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The (In)Famous Séralini Corn/Roundup® Study with Rats and their Tumors


 This page contains gory pictures of rats with tumors.

Introduction (The Most Disagreeable Introduction I've Ever Made)

One of the most significant elements of the pro-GM and anti-GM debate orbits around certain studies, especially the one we are going to discuss in this page.

If you are acquainted with the "debate", you might have noticed some images that keep coming up, and inevitably raises the emotional level of the heated discussions about the subject of GMOs. Here is the most famous.

Rats of Séralini's Experiment

Source: Séralini et al., 2014, p. 11.

Since then, there is a tendency in most confrontations with anti-GM people. As a philosopher, I call this "Reductio ad Séralini". This is the second favorite strategy by the anti-GM movement right after the "Reductio ad Monsanto". This Reductio ad Monsanto consists in mentioning the name "Monsanto" as a way to win an argument, just like mentioning "Voldemort" in the Harry Potter series. Everyone just assumes that the M-word, it which should not be named, is the equivalent to the Anti-Christ, and all conversation ceases.

But the Reductio ad Séralini is a bit more graphic. It does not involve mentioning Séralini's name, but showing you the picture above, implying that if you ever dare defend Roundup Ready corn and soy or Roundup® itself, then you must be the most despicable human alive.

I understand. After all, the first time I saw these pictures of rats with huge tumors, I was impressed. Who wouldn't? The rat on the left, had GM soy and corn, the one in the middle had only glyphosate (Roundup®) diluted in water, and the third one a combination of both. This picture initially reinforced my conviction that this was evidence that companies like Monsanto were just being irresponsible, especially trying to impose on us its GM, and its glyphosate product.



The "Study" in Question 

The "study" we are discussing was supervised by Gilles-Éric Seralini, a French molecular biologist who carried out an experiment on Sprague-Dawley rats.

There were 200 albino Sprague-Dawley, 100 males and 100 females. Each group was subdivided in groups of 10:

  1. Control group: It was made up of 10 rats (5 males and 5 females), and were given water and non-GM maize.
  2. He gave 60 rats different rates of roundup ready GM maize: 
    1. He gave 20 rats maize with 11% of GM maize: 10 rats would consume it with Roundup and 10 would not.
    2. He gave 20 rats  maize with 22% of GM maize: 10 rats would consume it with Roundup and 10 would not.
    3. He gave the remaining 20 rats maize with 33% of GM maize: 10 rats would consume it with Roundup and 10 would not.
  3. The last three groups of 10 were given non-GM maize, but drank water with Roundup diluted in different rates.
    1. Water with 1.1 x 10-8% of Roundup.
    2. Water with 0.09% of Roundup.
    3. Water with 0.5% of Roundup.

The experiment lasted for two years (Séralini et al., 2012, pp. 4221, 4222-4223).

What were the results?

  1. About 50% of male rats and 70% of female rats died prematurely due to tumors (Séralini et al., 2012, p. 4223).
  2. Only 20% of the male rats and 30% of the female rats in the control group died prematurely due to tumors (Séralini et al., 2012, p. 4223).
  3. Many of the rats ended up having tumors that were 25% of their corporal weight (Séralini et al., 2012, p. 4223).
  4. Other results were presented in a confusing manner, and the majority did not show any correlation at all between the rats' health and the amount of GM soy and maize consumed by them (Séralini et al., 2012, pp. 4223-4228).

The "study" also included a picture similar to the one I have shown above, as well of the tumors, and their cells (Séralini et al., 2012, pp. 4226-4227).

Suspicious Behavior and Fatal Flaws

One of the first indications that there was something fishy about the whole thing was the manner in which this "study" was revealed. If you are a published scientist, you may see that what I am going to say is not exactly the standard procedure for making your work known. And which procedure was it?  A press conference!  How many scientists have called for press conferences when they publish a paper?!  I am not a scientist, but my guess is that these cases must be extremely rare. And not only that, but the press conference by Séralini was not a very usual one. He required the members of the press to sign a confidentiality agreements so that they could access the paper itself before it was published (Arjó et al., 2013, pp. 256, 265, 268; Butler, 2012). Obviously, this was all a show in order to campaign against GMOs in general, after all, Séralini has had a track record of doing that.

The scientific community responded immediately.  Some Antis were baffled by the quick response, yet it shouldn't surprise anyone. If there weren't any press conference and so much propaganda from Séralini's part, most probably there wouldn't have been so much controversy over the "study". Yet, his publicity stunt had the undesired effect of turning everyone's eyes at the article itself.  He wanted attention? He got it!

So, what were the scientists' objections?

The assessments of Member States and EFSA revealed an overall agreement. The study as reported by Séralini et al. was found to be inadequately designed, analysed and reported. The authors of Séralini et al. provided a limited amount of relevant additional information in their answer to critics published in the journal Food and Chemical Toxicology. Taking into consideration Member States’ assessments and the authors’ answer to critics, EFSA reaches similar conclusions as in its first Statement (EFSA 2012). The study as described by Séralini et al. does not allow giving weight to their results and conclusions as published. Conclusions cannot be drawn on the difference in tumour incidence between treatment groups on the basis of the design, the analysis and the results as reported. Taking into consideration Member States’ assessments and the authors’ answer to critics, EFSA finds that the study as reported by Séralini et al. is of insufficient scientific quality for safety assessments. EFSA concludes that the currently available evidence does not impact on the ongoing re-evaluation of glyphosate and does not call for the reopening of the safety evaluations of maize NK603 and its related stacks. EFSA’s evaluation of the Séralini et al. article is in keeping with its role to review relevant scientific literature for risk assessment on an ongoing basis to ensure that the advice it provides is up-to-date.

  • There were also very important breaches of ethics, especially regarding both the design of the experiment in order to force a particular result, and rats' treatment relating to their tumors (see Arjó et al., 2013). In the latter case, I have to point out the degree with which Séralini let the tumors grow to a considerable degree, inflicting unnecessary pain on the rats. Of course, the suspicion is that he let them grow considerably so that they could be photographed with the purpose of impressing the public. This is the reason why Séralini called for a press conference all along.

For these and many other reasons (including errors of lack in clarity, presentation, and others), the paper was retracted from the Food and Chemical Toxicology journal. Séralini threatened to sue, but instead, he essentially republished the study in another journal in 2014, the Environmental Sciences Europe, which is respectable, but has the tendency of publishing some anti-GM articles. That journal also published an article with no data whatsoever that supposedly showed the lack of consensus in the scientific community regarding GM-safety. Here I comment on it. By the way, the journal refused to peer-review this republication, using as an argument that it was not needed, because the paper was peer-reviewed before.


Similar Responsibly Controlled Experiments and Their Results

Some scientists were a bit outraged at the fact that Séralini's experiment was retracted, and asked the Food and Chemical Toxicology journal to carry out an experiment that is funded by non-for profit organizations, and that has an equal share of people from both sides of the debate. Other scientists have pointed out that these experiments have already been carried out. For example, Mark Tester mentioned two relevant experiments about this:

  • Sakamoto  et al., 2008: The experiment consisted in feeding F344 rats Roundup Ready soybean. This experiment was long term, it took about 104 weeks (more than two years). There were not adverse effects on the rats. The experiment was properly controlled: it measured the rats' weight end daily intake. According to the abstract, here is the result: "In pathological observation, there was neither an increase in incidence nor any specific type of nonneoplastic or neoplastic lesions in the GM soybeans group in each sex. These results indicate that long-term intake of GM soybeans at the level of 30% in diet has no apparent adverse effect in rats."

  • Snell et al., 2012: This paper is a meta-analysis on twelve long term studies, and another twelve multi-generational studies on the effects GM maize, potato, soybean, rice, or triticale on animals. None of the 24 studies detected any sign of harm to the animals. The results are described in the abstract as follows: "Results from all the 24 studies do not suggest any health hazards and, in general, there were no statistically significant differences within parameters observed. However, some small differences were observed, though these fell within the normal variation range of the considered parameter and thus had no biological or toxicological significance. If required, a 90-day feeding study performed in rodents, according to the OECD Test Guideline, is generally considered sufficient in order to evaluate the health effects of GM feed. The studies reviewed present evidence to show that GM plants are nutritionally equivalent to their non-GM counterparts and can be safely used in food and feed."



Some have called Séralini's experiment a fraud. Others have stated that there was no intent at deception. Either way, this study has been thoroughly discredited. The main difference between the 2012 version and its republication in 2014 is that the experiment turns out to be inconclusive. In other words, the study itself has not contributed to understand anything regarding the safety or risks of GM maize or glyphosate. This has been a complete waste of time, effort, money, and resources.


Additional Note: A Sad Story

Séralini's effort for using this experiment as an anti-GM propaganda, has had very sad results, especially in two African countries: Uganda and Kenya. In both of these countries, farmers have been facing the problem of bacterial wilt in their banana plantations. African scientists with the help of some private and non-profit organizations are tying to experiment with the possibility of a banana that can resist the bacterial wilt. Yet, because Séralini's publicity stunt reached Africa, Uganda and Kenya made their respective legislation to forbid any sort of research on transgenic or GMO technology. All over radio and TV, there was propaganda linking GM in general with cancer. Even when the organization which carried out this propaganda apologized for the misleading ad, it was too late.  Today, in Kenya, you can be sentenced to prison for 10 years if you are caught working on any GMOs, even if it is good for the public and for farmers.

Given this scenario, Ugandan and Kenyan farmers can't do anything, but sit back and watch their plaintations being ruined. This situation condemns them to starve. In Kenya, there used to be experiments with drought tolerant maize, something that is very needed in Africa. Because of the GM ban, this is practically impossible in Uganda and Kenya. Other farmers in other African countries are taking advantage of this technology, and it has improved their lives.



Academic Review. (2012, Sept. 24). The Academic Review’s editorial standpoint on Seralini’s paper. Retrieved from http://academicsreview.org/2012/09/scientists-smell-a-rat-in-fraudulent-study/.

Arjó, G., Portero, M., Piñol, C., Viñas, J., Matias-Guiu, X., Capell, T., Bartholomaeus, A., Parrott, W. & Christou, P. (2013, Feb. 22). Plurality of opinion, scientific discourse and pseudoscience: an in depth analysis of the Séralini et al. study claiming that Roundup™ Ready corn or the herbicide Roundup™ cause cancer in rats. Transgenic Research, 22, 255-267. doi.10.1007/s11248-013-9692-9. Retrieved from http://link.springer.com/article/10.1007%2Fs11248-013-9692-9.

Berry, C. (2013, March). Letter to the editor. Food and Chemical Toxicology, 53, 445-446. doi:10.1016/j.fct.2012.10.053. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512007983

Butler, D. (2012, October 10). Hyped GM maize study faces growing scrutiny. Nature, 490 (158). doi:10.1038/490158a. Retrieved from http://www.nature.com/news/hyped-gm-maize-study-faces-growing-scrutiny-1.11566.

Casassus, B. Study linking GM maize to rat tumours is retracted. Nature. doi:10.1038/nature.2013.14268. Retrieved from http://www.nature.com/news/study-linking-gm-maize-to-rat-tumours-is-retracted-1.14268.

CNRS. (2012, Sept. 27). Pour un débat raisonné sur les OGM. Retrieved from http://www.cnrs.fr/fr/une/actus/2012/20120927-debat-ogm.html.

Dunklee, D. D. (2014, March). Letter to the editor. Food and Chemical Toxicology, 65, 393. doi:10.1016/j.fct.2014.01.005. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691514000064.

Durbin, P. W., Williams, M. H., Jeung, N. & Arnold, J. S., Parrott, M. W. & Davis, T. (1966, March). Development of spontaneous mammary tumors over the life-span of the female Charles River (Sprague-Dawley) rat: the influence of ovariectomy, thyroidectomy, and adrenalectomy-ovariectomy. Cancer Research, 26 (1), 400-411. Retrieved from http://cancerres.aacrjournals.org/content/26/3_Part_1/400.full.pdf.

EFSA. (2012). Final review of the Séralini et al. (2012a) publication on a 2-year rodent feeding study with glyphosate formulations and GM maize NK603 as published online on 19 September 2012 in Food and Chemical Toxicology. EFSA Journal, 10 (11), 2986. doi:10.2903/j.efsa.2012.2986. Retrieved from http://www.efsa.europa.eu/en/efsajournal/pub/2986.htm.

Folta, K. (2014, Jan. 3). Letter to the editor. Foood and Chemical Toxicology, 65, 392. doi:10.1016/j.fct.2014.01.004. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691514000052.

Landgridge, P. (2013, March). Letter to the editor. Food and Chemical Toxicology, 53, 441. doi:10.1016/j.fct.2012.10.056. Retrieve from http://www.sciencedirect.com/science/article/pii/S0278691512008010

Le Tien, D. & Le Huy, H. (2013, March). Comments on “Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize”. Food and Chemical Toxicology, 53, 443-444. doi:10.1016/j.fct.2012.10.054. Retrieve from http://www.sciencedirect.com/science/article/pii/S0278691512007995.

Nakazawa, M., Tawaratani, T., Uchimoto, H., Kawaminami, A., Ueda, M., Ueda, A., Shinoda, Y., Iwakura, K., Kura, K. & Sumi, N. (2001). Spontaneous neoplastic lesions in aged Sprague-Dawley rats. Experimental Animals, 50 (2), 99-103. doi:10.1538/expanim.50.99. Retrieved from https://www.jstage.jst.go.jp/article/expanim/50/2/50_2_99/_article.

Narbonne, J. F. (2012, Sept. 21). Lacunes, résultats inexplicables: l'étude anti-OGM sur la sellette. The Huffington Post. Retrieved from http://www.huffingtonpost.fr/jeanfrancois-narbonne/lacunes-resultats-suprenants-et-inexplicables-letude-anti-ogm-sur-la-sellette_b_1902634.html.

Ng. A. (2012, Sept. 24). Genetically modified corn and cancer – what does the evidence really say? The Conversation. Retrieved from http://theconversation.com/genetically-modified-corn-and-cancer-what-does-the-evidence-really-say-9746.

Ollivier, L. (2013, March.). A Comment on “Séralini, G.-E., et al., Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize. Food Chem. Toxicol. (2012),” http://dx.doi.org/10.1016/j.fct.2012.08.005. Food and Chemical Toxicology, 53, 458. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512007909.

Oransky, I. (2014, Jan. 16). Journal editor defends retraction of GMO-rats study while authors reveal some of paper's history. Retraction Watch. Retrieved from http://retractionwatch.com/2014/01/16/journal-editor-defends-retraction-of-gmo-rats-study-while-authors-reveal-some-of-papers-history/.

Prejean, J. D., Peckham, J. C., Casey, A. E., Griswold, D. P., Weisburger, E. K. & Weisburger, J. H. (1973, Nov.). Spontaneous tumors in Sprague-Dawley rats and Swiss mice. Cancer Research, 33, 2768-2773. Retrieved from http://cancerres.aacrjournals.org/content/33/11/2768.

Power, M. (2013, June 29). Drinking Roundup herbicide makes men live longer. Myles Power [Blog]. Retrieved from http://mylespower.co.uk/2013/06/29/drinking-roundup-herbicide-makes-men-live-longer/.

Sakamoto, Y., Tada, Y., Fukumori, N., Tayama, K., Ando, H., Takahashi, H., Kubo, Y., Nagasawa, A., Yano, N., Yuzawa, K. & Ogata, A. [A 104-week feeding study of genetically modified soybeans in F344 rats]. Shokuhin Eiseigaku Zasshi, 49 (4), 272-82. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/18787312.

Schorsch, F. (2013, March). Letter to the editor:  Serious inadequacies regarding the pathology data presented in the paper by Séralini et al. (2012). Food and Chemical Toxicology, 53, 465-466. doi:10.1016/j.fct.2012.10.043. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512007880.

Science Media Centre. (2012, Sep. 19). Expert reaction to GM maize and tumours in rats. Retrieved from http://www.sciencemediacentre.org/expert-reaction-to-gm-maize-causing-tumours-in-rats/.

Science Media Centre. (2014, Jan. 25). Controversial GM study republished – experts respond. Retrieved from http://www.sciencemediacentre.co.nz/2014/06/25/controversial-gm-study-republished-experts-respond/.

Séralini, G.-E., Clair, E., Mesnage, R., Gress, S., Defarge, N., Malatesta, M., Hannequin, D. & Spiroux de Vendômois, J. (2012, Nov.). Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize (Retracted). Food and Chemical Toxicology, 50 (11), 4221-4231. doi:10.1016/j.fct.2012.08.005. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512005637.

Séralini, G.-E., Clair, E., Mesnage, R., Gress, S., Defarge, N., Malatesta, M., Hannequin, D. & Spiroux de Vendômois, J. (2013, Jan.). Retraction notice to “Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize” [Food Chem. Toxicol. 50 (2012) 4221–4231]. Food and Chemical Toxicology, 63, 244. doi:10.1016/j.fct.2013.11.047. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691513008090.

Séralini, G.-E., Clair, E., Mesnage, R., Gress, S., Defarge, N., Malatesta, M., Hannequin, D. & Spiroux de Vendômois, J. (2014, June 14). Republished study: long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize. Environmental Sciences Europe, 26 (14). Retrieved from http://www.enveurope.com/content/26/1/14.

Snell, C., Bernheim, A., Bergé, J.-B., Kuntz, M., Pascal, G., Paris, A. & Ricroch, A. E. (2012, March-April). Assessment of the health impact of GM plant diets in long-term and multigenerational animal feeding trials: a literature review. Food and Chemical Toxicology, 50 (3-4), 1134-1148. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691511006399.

de Souza, L. & Oda, L. M. (2013, March). Letter to the editor. Food and Chemical Toxicology, 53, 440. doi:10.1016/j.fct.2012.10.057. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512008022.

Suzuki, H., Mohr, U. & Kimmerle, G. (1979, Oct.). Spontaneous endocrine tumors in Sprague-Dawley rats. Journal of Cancer Research and Clinical Oncology, 95 (2), 187-196. Retrieved from http://link.springer.com/article/10.1007%2FBF00401012

Tester, M. (2013, March). Letter to the editor. Food and Chemical Toxicology, 53, 457. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512007910.

Trewavas, A. (2013, March). Letter to the editor. Food and Chemical Toxicology, 53, 449. doi:10.1016/j.fct.2012.10.050. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512007958.

Tribe, D. (2013, March). Letter to the editor. Food and Chemical Toxicology, 53, 467-472. Retrieved from http://www.sciencedirect.com/science/article/pii/S0278691512007879.


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