Why no one will ever “prove that GMOs are safe”

Water has never been proven safe. Image by Konstantin Stepanov via Flickr.
Water has never been proven safe. Image by Konstantin Stepanov via Flickr.

When discussing transgenic crops, I regularly get asked to provide a paper that “proves” that GMOs are safe. Whether you want proof that biotech crops, organic bananas, or conventional peaches are safe, I cannot provide you with such a paper. Safety is a relative term and is generally defined as the absence of risk or harm. As such, asking for proof of safety is, in essence, asking someone for proof of the absence of risk. The risk of what ever is being evaluated is measured in relation to other options, not against a theoretic idea of “perfectly safe”. Relative risk is scientifically determined by examining the evidence at hand: experiments are performed to determine the impact of a substance on health, environment, etc and the data from these experiments are assessed to determine if the substance causes harm.
Scientifically, nothing is truly 100% safe. To explain why, we’re going to do an exercise and try to prove that water is safe. The first thing to keep in mind is that there are many aspects to water safety: impact on health, water transportation, water treatment, proper water storage, etc. For our example, we’re going to select “impact on health”.
Then, we have to come up with a null hypothesis. It may seem counter-intuitive and the double-negatives in the explanation below suck, however the baseline for much of research is that there’s no impact or no difference. It’s the researcher’s responsibility to disprove that hypothesis, ie. to show that there is a difference or that there is an impact. For example, if you want to find out if kids who watch TV are more prone to hitting, your null hypothesis could be “watching TV does not increase aggression”. So for our exercise, our hypothesis will be “Drinking water does not cause cancer”.
Next, we narrow down the hypothesis to a question that we can actually test. For example, “children aged 2-4 who watch 1-2 hours of TV a day do not hit their parents more frequently than children who do not watch any TV.” For our study, we’ll consider our question to be “Individuals who have lived in the San Francisco Bay Area for 10-20 years and drink 2-4 cups of tap water daily do not have a greater incidence of breast cancer than the national average”. We conduct our study and gather data which will probably take a few years. Then we apply the proper statistics. If our study finds a difference, then we’ve disproven our null hypothesis, much hoopla will be made, and our findings will be published in the “Journal of Awesome Research”. If there’s no difference, then our null hypothesis still stands and our study will likely be published in the “Journal of Flibbity-Flooba”.
If we find no difference in the incidence of breast cancer in our study, have we “proven” that water is “safe”? No. All we’ve done is add data to the body of evidence that suggests that drinking water does not cause cancer and that it’s safe to drink it. As previously mentioned, nothing can be truly proven safe, even water; too much or too little of it can kill us, let alone if it is improperly purified. Yes, water can be considered dangerous: water-borne illnesses are one of the leading causes of death worldwide, water causes floods, and it can damage homes. But at the same time, we need water to survive and its intake in the proper amounts promotes health. Science has helped us define the harm that water can cause and the proper steps that we can take to ensure that harm is minimized.
Let’s go beyond our water analogy: here are a few other hypotheses along with a more narrow question of what will be tested:

  • Broad: The MMR vaccine does not cause autism. Narrow: There is no significant difference in the incidence of autism in caucasian children who have received Merck’s MMR vaccine in the San Jose Bay Area and children who are not vaccinated.
  • Broad: Eating transgenic crops does not harm the gut. Narrow: There is no significant difference in the relative abundance of bacterial species in the intestinal flora of pigs fed a diet consisting of 30% genetically modified Bt-corn for 30 days compared to a control diet.

Again, let’s say that you are unable to disprove your null hypothesis. Does that mean that you’ve proven that the MMR vaccine doesn’t cause autism? No. Have you proven that GMOs do not impact the bacteria in the gut? No. What you’ve done is add data to a body of evidence that suggests that the MMR vaccine doesn’t cause autism and that crops developed through biotechnology don’t cause harm. You’ve been able to demonstrate a relative lack of risk between the substance (the genetically engineered crop) and a control (the conventional crop) in the specific area examined.
Until someone comes up with a study showing that A causes B, then the null hypothesis is what we turn to: A does not cause B. Otherwise you could come up with any crazy hypothesis and people would have to “prove you wrong”. You could state that that earthquakes are caused by invisible dragons jumping at the same time and demand evidence showing that it’s not true. Or that wearing a watch causes carpal tunnel syndrome due to the radiation emitted by the watch. Or that computers leach dangerous toxins that cause brain tumors. That’s not the way it works. Dragons don’t cause earthquakes and computers don’t cause brain tumors, until you can prove otherwise. The onus is on the person making a claim to provide evidence supporting its existence. Therefore, if you claim that invisible dragons cause earthquakes, it is not my responsibility to “prove you wrong”. Rather, it is your responsibility to provide evidence demonstrating that these beings caused the earthquake. A similar analogy, known as Russell’s Teapot, was coined by the philosopher Bertrand Russell. To illustrate where the burden of proof rightfully belongs when someone makes an unfalsifiable claim, Russell laid out this example: “If I were to suggest that there is a teapot, too small to be detected by a telescope, orbiting around the Sun somewhere between the Earth and Mars, nobody would be able to disprove my assertion. But if I were to go on to say that, since my assertion cannot be disproven it should not be doubted either, then I should rightly be thought to be talking nonsense.” This example highlights how impossible it would be to “prove him wrong”; therefore, the burden of proof would lie with him, as he is the one making the claim.
Whenever someone makes an unfalsifiable claim, the burden of proof lies with the person making the claim. Without a credible hypothesis for harm, and after decades of study, the burden of proof for the people claiming that biotech crops could be causing autism or cancer, lies with those making these claims.  As Carl Sagan said: “Extraordinary claims, require extraordinary evidence.” Claiming that “we just don’t know enough” is a not hypothesis that can be tested and is not in itself evidence of harm: it’s just idle speculation.
The absence of single papers demonstrating safety is often used to invoke fear and doubt, and impossibility of proving a negative is often capitalized in anti-GMO rhetoric (this recent article by a medical doctor in the New York Daily Mail is a perfect example of such arguments): “Do we know that GMOs don’t cause cancer? Do we know that they don’t cause male infertility? etc.” Well, no… We don’t… But in the many feeding studies that have been conducted, there’s absolutely no evidence to suggest that it DOES cause cancer, there’s no logical mechanism proposed by which this might occur, and the null hypothesis still stands. You could virtually make the same argument about anything. “Do we know that eating pomegranates doesn’t case male pattern baldness? Do we know that typing on a keyboard doesn’t cause STDs?” No… We don’t… I don’t think anyone has ever done those studies. But strangely enough, no one has proposed a ban the use of keyboards until someone proves that typing on one doesn’t cause herpes, nor has anyone suggested that I should uproot the pomegranate tree in my backyard. Remembering that safety can never be proven and that we can only demonstrate a lack of relative risk can allow us to view such claims with skepticism. The null hypothesis also allows us to weed out superstitious nonsense from cohesive scientific arguments. Some of the conspiracy theories circulating right now include the idea that the ebola virus is man-made and that AIDS is not caused by HIV. We can stand against such harmful ideas by stating “show me the evidence suggesting that ebola IS man-made” or “here’s a plethora of data indicating that AIDS IS caused by HIV”.
When you ask for “proof that GMOs are safe” or ask for a paper that has this evidence, that is absolutely the wrong request. In fact, it’s a loaded question, whether the person asking realizes or not, the “proof” is impossible to provide, no matter the subject. Ask a specific question and then try to find the data showing that it DOES cause harm. Unfortunately, I can’t provide you with such data because I haven’t read a well-designed, well-executed, reproducible study demonstrating that GMOs have a negative health impact.
THIS is why scientists stress the number of studies that have examined genetically engineered crops. THIS is why scientists stress the statements made by reputable scientific institutions about GMOs. THIS is why meta-analyses and literature reviews are important. Because no single study proves safety: its the sum of the studies, the body of data, the totality of research that’s been done which suggests that the current GMOs on the market are safe relative to their conventionally bred counter-parts. By examining the body of data, scientists develop a consensus: the overwhelming majority of mainstream working scientists in the relevant field stop debating an issue because the direction that the evidence points has become clear. Although there are many matters on which a clear consensus has not yet emerged, on the topic of genetically engineered crops the consensus is that the current crops on the market place pose no greater risk to health than their non-GMO counterparts.
My last point is this: receiving funding for a study is very difficult, and the institutions that fund these grants want to see proposals that

  1. have a logical mechanism: in the context of this article, if a researcher wants to determine if a substance can cause harm, then the granting agency will want to know how that harm could potentially occur. In our exercise regarding the safety of water, we’d never get the money for our study unless we could outline a biological mechanism by which water could cause breast cancer.
  2. have a high likelihood of generating positive results or disproving the null hypothesis. Negative data or being unable to disprove your hypothesis doesn’t really build a career for a research scientist in the current academic system, nor does it validate the work of the granting agency. As a consequence, many researchers will not pursue a path where they don’t see fruitful results nor will granting agencies fund such research. Imagine working on a project where you don’t expect to make a difference, waste tax-payers’ money, and burn away your time. Why on earth would you start such a project? While it is possible that this approach will miss some harms that we did not understand, in a resource constrained world, it’s counter-productive to pursue every speculation whether it makes “sense” or not. It’s far more productive to pursue the ideas that make sense before worrying about things that don’t make sense.

Whether or not you agree with the system, this is what scientists in the public arena have to work with. Scientists do not want to waste their time and valuable resources on a study where they don’t expect to demonstrate anything new. Instead of recognizing this simple explanation, many chose to believe that research is being silenced or that scientists are being paid off. Very nearly none of the scientists working in the relevant fields think that there is any reason that long term feeding trials of transgenic crops will produce a demonstration of harm, yet many anti-GMO activists would choose to believe that such research is not being conducted because “Big-Ag” drives funding at academic institutions. Rather than acknowledging that the absence of studies examining a link between Round-Up Ready corn and Alzheimer’s is a result of the fact that experts in the field cannot envision a credible mechanism for such harm based on the evidence at hand, many would prefer to believe that it’s because “Big-Ag” is suppressing the data or that Monsanto will break scientists’ kneecaps if they publish results suggesting that GMOs can cause harm.
But if your definition of “safety” is a 5 year longitudinal study on 1000 rats examining a link between Bt-corn and gluten sensitivity, by all means: spend 10 years of your life in school earning less than minimum wage, and then try to find a granting agency that will fund your study based on whatever evidence and reasoning you have. Best of luck in your future career path!


  1. Genetically modified food controversies are disputes over the use of foods and other goods derived from genetically modified crops instead of conventional crops, and other uses of genetic engineering in food production. The dispute involves consumers, farmers, biotechnology companies, governmental regulators, non-governmental organizations, and scientists. The key areas of controversy related to genetically modified food (GMO food) are whether such food should be labeled, the role of government regulators, the objectivity of scientific research and publication, the effect of genetically modified crops on health and the environment, the effect on pesticide resistance, the impact of such crops for farmers, and the role of the crops in feeding the world population. Found this on wikipedia and compared with what you have on this blog. I believe soon all this doubts about GMO foods will be cleared..great article.

  2. While I agree with what you say and share in the frustration, I feel this article was written for “people like us” and that it could do without the sarcasm and slang (“sucks,” for example). This is why people don’t like academics; too much snarky.

  3. I don’t think we have a null hypothesis when we’re studying GMOs. I think we can pose lots of questions to study how this technology changes the food plant we’re engineering. And of course, if we choose to include environmental safety, we have lots more areas where we can do research. All plant breeding carries the risk of generating unwanted changes – including the creation of toxins we might not expect in that plant. This has happened in conventionally bred plants, which, based on level of risk, are less likely to present unanticipated changes. Research on GMOs has shown changes in gene expression, structure, metabolism – separate from the kinds of changes we might expect as the result of environmental influence. The food may have changes in nutrition that are considered acceptable by the developer and the government reviewer, but unacceptable to consumers – who have no way of knowing.
    Plus I don’t think safety is the absence of risk. We already know there are risks, and what people want to know is how we’re managing those. But when it comes to answering those questions, it’s hard to find out exactly how we are managing those risks. Because the industry is reluctant to share information about how it manages risk – and – the regulations we have now don’t ensure that unwanted changes will be “caught”. New traits are treated like food additives by the FDA. Maybe someone can direct us to the studies the industry does to make sure the product is truly equivalent (everything we want and nothing we don’t want) I think until that sort of analysis is done by independent bodies, people will continue to ask you to “prove GMOs are safe”.
    In these comments I link to example of studies which draw different conclusions on the same GMOs

  4. Hi Mlema,
    There are types of research where you don’t have a null hypothesis. Actually, for my doctoral thesis, I didn’t have a null hypothesis, because I wasn’t really testing anything. I had a working hypothesis, but not a null hypothesis. But when we test for harm, there is a null hypothesis. Yes, I agree: safety isn’t the complete absence of risk, but it’s the relative absence of risk. The risks that are present must be managed and in the example of water, we treat water with chlorine to manage risk of water-borne pathogens.
    Your comments on the two papers are interesting and I’ll have to look at them more closely. I’m not sure if you saw the piece I wrote on substantial equivalence? See: https://biofortified.org/2015/03/conventional-breeding-vs-transgenesis/

  5. I admit, I’m confused. Perhaps it’s the metaphysical arguments: dragons causing earthquakes and Russell’s teapot. Or changing the claim about water (H2O) to one about tap water. I don’t think the comparison of GMOs to H2O is a good one. Nor is the one about getting STDs from a keyboard or baldness from a pomegranate. Certainly it’s possible for a GMO to be created that would cause harm – and certainly that could find its way into our food supply, just like any new food. The level of risk just depends on how and what’s developed, and how it’s regulated.
    “A does not cause B” – Would that translate to: GMOs do not cause harm? I’m sure it would be possible to then make narrow statements to attempt to disprove that statement – although here I think it’s important to say that the biggest problem with making the broader statement is: every GMO is unique. It’s like saying: cars do not cause harm. So in that way, what you’re saying makes a lot of sense. But only because the other side of that coin says: you can’t prove GMOs are safe because there are so many things that can be wrong with them 😉
    “…if a researcher wants to determine if a substance can cause harm, then the granting agency will want to know how that harm could potentially occur. In our exercise regarding the safety of water, we’d never get the money for our study unless we could outline a biological mechanism by which water could cause breast cancer.”
    You seem to be suggesting that there’s no mechanism by which a genetically engineered food could cause health problems. What about engineering a corn to make Cry9C – that ended up in the human food supply? It seems we were lucky, but I think we could just as easily have been unlucky.
    Health and governmental organizations always qualify their statements on GMO safety. Like: ‘Current GMOs show no evidence of causing health problems’. The qualifiers often get lost when their general endorsements are used to defend/promote specific GE products. Also lost: the degree to which any such organization is beholden to the industry that develops the products. Most still agree: new GE products should be individually evaluated in a number of ways in order to assure safety (in as much as that’s possible). In fact, there’s actually a lot of debate over what sort of safety evaluations should be done and by whom – and how they should be tailored to various GE organisms.
    So, in my confusion, I’ll just say: I agree that no one can “prove that GMOs are safe”. But, I do think there are safety questions that have to be answered for every new GMO, and what those are should probably be based on the GMO itself. And as we do more complex engineering, those questions should evolve as well. A lot of what we’ve learned about genetic engineering has come from just doing it and then evaluating it. Not sure that’s the best way forward.
    This paper from David Schubert talks about some of the issues that need to be addressed when engineering nutritionally enhanced plants.
    Pro-industry advocates call this paper scaremongering and hand-waving. I’m just linking you to it so you can consider it for yourself as illustrating some examples of how GE can possibly cause harm.
    Thanks! I’ll look at your other post soon.

  6. I think you raise a lot of great points. I think that “GMOs are safe” or “GMOs cause harm” are way too broad. As I point out in the post, we need to focus on specific questions, rather than sweeping statements. So yes, part of the reason why we can’t say that anything is safe is because there are infinite questions that could be asked.
    There are mechanisms by which a genetically engineered food could cause health problems, and the reason why we conduct tests is to mitigate these risks. See this study as an example: http://www.ncbi.nlm.nih.gov/pubmed/8594427 Although this paper is often used by those who oppose GMOs as an example of how things can go wrong, it could just as easily be an example of how proper testing can mitigate the risks of transgenic crops.
    I had not seen the paper from David Schubert, and thank you for sharing that. It’s interesting, but it’s also a list of hypothetical things that could go wrong. I wrote about this in a different context on my personal blog here: http://frankenfoodfacts.blogspot.com/2014/03/review-of-gmo-myths-and-truths-part-1.html I think this is probably the most pertinent sentence: “As mentioned, the authors admit that we’ve gotten better at creating transgenic crop, but they omit that we’ve gotten astronomically better at detecting unintended consequences. Technologies such as whole genome sequencing and microarrays are used because of the whole “we don’t know what we don’t know” phenomenon. These technologies will allow you to analyze RNA and DNA so that you can identify mutations that you didn’t intend to make or RNA hybrids that you were unaware of. In a recent Q&A with the Arctic Apple company on GMO Skepti-Forum, Arctic Apple’s staff mentioned that they had the genome of their apple sequenced. All 750 million bases of it. And their conclusion was that there were no unintended mutations. So it’s not surprising that in an online search, I was able to find out that companies such as Monsanto and Dow Agro use these technologies as well to study GMOs.”
    A good section of Schubert’s paper is about the whole Tryptophan incident. I wrote about this a while back (http://frankenfoodfacts.blogspot.com/2013/11/irt-gm-food-supplement-caused-deadly.html). The NEJM paper that investigated the incident doesn’t mention how the contaminant was made. The manufacturer of the supplement made quite a few changes in their process in a very short time period, so finding root cause was not possible (http://www.nejm.org/doi/full/10.1056/NEJM199008093230601#t=article+Results).
    I also think that it’s important to keep in mind that traditional breeding methods could also generate allergens and novel proteins. Traditional breeding methods can also cause harm (the Lenape Potato is a classic example). So I don’t think that there’s anything inherently riskier in a GMO than a traditionally bred crop.

  7. Here’s the point: we now know that tiny amounts of altered metabolites can have major impacts on health. And they’re more likely to appear with certain types of GE. We do require allergenicity testing on a new trait – like the addition of 2S albumin to soybean mentioned in your 1996 study. But we don’t require testing that would reveal the kinds of inadvertent, unwanted results discussed by Schubert.
    “So I don’t think that there’s anything inherently riskier in a GMO than a traditionally bred crop.”
    Isn’t this the kind of sweeping statement we’ve decided we should avoid? Since we’ve already established that deleterious changes can occur, the risk is then determined by how well our regulations prevent those changes from reaching the market. If companies are doing the sort of exhaustive analysis you describe, why don’t we just require it and have independent regulators examine it?
    I don’t support a “stuff happens” approach to GMO safety.

  8. Nobody has to ‘prove GMOs are safe’, we just need to move the bar more in the direction of ‘safe’ as much as we can. We have a responsibility to ask better questions all the time, and not stick our heads in the sand, while human breast milk contaminants rise.

  9. No, I stand by that statement. There’s nothing in the process of making a GMO that is riskier than the process of making a traditionally bred crop. Both have risks, and one could argue that adding 1-2 genes has fewer unintended consequences than traditional breeding. The statement does not mean that deleterious changes cannot occur.
    I absolutely agree with you on the second part of your comment. I don’t like the “voluntary” testing that GMOs undergo. I think that this article from Grist outlines the issue very well: http://grist.org/food/the-gm-safety-dance-whats-rule-and-whats-real/ I think that there should be a mandatory set of tests, and that these will increase with the relative risk of the trait being introduced. For example, if someone wants to make a crop using the same Bt protein that’s already in corn, I don’t think that testing for allergenicity should be required or animal feeding studies. But I think that sequencing of the crop’s DNA, showing where it’s introduced and that there aren’t any unintended consequences, should be required. But if someone is introducing a protein into a crop for the first time, then feeding studies, allergenicity, etc should be required.

  10. I have one questions for Layla Parker-Katiraee — Do you eat genetically modified food, or do you eat organic food?

  11. Layla,
    Your quote: “There’s nothing in the process of making a GMO that is riskier than the process of making a traditionally bred crop.” might be correct, i’m not sure yet, however, the speed of the development of GMOs could mean that IF a risky development occurred it might crop up much quicker than in conventional breeding. And with even more experimental GMOs rapidly being developed, the risk of finding risks could then increase per unit of time compared to conventional breeding. However, it would also mean that any beneficial characteristics could increase too. IMHO

  12. I think all you have to do, is hammer home that nearly all foods on the market have been altered many times by accelerated mutation breeding, using x-ray, gamma, and chemical mutagens, and none of this has ever been examined by government regulatory bodies.
    If you mention this to an anti-GE believer, they try to excuse mutation breeding, without even knowing what it is. Then they forget about it, and go about attacking “corporations”.
    Having said that, I don’t believe that making crops glyphosate resistant, and adding copyright mechanisms is a good idea, if you want to placate an anti-corporate public.

  13. In my experience, I have seen several different reactions to anti-GMO individuals being told about mutagenesis and all that. Some deny that it is true, or even deny that it is allowed in organic agriculture. Others decide that mutagenesis must also be labeled or banned. So far, none have said that it made them feel better about GMOs.
    However, several of us have noticed that there is a basic misunderstanding about the need for genetic changes to food through breeding and/or genetic engineering. I find the most effective approach for an open-minded audience is to talk about why we need to change the genetics of our crops, and then I talk about some of the different ways of doing that. People need to be convinced of the need for these changes in general.

  14. Ray, why do you say that harms would crop up quicker with genetic engineering than in non-GE breeding? The research that I am familiar with indicates that GE causes fewer unintended consequences than breeding when you are trying to move an individual trait from one variety to another, or to generate new traits.

  15. Karl, and Chris,
    Yes, but my point was with the ‘per/unit of time’ potential appearance of changes within GE AG compared with the much slower conventional breeding. GE might cause fewer unintended consequences, but since GE is expanding at such a rapid rate, a larger total number of unintended consequences could still accumulate at a faster rate than the slower development of the conventional breeding. Not a big deal… unless it is a big deal. Just means that GE AG has a challenge to keep those unintended consequences from becoming a big deal. Far wider, faster, dispersal around the globe of GE crops means potential far wider spread of an such unintended consequences before adequate corrective action could be made. Larger populations could be affected more quickly that with conventional breeding. Just saying.IMHO

  16. Hi Emily,
    I feed my family (including my 3 year old son) both. I try to buy fruits and veggies that are in season and are from California (since that’s where we live), and I just buy whatever’s cheapest. Lately, that seems to breakdown as:
    -meat/eggs/dairy: always conventional
    -fruits and veggies: mostly conventional, except berries which are sometimes cheaper when organic.
    -dry goods: generally conventional, except for my kids’ snacks which are cheaper at Costco as organics. The Kirkland brand has some very good deals on childrens’ organic snacks.

  17. Why do you think that speed of development of GMOs is faster…
    Monsanto, for instance, releases approximately 100 new corn hybrids every year into the North American market. They release, optimistically, one trait a year, maybe one every two to three.
    New hybrids can hit the market in as few as two to three years, new lines probably take 5 or 6 (new hybrids made using established lines don’t require as much testing, new lines have to be proven winners before consideration as commercial material)
    A new trait will take approximately a decade to reach the market.

  18. Hi Layla, We are very far from the kind of mandatory set of tests you describe. I appreciated the Grist article, and will link to this report referenced in that article. Our regulations haven’t changed since their inception.
    Holes in the Biotech Safety Net
    It’s not just about the relative risk of the trait. I think the statement “There’s nothing in the process of making a GMO that is riskier than the process of making a traditionally bred crop.” is still too broad. Which GMO? what process? Which traditionally bred crop? This graphic illustrates “Relative likelihood of unintended genetic effects associated with various methods of plant genetic modification.”
    I think this is about: what possible harm can be created by any one individual GMO – and – does our current regulatory system ensure that that harm will not happen? In our current GMOs it doesn’t seem that the risk of harm is too great. That’s for more than one reason, one being that people aren’t generally exposed to the foodstuff in a way that might cause harm if there were any. And the engineering of herbicide tolerance isn’t one that would be prone to creating the kinds of changes that might have a health effect. Also, because bt is a pesticide, the EPA has required its own testing. However, even so, if there were harmful changes in any of the many dozens of GMOs we’ve commercialized, we would have no way of knowing. This becomes more of an issue as we begin to tinker with nutrition.

  19. I think this is about whether or not you believe it’s possible for genetic engineering to produce changes in structure/metabolism that would lead to negative health effects in humans, and whether or not our regulatory system would “catch” those.

  20. Mlema, most of us recognize that gene transfer, even if done exactly as intended, can have unknown and undesirable metabolic effects. We also recognize that no testing method or regulatory regime can catch every possible unanticipated trait.
    Where we differ from the anti-GMO groups is that we don’t believe that the biotechnology-based transformations are ESPECIALLY risky in comparison to many other breeding technologies, and the reasons for our belief are overwhelmingly sound.
    Surely you would agree that gene changes accomplished by exposure of the organism to gamma rays are MORE LIKELY to cause unanticipated metabolic changes. Almost as surely, you would agree that induced polyploidy is MORE LIKELY to cause unanticipated metabolic changes. Possibly you would even agree that even non-genetic changes, such as growing conditions, can change metabolism in unanticipated ways that might cause harm. The question, then, is “Why does biotechnology get treated so suspiciously while these other issues are essentially ignored by the anti-GMO movement?”
    Sometimes those anti-GMO suspicions are presented dishonestly. (I’m not talking about the blatant dishonesty aimed at fools, such as the suicide seeds or the wild animals who avoid GMO crops.) For example, we often read that the process of gene transfer is imprecise and can make gene changes beyond the insertion of a desired gene, such as when the inserted gene lands in the middle of another gene. But that’s irrelevant since after the insertion event, we can analyze the genome to see precisely how it was changed. Why do we need to waste time debunking these dishonest claims?
    Another issue is that while no testing or regulatory protocol can efficiently detect UNANTICIPATED effects, we can do very well in testing for ANTICIPATED effects. In the case of a GMO, there’s a very definite set of anticipated effects which suggest tests – for example, we can test whether the new protein is an allergen, or whether the promoter gene is turning the desired gene on (or off) in the anticipated way. With many other breeding methods we have ONLY unanticipated effects and we have ONLY HOPE that some of them are favorable traits. We have no clue about how to test new non-GMO crops for anything.

  21. Charles, you put things a bit more bluntly than I may have done, but I agree that the level of scrutiny focused on plant and animal recombinant DNA technology compared to the total lack of scrutiny for all other genetic changes that present far more potential for unintended changes makes no sense.

  22. Ewan – I wonder if you could explain that genetic engineering, at least for corn, is at its essence a means for introducing traits into a breeding program that are introgressed into existing varieties pretty much as any other trait is regardless of the source of of the trait.
    People have, I think, the mistaken mental model that ge means that we take a genome, do some funky laboratory manipulations in a petri dish, and then the resulting glob we grow out into an organism that yeah resembles corn but is really some synthetic version of corn. Then we take that organism and replicate it until we have commercial quantitides of seed, bag it up, and sell it to farmers. This new synthetic organism replaces all the hundreds of varieties of corn that preceded it and we must just throw all the old varieties out and are left with this one, genetically uniform synthetic corn replica.
    It is my understanding that what actually happens is that yes we do accomplish a horizontal gene transfer of gene X, utilizing a a naturally occurring process, i.e.agrobacterium infection, under laboratory controlled conditions, into the genome of a host corn cell. We then allow that cell to develop into a corn plant with gene X. We then transfer gene X into the existing varieties by the familiar methods of crossbreeding these varieties with the host plant contains gene X.. With several iterations of backcrossing, we arrive at the original existing varieties but with the addition of gene X.
    Now, let’s say we find a variety of corn growing in Mexico that has a desirable gene, let’s call it gene Y. To transfer that trait to our existing varieties, we cross that Mexican variety into our existing varieties via crossbreeding, and with several iterations of backcrossing, our existing varieties now contain gene Y. Notice that we didn’t just take the Mexican variety, grow commercial quantities of it, bag the seed and sell it to farmers, and throw away all the hundreds of old seed varieties.
    Third example. We expose a a corn plant to radiation resulting in a mutation in the genome that is a novel gene, gene Z. Again, we transfer gene Z into our existing varieties by crossing the mutated plant now contains gene Z with the preexisting varieties, and with several iterations of backcrossing, arrive at the original existing varieties but now containing gene Z.
    In all cases, we did not abandon all of the diversity of genetics preexisting in the hundreds of corn varieties, we just added new genes on top of the genetic diversity represented in those varieties. And we accomplished the actual final transfer of the novel gene into our preexisting corn varieties by crossbreeding. In essence, genetic engineering, just like mutagenisis, in effect allows us to expand the genetic pool available to be accessed by and introduced into crop breeding programs beyond the confines of the gene pool available within that crop species.

  23. As a lay observer, I find this piece delightfully informative. The whole “null hypothesis” thing has confused me, but now I can say I understand it better. Many, many thanks.

  24. Charles, I get the feeling that you’re exasperated with anti-GMO groups and would like me to explain why they say what they say. But I can only speak for myself.
    Risk is relative. That’s why I’ve linked to the NAS report (above). It illustrates the “Relative likelihood of unintended genetic effects associated with various methods of plant genetic modification”. Of course, genetic effects aren’t necessarily concerning. What is the significance of the genetic effect to human health? – that’s the question. I agree with some of the comparisons you’ve made between various kinds of plant development, but not all. Same on the environment. I’ve already linked to another comment I made on this site that then links to these studies, but I’ll link strait away here (these are two studies that examine MON810, and compare it to similar varieties/isogenic parent in the field).
    The first finds “…that MON810 and comparable non-GM varieties are equivalent except for the introduced character.”:
    “Gene expression profiles of MON810 and comparable non-GM maize varieties cultured in the field are more similar than are those of conventional lines”
    “…no sequence was found to be differentially regulated in the two variety pairs grown in the field. The differential expression patterns observed between in vitro and field culture were similar between MON810 and comparable varieties, with higher divergence between the two conventional varieties.”
    The second finds protein changes apparently due to the engineering:
    Comparative proteomic analysis of genetically modified maize grown under different agroecosystems conditions in Brazil
    “This study observes that although differences in gene expression occur due to environmental conditions and show changes between parent, transgenic and other non-transgenic varieties, those changes can be isolated. And that further comparative analysis reveals that 32 proteins are differently expressed between MON810 and it’s isogenic parent, separate from environmental causes.”
    So, what is the significance of differently expressed proteins? Again, there may be no significance. What aspect of our regulations would ensure that these differently expressed proteins were safe?
    My other comments and links explain pretty thoroughly where I stand on safety and regulations. In order to sway my opinions on these things, you’d have to reply to the concerns raised by the scientists whose writing I’ve linked to.
    “..after the insertion event, we can analyze the genome to see precisely how it was changed”
    Who decides what level of change is acceptable? How is the significance of these changes determined? There would need to be some kind of assessment of changes in the final product in order to determine whether or not there might be a problem. Our regulations don’t require this, and although I would suspect that the industry does it as part of development in certain cases, there’s no transparency. We’re growing GMOs that haven’t been analyzed in this way. Right now, with herbicide tolerance and bt being the majority of GMOs, concerns are probably minimal. But the industry is moving into more complex engineering, and also engineering old traits into foods that will be directly consumed – like bt eggplant. Every event is unique and safety will become more important.
    Regarding testing new non-GMO crops – I think that would be done the same way we should be testing GMOs – by utilizing the best methodology we have for analyzing the composition of the plant and identifying problematic changes. The data is growing but we don’t always know what it means. So, again, it’s about whether or not you believe it’s possible for genetic engineering (or any breeding) to produce changes in structure/metabolism that would lead to negative health effects in humans, and whether or not our regulatory system would “catch” those. I gather that you don’t believe that it’s any more possible for transgenics to produce deleterious changes in our food than it is for any other kind of plant, and maybe even less so. I don’t mean to be confusing, but in some cases I’d agree, and in others not. There are just too many factors to allow for a generalization about GMO safety.

  25. Dr. Bodnar: “…the level of scrutiny focused on plant and animal recombinant DNA technology compared to the total lack of scrutiny for all other genetic changes that present far more potential for unintended changes makes no sense.”
    Anastasia, when you say “scrutiny” – are you talking about regulatory requirements? Or are you talking about public attention?
    If you’re talking about regulations, what is it that you believe is required of developers of transgenic plants that should NOT be required?
    What are you referring to when you say “all other genetic changes that present far more potential for unintended changes”? Are you referring to mutagenesis? Do you believe it should be regulated more? Or are you suggesting transgenics should be regulated less? What regulations -exactly- should be added or done away with?
    Thank you for your answers.

  26. Ewan, I wouldn’t mind having you explain that opinion as it relates to safety issues and regulation.

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