini isn’t slated because he questioned the establishment, he’s slated because he did terrible science combined with underhand PR release of said science.
    In the scientific world it is accepted practice to have your work heavily scrutinized, to have your figures taken apart bit by bit, your statistics poured over.
    If it comes out the other side intact, or improved, then the process worked and you did good science. If it is left in tatters then the process worked and you didn’t do good science.

  6. Another “risk” is the loss of agricultural biodiversity. People fear that a smaller number of new varieties will replace a larger number of “traditional” varieties. What is often overseen is that seed companies breed their elite germplasm into locally adapted varieties or create many different varieties that satisfy the needs and requirements of different farmers in different agro-ecological zones. (Again a situation where more breeders are better than a few…)

  7. It’s the tentative nature of scientific findings that I think are part of the disconnect. Laypeople get the impression that a peer-reviewed article is the end of the process, but in reality it’s the beginning. And while laypeople are skeptical of corporate-sponsored papers, they don’t realize that scientists are skeptical of EVERYBODY’s papers. (See, e.g., http://www.nature.com/scitable/blog/theprometheancell/a_humble_rant_re_spin)
    That said, I’ve never met a single scientist whose goal is a Nobel (even the ones I’ve met who have them). And the profile of Nobel winners is not that of a young, pre-tenure faculty member. I also don’t get the sense that people formulate their research directions in relation to disproving others’ work. That would seem to be heading down the same path as an activist like Seralini, who begins with an agenda rather than a hypothesis. My original point was that the Khunian nature of established science naturally inhibits inquiry in directions that are de facto ‘forbidden’, to the point that data that contradict established theory may be reflexively viewed as anomalous or erroneous, even by the investigator herself.

  8. The following is what one physician wrote today on another forum. He posted something similar a month or two ago, however he did call the latest Seralini study bogus. Another physician pretty much follows the anti-GM line while blasting alternative medicine as pseudoscience. Go figure.
    “Unproven technology speaks for itself.
    We simply have no idea what effect playing around with genomes of plants in the wild will have on the complex dynamics that control the biosphere. None. We don’t even understand those dynamics. Our ignorance is demonstrated over and over again, every time theory and reality clash.
    For simple and obvious example, the sophisticated models we use to predict the impacts of global warming on the melting of polar ice are not accurate. One would think that those models would be simple exercises in physics. But we don’t understand our world.
    In the absence of understanding of how plants share genes and in the absence of understanding how those shared genes impact both the plants and their environment thousands of generations down the line, we have no way of predicting what will be the impact of releasing genetically modified plants into the environment.
    Our many-times grandchildren will know. But we won’t.
    Unproven technology.
    We think we know more than we do. We think it’s OK to play with the building blocks of life itself, even though we don’t have the foggiest idea what we’re doing. We are literally playing God.
    H-u-b-r-i-s. “

  9. Debbie, that’s the whole point of this post. People want to attribute some special level of risk and uncertainty to genetic engineering, but the truth is, we don’t know the long term effects of most things that humans do.

  10. “We are literally playing God.”
    The good old argumentum ad populus.
    (or black and white, I guess, for todays modern gamer)
    Playing god is waaaay more fun and time consuming than genetic engineering, which frankly is a lot more like sim-farm.

  11. After I wrote this yesterday I heard an interview with Frances Ashcroft, who said that when she ran her original experiments on ion channels and glucose, “I actually thought that there was something wrong with the experiment. I didn’t at the time realize that what I had predicted might happen, had happened. […] I was unbelieveably excited. […] I was over the moon, I couldn’t sleep. But by the next morning, of course, I thought it was all a mistake. […] The thing is that you always think that you’ve made a mistake — that something must have gone wrong in the experiment, that this wasn’t actually a real breakthrough, because breakthroughs happen so rarely that I’d done something wrong in the experiment. So you have to do what everybody does who’s a scientist, and that’s repeat the experiment again and again and again. And I was lucky: I was right, and the experiment has been repeated many hundreds and thousands of times by different people throughout the world.”
    (begins at approx. 06:00 mark)

  12. There does seem to be a lot of undue concern about trans-species gene transfer. Some are claiming that GM food will transfer genes to the e-coli in our guts. But, let’s consider if this is true. If so, it would also be true for any food. After all the genes themselves don’t know they are GM or not.
    This would indeed explain why every time i eat beef, my ass moos ! 🙂

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