toxicity graphic edit

by Megan L. Norris

Summary: As the prevalence of genetically modified organisms (GMOs) continues to rise, there has been an increasing public interest for information concerning the safety of these products. Concerns generally focus on how the GMO may affect the environment or how it may affect the consumer. One specific concern is the possibility for GMOs to negatively affect human health. This could result from differences in nutritional content, allergic response, or undesired side effects such as toxicity, organ damage, or gene transfer. To address these concerns, there have been over 100 research studies comparing the effects of traditional food to genetically modified food, the results of which have been reviewed in various journals [1], [2]. How these results affect regulation can be found through The Center for Environmental Risk Assessment, which hosts a GM Crop Database that can be searched by the public to find GMO crop history, style of modification, and regulation across the world [3]. Though knowing who to trust and what to believe regarding this topic is an ongoing battle, major health groups, including the American Medical Association and World Health Organization, have concluded from the research of independent groups worldwide that genetically modified foods are safe for consumers [4]. Regarding toxicity, this includes any dangers related to organ health, mutations, pregnancy and offspring, and potential for transfer of genes to the consumer.

GMO toxicity: fears and scientific analysis

After genetically modified foods were introduced in the United States a few decades ago, people independently reported toxic effects caused by GMOs. One example is an anti-GMO advocacy group called the Institute for Responsible Technology (IRT), which reported that rats fed a diet containing a GMO potato had virtually every organ system adversely affected after just ten days of feeding [5]. The IRT stated that the toxicity was the result of genetic modification techniques and not a specific case for that particular potato. They claimed the process of making the GMO caused it to be toxic and thus all GMOs were high risk for toxicity.

Scientists across the U.S. and the rest of the world have sought to rigorously test the assertions of the IRT and others to uncover any possible toxicity caused by GMOs. To this end, many different types of modifications in various crops have been tested, and the studies have found no evidence that GMOs cause organ toxicity or other adverse health effects. An example of this research is a study carried out on a type of GMO potato that was genetically modified to contain the bar gene. The product of the bar gene is an enzyme that can detoxify herbicides and thus protects the potato from herbicidal treatment.

In order to see if this GMO potato would have adverse effects on consumer health like those claimed by the IRT, a group of scientists at the National Institute of Toxicological Research in Seoul, Korea fed rats diets containing either GMO potato or non-GMO potato [6]. For each diet, they tracked male and female rats. To carefully analyze the rats’ health, a histopathological examination of tissues and organs was conducted after the rats died. Histopathology is the examination of organs for disease at the microscopic level (think pathologist doing a biopsy). Histopathological examinations of the reproductive organs, liver, kidneys, and spleen showed no differences between GMO-eating and non-GMO-eating animals.

Three years earlier, a separate group had found the same results for a GMO tomato and a GMO sweet pepper [7]. These researchers had split rats into four diet groups: non-GMO tomato, GMO tomato, non-GMO sweet pepper, and GMO sweet pepper. They fed the rats over 7,000 times the average human daily consumption of either GMO or non-GMO tomato or sweet pepper for 30 days and monitored their overall health. Finally, they carried out histopathology and again found no differences in the stomach, liver, heart, kidney, spleen, or reproductive organs of GMO versus non-GMO fed rats. Despite massive ingestion of GMO potato, tomato, or sweet pepper, these studies demonstrated no differences in the vitality or health of the animals, even at the microscopic level.

Experiments like these on humans would be completely unethical. Fortunately, prior to these studies years of work have demonstrated that rodents, like mice and rats, are acceptable models for humans, meaning rodent responses to drugs, chemicals, and foods can predict human response. Rat feeding studies like these, in which rats are fed a potential toxic item and monitored for adverse effects, are considered both specific and sensitive for monitoring toxicity of foods and widely used in the food regulation industry [1].

The test of time: GMOs and their effect on our offspring

Although scientists have been able to demonstrate that GMOs are not toxic to the animals that eat them, as described above and elsewhere, what about side effects being passed on to our next generations?

To discern whether GMO crops affect fertility or embryos during gestation, a group from South Dakota State University again turned to studies on rats. In this case, the rats were eating a type of GMO corn, more commonly known as Bt corn. Bt stands for Bacillus thuringiensis, a microbe that produces insecticidal endotoxin and has been used as a topical pesticide against insects since 1961 (see this article). To allow corn to directly generate this endotoxin, scientists introduced a gene from Bt into the genetic material (DNA) of corn.

To address buildup of toxicity over time, this group monitored the GMO-eating rats not only for the lifetime of one generation, but also three additional generations. For each generation, they tracked the fertility of parents and compared the health of the embryos from parents that ate Bt corn to those with parents that did not [8]. Toxic effects can arise in many places and in many ways, but some organs are more susceptible to damage than others, and monitoring them is a good readout for other difficult-to-see effects. Testes are considered a particularly sensitive organ for toxicity tests because of the high degree of cell divisions and thus high susceptibility to cellular or molecular toxins.  To examine the affect of Bt corn on testicular health, the researchers tracked testicular development in fetal, postnatal, pubertal, and adult rats for all four generations. The group found no change in testicular health or litter sizes in any generation. Likewise, ingestion by pregnant mothers had no effect on fetal, postnatal, pubertal, or adult testicular development of her offspring.

Other groups have monitored toxicity over time as well. For example, the group studying the bar GMO potato also wanted to see if organs and reproductive health were sensitive to GMOs over long exposure times [5]. To do this, they examined the fertility and gestation periods of GMO-eating mothers compared to non-GMO-eating mothers for five generations. They tracked animal body weight, bone, eye, and thymus development, and general retardation. Like the studies on Bt corn, in all cases, they found no significant differences between the GMO potato and non-GMO potato diets, suggesting that there is no buildup or inheritance of toxicity, even over multiple generations.

Figure 1. Work from independent researchers has investigated various aspects of GMO safety, especially concerning consumer health and toxicity.

Can GMOs change our genes?

Concern has also surrounded the idea that genetically modified DNA would be unstable, causing damage (via unintentional mutations) not only to the crop, but also to whomever would consume it. Mutations in DNA are closely tied to cancer and other diseases, and thus mutagenic substances can have dire effects on human health. The creation of mutations, called mutagenesis, can be measured and compared to known mutation-causing agents and known safe compounds, allowing researchers to determine whether drugs, chemicals, and foods cause increased mutation rates. There are a variety of ways to measure mutagenicity, but the most traditional method is a process pioneered by Bruce Ames at the University of California in Berkeley. His method, now called the Ames test in his honor, is able to track increased rates of mutations in a living thing in response to some substance, like a chemical or food.

To directly test the ability of a GMO to cause mutations, a research group from the National Laboratory of Protein Engineering and Plant Genetic Engineering in Beijing, China applied the Ames test to GMO tomatoes and GMO corn [8]. GMO tomatoes and corn express the viral coat protein of cucumber mosaic virus (CMV). Expression of this coat protein confers resistance to CMV, which is the most broadly infectious virus of any known plant virus, thought to infect over 1,200 plant species from vegetable crops to ornamentals. The results of the Ames test demonstrated no relationship between GMO tomatoes or corn and mutations. They repeated their analysis using two additional methods for analyzing mutagenicity in mice and got the same result, allowing them to conclude that genetically modified DNA did not cause increased mutations in consumers. The modified DNA, like unmodified DNA, was not mutagenic.

Mutagenicity aside, there are also concerns surrounding the ability of the modified DNA to transfer to the DNA of whomever eats it or have other toxic side effects. Depending on the degree of processing of their foods, a given person will ingest between 0.1 and 1 g of DNA each day [9]; as such, DNA itself is regarded as safe by the FDA [10]. To determine if the DNA from GMO crops is as safe to consume as the DNA from traditional food sources, the International Life Sciences Institute reviewed the chemical characteristics, susceptibility to degradation, metabolic fate and allergenicity of GMO-DNA and found that, in all cases, GMO-DNA was completely indistinguishable from traditional DNA, and thus is no more likely to transfer to or be toxic to a human [9]. Consistent with this, the researchers working on the GMO potato attempted to isolate the bar gene from their GMO eating rats. Despite 5 generations of exposure to and ingestion of the GMO, the researchers were unable to detect the gene in the rats’ DNA [5].

A strong argument for GMO health safety

After more than 20 years of monitoring by countries and researchers around the world, many of the suspicions surrounding the effects of GMOs on organ health, our offspring, and our DNA have been addressed and tested (Figure 1). In the data discussed above, alongside many more studies not mentioned here, GMOs have been found to exhibit no toxicity, in one generation or across many. Though each new product will require careful analysis and assessment of safety, it appears that GMOs as a class are no more likely to be harmful than traditionally bred and grown food sources.

Megan L. Norris is a Ph.D. candidate in the Molecular, Cellular and Organismal Biology Program at Harvard University.

This article is part of the August 2015 Special Edition, Genetically Modified Organisms and Our Food.

References

1. European Food Safety Authority GMO Panel Working Group on Animal Feeding Trials. “Safety and nutritional assessment of GM plants and derived food and feed: the role of animal feeding trials.,” Food Chem. Toxicol., vol. 46 Suppl 1, pp. S2–70, Mar. 2008
2. G. Flachowsky, A. Chesson, and K. Aulrich, “Animal nutrition with feeds from genetically modified plants.,” Arch. Anim. Nutr., vol. 59, no. 1, pp. 1–40, 2005.
3. Cera-gmc.org, ‘Welcome to the Center for Environmental Risk Assessment | CERA’, 2015. [Online]. Available: http://www.cera-gmc.org. [Accessed: 11- Jul- 2015].
4. Tamar Haspel. “Genetically modified foods: What is and isn’t true”. Washington Post. October 15, 2013.
5. G. S. Rhee, D. H. Cho, Y. H. Won, J. H. Seok, S. S. Kim, S. J. Kwack, R. Da Lee, S. Y. Chae, J. W. Kim, B. M. Lee, K. L. Park, and K. S. Choi, “Multigeneration reproductive and developmental toxicity study of bar gene inserted into genetically modified potato on rats.,” J. Toxicol. Environ. Health. A, vol. 68, no. 23–24, pp. 2263–2276, 2005.
6. Jeffrey Smith. “GM Potatoes Damaged Rats.” Genetic Roulette, Section I: Documented Health Risks.
7. Z. L. Chen, H. Gu, Y. Li, Y. Su, P. Wu, Z. Jiang, X. Ming, J. Tian, N. Pan, and L. J. Qu, “Safety assessment for genetically modified sweet pepper and tomato,” Toxicology, vol. 188, no. 2–3, pp. 297–307, 2003.
8. D. G. Brake, R. Thaler, and D. P. Evenson, “Evaluation of Bt (Bacillus thuringiensis) Corn on Mouse Testicular Development by Dual Parameter Flow Cytometry,” J. Agric. Food Chem., vol. 52, no. 7, pp. 2097–2102, 2004.
9. D. A. Jonas, I. Elmadfa, K. H. Engel, K. J. Heller, G. Kozianowski, a. König, D. Müller, J. F. Narbonne, W. Wackernagel, and J. Kleiner, “Safety considerations of DNA in food,” Ann. Nutr. Metab., vol. 45, no. 6, pp. 235–254, 2001.
10. FDA: Guidance to Industry for Foods Derived from New Plant Varieties, Section V (C).

24 thoughts on “Will GMOs Hurt My Body? The Public’s Concerns and How Scientists Have Addressed Them

  1. Not sure if I missed the answer to this here: is there a good explanation for the mentioned toxicity reports from the early anti-GMO research? Or does one have to just weigh the evidence of the body of work that contradicts them, as done here?

    1. Good question Brian, and this is one of the greatest hurdles to understanding the truth and falsehoods surrounding the topic.

      There are a few issues:
      1.) Many of the “studies” citing GMO toxicity are not actual scientific studies, but anecdotes experienced by someone, almost always not in a research setting. However these are often referred to in blogs or articles as “studies”

      2.) In the case of a peer-reviewed study finding GMOs to be toxic, like the toxic-potato I mention here, it has repeatedly turned out that the work was flawed, poorly carried out and rejected by the scientific community for being bad science. Often a quick google search will reveal this.

      3.) The best way, and admittedly most time-consuming, to discern the truth is just as you said, be informed of all the experiments, their quality, and weigh the results. That is what I have attempted to do here, and it turns out that when only rigorous experiments are examined, they are actually all in agreement. No acceptable scientific study has yet found toxic effects from a GMO.

      1. Wish I had seen this in 2015. Megan, unless I missed it, there was no mention of other ‘organs’ such as the gut. Not the stomach- but the gut..the colon. In your research did you come across widely published scientific proof where a University in California found that a percentage of school-aged children had GMO’s actually in the gut of the child…and I don’t mean in some GMO food the child had consumed, I mean actually adhered in the lining of the gut? You might want to talk with specialists in the area of colorectal surgery. Ask them if they are finding that more and more people under the age of 19 are suddenly popping up with gut problems so horrible (as in a destroyed colon- the entire colon) that the entire gut can not be treated due to the fact that by the time the ‘problem’ manifests to the point of bleeding, it is too late and the entire colon has to be removed or it will burst and kill the individual. There is no margin, no years of gut problems such as colitis or even Chrones- just a sudden need to remove a colon that looks like raw hamburger. This is exactly what my son’s colorectal surgeon said to us….and among his colleagues, one suspect is the consumption of GMO foods. In fact, they have find no other reason thus far. My son went from 185 to 120 six weeks later. He had 4 surgeries and nearly died twice and his heart stopped once on the table- these events were due to the condition he was in. He was robbed of 1 1/2 years of his life due to the surgeries. His hair still has not grown back (3 years later) and at this point he is 21 years old. Not a very picture, is it? I believe one mistake you made is that you did not look for (or find) research done on the ENTIRE body. It appears the information you found was for most organs but certainly not all. You’re young, you’ll learn, but in the mean time don’t lead people down a path pointing to the ‘safety’ of GMO’s. I’m not saying GMO’s are or are not safe, but I am saying at this point the question is ‘WHY’? Why eat something that isn’t necessary to eat (organics can be found and are coming down in price), why purposely eat something that you know has been grown at least with pesticides sprayed on it? What’s the reason…why would people even *want* to do that? It certainly doesn’t taste better, and the ground isn’t allowed to rest using GMO seeds, nor does the GMO (or what’s sprayed on it) nourish the ground…so WHY?

        1. Hi! Can you provide the source from the “widely published scientific proof” from “a University in California” that you mentioned? I would love to read it and maybe even write a follow up to this article about it. Thanks!

          Also–FYI there are plenty of benefits of GMOs that answer your question of why we allow them. Including reducing pesticides when compared to non-GMO conventional agriculture, reducing tilling, and hopefully in the future making crops more resistant to environmental disaster and less destructive to the planet. I’d recommend checking out the rest of our special edition (see link at the bottom of this page)!

          1. Plants aren’t destructive to the planet, it is the way they are raised that promotes destruction. Agribusinesses who unsustainably farm, and overuse pesticides have lead to the requirement for GMO crops and they have largely contributed to environmental damage. It’s a never ending cycle and GMO products are not the solution, merely a quick fix. If natural alternatives were promoted, farms were treated like organisms and not businesses, and sustainable methods were priority this discussion would not be necessary. I like my food from the earth, with its DNA pure, the way it was intended to be.

            Also, if a crop is altered to produce its own pesticides, and the claim is that with GMO crops you are now spraying less pesticides doesn’t the total pesticide count, whether produced internally or applied externally, still add up to non-GMO conventional agriculture?

          2. First, farming itself can be destructive to the plant! Tilling (both organic and conventional!) can cause fertilizer runoff into our water sources, conventional agriculture still uses pesticides. Plants themselves aren’t usually bad for the environment, but growing them in huge quantities like we do to be able to feed the world’s ever-growing population can be. I’m not saying GMOs are perfect. They have their environmental flaws, like the creation of super weeds (see our article on glyphosphate resistant crops in this issue). I’m just saying that GMOs CAN have benefits ESPECIALLY if we learn from our mistakes with first generation GMOs and do better to fix their flaws next time. The population is growing, climate change is happening, and science–specifically genetic engineering–can help us grow food more sustainably in light of these things. Did you hear about the GMO rice that produces 43% more grain and emits 97% less methane (http://sitn.hms.harvard.edu/flash/2015/feeding-the-world/)? Therefore helping to both feed more people AND have less environmental impact! This kind of thing speaks to the potential of genetic engineering and the kind of progress that people are stopping by outright rejecting all GMO technology. Yes GMOs we have now have their issues, but genetic engineering is NOT inherently bad.

            Also, GR GMOs don’t produce pesticide. They are resistant to pesticide. One form of GMOs produces insecticide (Bt–we have an article on that in this edition, too, if you’re interested!), but it’s actually the same insecticide that is used by organic farmers (http://sitn.hms.harvard.edu/flash/2015/insecticidal-plants/), and I believe there is evidence that the consumer has less exposure to the insecticide in the GM version than when it’s applied directly to plants. A study of these two types of crops did find that these crops allowed for a 36.9% reduction in pesticide use (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0111629)! Also, glypohsophate, which is used on GR crops is toxic, but less toxic than other pesticides used on conventional crops (see our article on pesticides).

            Given that there is little to no evidence of health impacts of eating GMOs (as in this article) and a potential to help solve a major problem our world faces in the future (climate change, feeding a growing population), I just think that we should give GMOs the chance to help us, as long as they’re properly regulated and researched.

    2. The short answer is: the toxic-potato study had design flaws that didn’t allow them to draw any conclusions from their work. One aspect was that their control potato was not equivalent in nutritional value to their GMO potato, meaning a difference in health could just as likely be due to malnutrition.

      1. It amazes me how you consider “your science” the only “right science” and how linear is your way of thinking. Nothing in biology is as simple as you pretend to be and there are many other factors that influence the number and quality of toxicity studies on GMOs. Have you considered ‘funding’ and ‘conflict of interest’ at all in your analysis? I would love to hear from you what exactly is “bad science” and what is “good science”. This is a million dollar question and you would solve all the issues for the scientific community!

        Let me also remind you that 85% of all GMOs are herbicide tolerant and that they were designed to accumulate herbicides and thus going into the food and feed chains.In addition, most of all new GM plants have multiple trait and there is almost no studies that test multiple Bt toxins and multiple herbicides together. This is recognized by EFSA and the scientific community as a knowledge gap. There is a need to study real case scenarios, the food we eat 🙂

        1. Hi Sarah! Thanks for reading! First of all, a lot of GMOs are herbicide tolerant, as you said, but they are not designed to “accumulate herbicide”, but rather resist herbicide. Yes–this can lead to the use of more pesticides on these crops, but the health effects of that on the consumer are unclear. Also, Bt crops actually DECREASE the use of chemical insecticide AND have less Bt (the most common organic insecticide) than organic crops! (See http://sitn.hms.harvard.edu/flash/2015/gmos-and-pesticides/, http://sitn.hms.harvard.edu/flash/2015/insecticidal-plants/, and http://sitn.hms.harvard.edu/flash/2015/roundup-ready-crops/ for more info!). Also, plenty (if not all) of the studies cited here are funded by government agencies in multiple countries, as is most basic scientific research, so there should be no conflict of interest. You’re right that most GMOs have stacked traits to be GR and express Bt, and it might be worth testing those two traits together if it hasn’t been done already (I’ll let Megan answer that). However, what is abundantly clear is that the actual process of genetic modification does not make a crop bad for our health–it’s all about what you modify! It furthermore seems unlikely given the current data that any of the GM crops we eat now are dangerous to our health.

          Finally, addressing your first paragraph, many of us at SITN are biologists, and we are aware the biology is complicated! We also believe in trusting data. I am interested in seeing all sides of this issue–if you know of other studies that show that GMOs are dangerous to our health, please let me know! I am always willing to change my mind with new evidence. Untrustworthy science is that without controls that did not go through a peer review process and cannot be replicated (like the IRT study), trustworthy or “good” science is the opposite.

  2. I think it is premature to make blanket statements about the safety of GMOs based on the research to date. Some potential holes in the analysis of prior research.

    1. Mice studies are not the equivalent of a double-bind long term human study. Of course you are right that this can not be done but the assertion that mice studies are enough to “prove” safety is not enough in my opinion

    2. Your review of literature show at best that the technique of gene splicing in and of itself is not harmful but this not mean that dangerous & harmful products can be created with gene splicing. Given the infinite permutations of genes that can be combined in the lab it will be only a matter of time that a particular combination will have emergent properties that will be devastating consequences that were not foreseen. With anything, as time goes on business and scientists become lax over time. Mishaps in the Nuclear power industry are a prime example of this.

    3. Lack of studies on population outliers. Sure many products may be safe for the general population but can have very severe consequences for certain segments of the population. Have there been studies looking at particular GMO products against all types of test subjects? Some variables would be pregnant, immune comprised, infant, etc.

    The reason I bring these issues up is that I have two sons. One with a fructose intolerance issue and another with severe allergic GI issues. Per a multitude of studies, the human population is seeing a dramatic rise in allergenic & gastrointestinal ailments in the last 25 years that parallels the introduction of GMO foods. This correlation alone of course does not prove causality but where there is smoke, science must take the time to identify the source of the fire.

    1. That sounds like:
      1. My goalpost is unattainable, and you haven’t reached it yet.
      You mentioned something which cannot be done should be done in order to garner proof. You also are the first person to mention “prove” on this page.

      2. Just because bad things can result from something, does not mean that thing is inherently harmful to you. Nearly everything you do with a positive outcome, has a negative consequence.

      3. Please see the argument written above in the original piece.

      Sometimes there is no fire. Sometimes there is just more understanding. Sometimes, we get better at catching irregularities as time passes. Correlation most certainly does not prove causation, but more-so, correlation doesn’t prove causation especially when it directly contradicts what we already know to be most likely.

  3. There are some additional things that bother me about GMO’s. DNA and the interplay of the various genes is phenomenally complex. Without even making any alterations in a genome there are many things we do not fully understand about how it all works- what synergies exist, what sequences are key for subsequent sequences to operate successfully, etc. Until I feel confident that we understand more about the complexities of the existing genomes WHEN they are operating within living ecosystems, I do not feel comfortable throwing a wrench into the works. It has taken millions of years for evolution to fine tune these systems- both ours and the plants we are dependent on for food- and there are millions of variables affecting both our internal and external environments. GMO’s feel way too much like playing God. I would rather choose the humbler path of following nature’s lead than the arrogant path, (the one that got us kicked out of the garden of Eden and which is leading us to ruin our second Eden), of tinkering with potentially life threatening technologies .

    My second major issue with GMO’s is that most are “owned” by one major corporation, Monsanto, and the rest are owned by only a few others. Monsanto would have us believe they are interested in GMO’s because they are saving the world, when really Monsanto is just a chemical company (from birth) maximizing profit for shareholders by creating a legal stranglehold on food production. This corporation which is now considered to be a “person” uses GMO’s to make farmers dependent on them to buy their proprietary seed, and then buy their proprietary chemicals, and in addition they sue farmers if they save seed or are inadvertently the victims of wind blown pollen dispersal of GMO’s into other areas on their or neighboring farms.
    If I thought for one minute that GMO’s were actually being utilized to make the world a better place I would seriously look at them as a possible tool, but until they are no longer “owned” by Monsanto and a few other for profit chemical companies I cannot trust the purposes for which they have been designed or utilized.

  4. Too bad this article is complete bullshit. Saying GMOs are completely safe is ridiculous. Who paid for your research Monsanto? Did you get any kickbacks? There is so much evidence saying GMOs are toxic. Look what it is doing to the bee population. Just because someone from Harvard has done a study we should take that as fact?

    1. This article isn’t about one study, it’s about evidence from a bunch of studies (none of which were done at Harvard as far as I can remember). Also, it’s not about environmental effects, to read about the environmental effects you can look here: http://sitn.hms.harvard.edu/signal-to-noise-special-edition-gmos-and-our-food/ . We are a graduate student organization, and we’re not paid by Monsanto, and as far as I know, none of the studies we cited here were either. We are merely interested in providing science articles that are based in primary sources (which is what we are doing here).

      Furthermore, there’s actually little evidence that GM crops have had an effect on bees as far as I can tell, but if you have peer reviewed sources that say otherwise, I’d be really interested in reading them! See here to find studies that show that GM crops have no negative effect on nontarget insects: http://www.ncbi.nlm.nih.gov/pubmed/17556584, http://www.ncbi.nlm.nih.gov/pubmed/15355241, http://www.ncbi.nlm.nih.gov/pubmed/18183296 . The first one actually shows that Bt crop fields have more nontarget insects than nontransgenic fields.

      1. Also, may I ask if you have gathered any information regarding the disadvantages of GM plants? If you could link some non-commercial studies that aren’t older than 5 years that would be a great help to me.

        Thanks

    2. Hey, I wish that were true Randall. I am actually doing an academic research paper on the positives and negatives of GMOs and let me assure you that there is not many studies proving GMOs are toxic, or harmful for that matter. If there were then I wouldn’t have so much trouble trying to find negatives on this topic. Actually I believe that most of the negatives are just fears that people have concerning the potential risks of GMOs, however, those are just potential risks and have not been proved or agreed upon by a scientific body.
      I’m actually going to have a look on some more articles from this page and see if I can find some disadvantages of GMOs.

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