Science in Society Archive

GM Cancer Warning Can No Longer Be Ignored

The latest findings of cancers and deaths from GM maize and Roundup herbicide are the result of the most in-depth long-term toxicology study ever done on GM food; we ignore them at our peril Prof Peter Saunders and Dr. Mae-Wan Ho

In the Vatican Museums in Rome stands a statue of La0coön and his sons. Legend has it that Laocoön tried to warn his fellow citizens against taking in the wooden horse that the Greeks had left outside their gates. It was not a gift, but a ruse designed to allow Greek soldiers to enter the city. The Greek gods, who wanted to see Troy destroyed, sent sea serpents to kill Laocoön. This convinced the Trojans that the horse was indeed sacred; so they opened the gates and dragged it into the city. The result was the total destruction of Troy and its empire.

The biotech industry is doing its best to convince us that GMOs are the key to feeding a hungry world, when all the evidence is that they profit only the companies. Whenever anyone tries to warn of the dangers of GMOs, the industry responds by doing its utmost to discredit the whistle blower and prevent the warning from being heard. We have already witnessed what happened to Arpad Pusztai ([1] Pusztai Publishes Amidst Fresh Storm of Attack , I-SIS News 3), David Quist and Ignacio Chapela ([2] Who's Afraid of Horizontal Gene Transfer?, SiS 15) and Irina Ermakova ([3] Science and Scientist Abused, SiS 36) to name but a few; also Nancy Oliviera ([4] Big Business = Bad Science? ISIS News 9/10) and David Healy ([5] The Depressing Side of Medical Science, SiS 39) with the pharmaceutical industry no less corrupt than biotechnology.

GM maize and herbicide link to cancer “a bomb”

The latest warning - perhaps the most dramatic to-date – comes in a paper published online 19 September 2012 in the journal Food and Chemical Toxicology reporting high rates of death and cancers in rats fed Monsanto’s GM maize NK603 and/or Roundup herbicide compared with controls [6]. The study carried out by Gilles-Eric Séralini and his group at the University of Caen involved the largest number of rats followed for their entire lifespan of two years. By all accounts, it was the most in-depth long-term toxicology study ever done on GM food [7]. Séralini reported the results in the European Parliament.

France’s former Environment minister Corinne Lepage MEP said the study was “a bomb” calling into question all existing regulatory authorizations of GMOs. GMOs are approved in the European Union and elsewhere on the basis of a 90-day toxicology study at best, carried out by the biotech companies. The key finding of the new study is that tumours and other serious health impacts appeared at 4-7 months, which would have been missed in all previous tests.

On the same day the study was published, the French government asked a health watchdog, The National Agency for Health Safety to investigate the new findings [8]. The next day, Austria called for EU to review its approval process for GM food [9]. Within a week, Russia suspended import and use of GM corn from the USA [10]. On 10 October, the company Vilmorin, the world’s fourth largest seed group and a holding of Limagrain dropped its planned GM field trials in France [11].

The response from the pro-GM lobby was equally dramatic and immediate. The UK industry-funded Science Media Centre (SMC) issued quotes from “experts” (with undisclosed conflict of interest) in an attempt to discredit the study. This was followed by a deluge of attacks and off the cuff and largely irrelevant criticisms from the scientific establishment and official regulatory bodies around the world (see later).

The notorious European Food Safety Authority (EFSA), which authorized the GM maize, issued its initial review of the study – pending a detailed review - claiming, unsurprisingly, that there is no need to re-evaluate the safety because the study is of “insufficient scientific quality”.  Lepage expressed serious concerns about EFSA’s initial review, which did not read like carefully considered opinions but hastily put-together points circulated by the pro-GM lobby. She highlighted the conflict of interest in Andrew Chesson, one of the only two people appointed by EFSA to review the study, who was on the panel that originally approved the GM maize NK603 and actually helped prepare the draft document recommending its approval. Thus, Chesson is acting as “both judge and jury” [7]. Chesson, it turns out, was also involved in discrediting his former colleague Arpad Pusztai; he chaired the audit committee that found fault with Pusztai’s research.

EFSA has since been criticized by the European Court of Auditors for inadequate management of conflicts of interest [12]. This came as no surprise as conflicts of interests are rife within EFSA. Earlier in May 2012, the Chair of EFSA’s Management Board was forced to quit because of her industry links. Just a month earlier, EFSA admitted to the European ombudsman that it had not properly responded to the case of Suzy Renckens, the former head of EFSA’s GM unit, who left EFSA and moved to a lobbying job with the biotech giant Syngenta. And GMO panel chair Harry Kuiper clearly used his position to influence the work of the panel in a pro-industry direction.

Friends of the Earth condemned EFSA for having consistently sided with the biotech industry and disregarded health or environmental concerns about GM crops. It called on national governments and EU safety authorities to immediately suspend all Roundup-t0lerant GM crops from market, the European Commission to suspend all new GMO approvals and to start and root-and-branch reform of how the risks of GM foods are to be assessed, and for the EU to review the safety of the herbicide Roundup (glyphosate), including the link between GM crops and the use of the herbicide. Greenpeace too, called for immediate freeze on approvals of new GM crops and a redesign of safety testing over the long term. They should both call for banning glyphosate as the damning evidence on glyphosate is even stronger than for GMOs, and the maximum permitted levels of glyphosate are set to rise by 100-150 times in the European Union if Monsanto has its way (see [13] Why Glyphosate Should Be Banned, I-SIS Report).

The most thorough and long-term toxicology test to-date

The findings reported by Séralini’s group are not those of an isolated study suddenly to reveal that GM feed and the most widely used herbicide in the world may be toxic or carcinogenic. They are the latest of similar findings from laboratory experiments backed up by the experience of farmers and farm workers around the world [13].

In 2007, EFSA gave approval for Monsanto’s MON 863, MON 810 and NK603 maize, all genetically engineered to be tolerant to Monsanto’s Roundup herbicide, on the basis of evidence from the company’s feeding trials on rats. Differences showed up between rats fed GM maize and the controls, but were dismissed as “not biologically significant” [6].

Séralini and his group at Caen brought a Freedom of Information suit in the European Court to obtain the raw data from Monsanto. On re-analyzing the data, they found that contrary to what the company had claimed and the regulator had accepted, there were indeed statistically and biologically significant differences.

But EFSA analysed the data again, and reported that they were still satisfied that none of the differences was biologically significant. Séralini and his group decided that the best way to settle the issue would be to conduct their own experiment.

It turned out to be difficult to arrange the trials because the stewardship agreements farmers have to sign forbid not only saving seeds but also their use for research without specific permission [14]. This effectively prevents anyone else to learn anything about GM crops beyond what the company wants them to hear.

After some effort, the group in Caen were able to get hold of suitably grown GM maize, NK 603, and a near equivalent non-GM variety [6]. They used 200 animals (100 males and 100 females) in their experiment, which lasted for two years; in contrast, regulatory tests usually last only up to three months and may involve as few as 10 animals. They ran the experiment following Good Laboratory Practice (GLP) and the OECD protocol for toxicity trials, and measured more parameters and more frequently than the OECD protocol requires.

In order to distinguish effects caused by the GM maize, or the herbicide, or both, Séralini and his colleagues divided the male and female rats separately into nine treatment groups,each with ten rats. Three were given in their feed different proportions of GM maize that had been sprayed with Roundup herbicide, three were given the same proportions of GM feed that had not been sprayed, and three were given the closest isogenic (i.e. non-GM) maize but had different amounts of Roundup added to their water. The tenth group was given only non-GM maize with standard feed and plain water.

The amounts of Roundup that were added were (a) the amount often found in tap water,  50ng/L glyphosate, (b) the US maximum residue limit (MRL) for glyphosate in some feeds, 400 mg/kg, and 2.25 g/L, half the minimal agricultural working dilution. They used Roundup in the experiments, whereas most trials have been conducted using only glyphosate. The difference is that like most proprietary formulations, Roundup contains adjuvants, substances added to enable the active principle (i.e. glyphosate) to penetrate the target plant organism efficiently, and it seems reasonable to suppose that these might alter its effect on non-target organisms as well.

As they expected from their analysis of Monsanto’s results, Séralini and his team found signs of toxicity in the livers and kidneys of the treated rats. The most worrying effect, however, and one that had not been anticipated when the experiment was designed, was the increase in the number of early deaths and of tumours.  Among females, there were 2-3 times as many deaths in all treated groups compared to controls by the end of the experiment. By the beginning of the 24th month, 50-80 percent of female animals had developed tumours in all treated groups, whereas only 30 per cent of controls were affected.

In treated males, liver congestions and necrosis were 2.5-5.5 times controls, with marked and severe kidney disease 1.3-2.3 times controls. Males also presented 4 times as many large tumours than controls and up to 600 days earlier.

Biochemical data confirmed “very significant” kidney chronic deficiencies for all treatments and in both sexes; as 76 % of the altered parameters were related to the kidney.

A summary of the most striking observations are given in Table 2.  For the six most frequently observed anatomical pathologies, in all but 3 of the 54 cases (i.e., 9 differently treated groups for each of the 6 pathologies) the number of rats affected was greater than in the corresponding control. The results were backed up with photographs of the afflicted rats and histological changes in the tissues, as well as biochemical analyses, which gave strong indications of kidney deficiency in both sexes. The results clearly cannot be dismissed as being due to chance.

The anatomical pathologies  are so striking that the team did not bother to carry out any of the standard tests that could have been used, as pointed out by a former research analyst with a major government agency, who defended the study against critics but wishes to remain anonymous [15, 16]. He commented [15]: “Table 2 stood out, with the doubling and tripling of pathologies in treatment groups compared with controls, with as many as 8, 9, or even all 10 treatment rats in a group affected. This made me question how a study in which such high numbers of rats were affected, could be dismissed.”

The criticisms do not stand up

As collated and reviewed by UK group GMWatch [7], most if not all the criticisms are irrelevant or ill-considered, being hastily put together to confuse the public, and have been answered in full, by Seralini’s group and a host of other scientists. For example, they complained that the Sprague-Dawley rats were the wrong animals to use; that strain happens to be the standard for routine toxicology tests. Monsanto dismissed the findings, in that they “fall within historical norms for this strain of laboratory rats, which is known for a high incidence of tumours”. Monsanto meant by ‘historical norm’ control data cobbled from various other studies in the scientific literature or elsewhere, a thoroughly unscientific and non-standard practice designed to explain away undesirable results. Controls are specific to experiments and precise conditions of rearing, and it is totally unacceptable to lump data from different controls together to compare them with any one specific experiment.

Another complaint was that Séralini and his team did not follow the OECD protocol for tests for carcinogenesis, which would have required groups of 50 animals instead of 10. In fact, they used the toxicity protocol because that was what the experiment had been designed to do, and which actually made it less likely to detect carcinogenesis. The fact that high rates of cancer were detected with far fewer animals makes the findings all the more serious (see [17, 18] Excess Cancers and Deaths with GM Feed: the Stats Stand Up, SiS 56).

The dust had hardly settled when another attack was launched; one purporting to be from the six French Academies (science, technologies, medicine, veterinary science, agricultural sciences, pharmacy) [19]. In fact, it was put together in great haste by a group of two representatives from each of the Academies. It is not known who the members are or who appointed them or by what process. The group specifically did not include or consult Paul Deheuvel, the only member of the Academy of Sciences who represents statistics.  Deheuvel has since issued his own favourable comments on Séralini’s work, which he judges to be of high quality and to have used statistics appropriately [20]. He points out in particular that the critics have concentrated on the carcinogenesis part of the results, which are the most dramatic but which the experiments had not been designed for, and largely ignored the toxicology, which is still very important.

The citizens of Troy came to bitterly regret their decision to ignore Laocoön’s warnings and allow the Trojan horse to enter their city. The citizens of the world can no longer afford to ignore Seralini’s warnings and allow GMOs and Roundup herbicide to continue devastating people and planet.

Article first published 24/10/12


  1. Puztai publishes amidst fresh storm of attack. ISIS News 3, December 1999.
  2. Ho MW and Cummins J. Who’s afraid of horizontal gene transfer? Science in Society 15, 12, 2002.
  3. ISIS. Science and scientist abused. Letter to Nature Biotechnology. Science in Society 36, 8, 2007.
  4. Saunders PT and Ho MW. Big Business=Bad Science? i-sis news 9/10  11-12, 2001.
  5. Healy D. Let Them Eat Prozac. New York University Press, New York and London, 2004.  See also the review by PT Saunders: The depressing side of medical science. Science in Society 39 50-51, 2008.
  6. Séralini G-E, Clair E, Mesnage R, Gress S, Defarge N, Malatesta M, Hennequin D, de Vendômois J-S. Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize. Food and Chemical Toxicology published online September 2012.
  7. GM Watch Monthly Review 109 Part 1: Seralini, 15 October 2012,
  8.  “France orders probe after rat study links GM to cancer”, Agence France-Presse, 19 September 2012,
  9. “Austria wants EU review of GM corn policy”, Reuters, 20 September 2012,
  10. “Russia suspends import and use of American GM corn after study revealed cancer risk”, Sean Poulter, Daily Mail 25 September 2012,
  11. “Vilmorin drops GM field tests as debate rages in France”, Gus Trompiz, Reuters, 10 October 2012,
  12. “EFSA criticised by auditors over conflicts of interest”, Corporate Europe Observatory, 11 October 2012,
  13. Sirinathsinghji E and Ho MW. Why glyphosate should be banned. I-SIS special Report, and Science in Society 56 2012.
  14. “Wanted: scientific integrity on GMOs”, Marcia Ishii-Eliteman, Ground Truth 23 February 2012,
  15. Comment on Seralini findings and stats by former government analyst. GMWatch 1 October 2012,
  16. Comment on attacks on Seralini by former government analyst. GMWatch 4 October 2012,
  17. De Heuvels P. Étude de Séralini sur les OGM : pourquoi sa méthodologie est statistiquement bonne. Le nouvel observateur Le Plus, 2012, accessed 12 October 2012,
  18. Saunders PT. Excess cancers and deaths with GM feed: the stats stand up. Science in Society 56 2012.
  19. Avis des Académies nationales d’Agriculture, de Médicine, de Pharmacie des Sciences, des Technologies et Vétérinaire sur la publication récente de G. E. Séralini et al. sur la toxicité d’un OGM.
  20. “L’etude de Séralini sur les OGM, pomme de discorde a l’Academie des Xciences”, Paul Dehaeuvels, Membre de l’Academie des Sciences, Le Plus, 19 October 2012,

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John Fryer Comment left 25th October 2012 02:02:40
Black Monday 2012 October 22 The day that Monsanto and ANSES the French regulators collaborated to deny science its voice. It would cost billions to undo the harm from NK603 maize and human illness and death so better to tough it out and pretend this research was at the same quality as Monsanto research into safety. I found it difficult to understand why the regulators talk of multitudes of experiments on GMO soya. Do they know that Seralini did his research on GMO maize? Yes, they did but they could not understand what it was telling the world. A summary is: Take NK603 Monsanto maize off the market as it causes illness, cancers and deaths. The police might be better arbitrators on this than governments and regulators with too much money invested and provided by Monsanto. This is not just about plain danger but fraud, criminality and possible genocide schemes. The flaw in this scheme is that no one but no one is immune from the biological FALLOUT both today or in the future generations.

Desiree L. Rover Comment left 25th October 2012 02:02:15
This study makes it very clear to me as a medical research journalist that the multinational corporations and the governmental institutes know exactly what they are doing: culling us 'useless eaters' in every way possible, to reach their Agenda 21 and chiseled Guidestones dreams of "Maintain humanity under a permanent 500,000,000 in perpetual balance with nature". Genetic manipulation of the food supply merely is one of the many 'tools' I see being used by the-powers-that-so-bloody-wannabee. Vaccines, chemtrails, the ongoing Corexit spraying in the Gulf, Fukushima, weather manipulation, abusing electromagnetic frequencies, power grids are some more examples. Whatever ‘the elite’ are doing, it is aimed at making us stupid, sick, sterile, and a stiff...

Jose Bulatao, Jr. Comment left 25th October 2012 04:04:39
Who will speak for the common man, woman, and child living in the various communities on the island of Kauai surrounded by the conglomerate GMO companies utilizing thousands of acres to grow their GMO crops? Our lives and our environment are being affected by the presence and activity of GMO conglomerates in our midst. Who has the responsibility to monitor the daily use of herbicides and pesticides upon the land, the water resources, and the air we breathe, as well as the accumulative effect and impact on the environment and upon the lives of the people on the island?

Eefje Willemze-Kool Comment left 25th October 2012 18:06:46
I am appalled @ what is going on, and is allowed to go on.It certainly seems criminal to me. I agree with JohnFryer (above). take it off the market; let the police arbitrate re the criminality of Monsanto's actions.

Todd Millions Comment left 25th October 2012 18:06:42
Given the high price I paid(and pay),with starlink bt corn contamination-I should be very interested to learn of any studies on the rats joints and organs for inflamation.Given the documented pollen spread of up to 1500 Km-its of course too late to do anything(2% of hybrid pollen is viad),except too start claims of damages-Nafta(chapter 11)style,exemptions from liability,WITH patent protection notwithstanding.Posting open ended bonds of all assets and incomes,banked where ever for damages seems only fair too more than me.

Rory Short Comment left 26th October 2012 02:02:01
The callous pursuit of money at any cost to the environment and people, that is the nature of Monsanto and of other GMO seed companies. It is the same as the attitude of tobacco companies to the research findings on the damaging consequences of smoking. They should all appear before the world court accused of genocide.

Susan Rigali Comment left 27th October 2012 19:07:59
This Wednesday 24 recognized as world food day, I went to work very early in order to find time to be in Los Angeles County Court by 9 am. I have worked many years in my "democratic" country and have been somewhat of a nuisance in my representatives offices for many years. When I arrived at court many protestors were present for a hearing deciding city council support for labeling GMO's. The police guided all demonstrators to an outside terrace where a small speaker was barely audible. We were told we would only be allowed entrance to the courtroom if our names were called. This was discouraging as last months meeting was cancelled to the public. After several hours, myself and others moved demonstrators inside by saying they needed to use the facilities. The crowd again became a presence and several of us got in by saying our names were called. Court dismissed seiu labor union and then allowed Prop 37 supporters for labeling into the courtroom. Although many signed up for comment around ten supporters were given a minute each to speak. Many speakers had health issues and others questioned the legality or democratic principle of primarily Monsanto practices. I was not given an opportunity to speak but when a council member said the science was still out on gmo's, I could not sit silent. My reply was "NO it isn't. What about independent science." I was told to refrain at which point I said "What about the rest of the world" I walked out in disgust as my representative admonished me for interrupting an elected official. Even though the vote would be unanimous in support for labeling and I am grateful to every person who voted for this change I still felt some remorse for all the contamination that has occurred, for the years spent trying to make a change, but mainly for many people who are experiencing hardships with health and environmental concerns.

Sir Julian Rose Comment left 29th October 2012 01:01:16
Last month the International Coalition to Protect the Polish Countryside hosted Sophia Gatika in Krakow. Sophia Gatika had already spoken in the European and German Parliaments. Her shocking story of sickness and death in her community in Argentina as a result of mass glyphosate spraying of GM soya exposed just how extreme is the situation on the ground where such activities take place. Here is the list of sicknesses attributed to the spraying in the community, as analysed by the University of Buenos Airies: leukemia cancer lupus tumours anemia hepatitis infant death The fact that both Sophia Gatika's painful facts (she lost her own daughter due to the spraying) about the human carnage due to Glyphosate poisoning and prof.Seralinis expose of GM maize and glyphosate in relation to feeding experiments on ropdents - can surely leave no one in doubt that an outright ban of GMO must be set in motion without further delay.

Luis Arturo Echevarría Comment left 31st July 2013 01:01:29
Santuario Transgénico. Desde San Luis, ARGENTINA hago llegar a Uds. información sobre la instalación de MONSANTO. Ver enlace. Y por las implicancias socio ambientales que ha generado deseo compartir una entrevista con una visión distinta a los lineamientos transgénicos de Monsanto. Un cordial saludo. Ing. Luis Arturo Echevarría

Eva Sirinathsinghji Comment left 31st July 2013 22:10:46
I have translated the original comments made by Mr Luis Echevarria in Spanish into English English Translation: Transgenic Sanctuary in San Luis, Argentina. I submit information to you about Monsanto's planned installation of a factory for transgenic seeds. See link And due to the social environmental consequences I would like to share an interview with a different point of view to the line given by Monsanto. Kind Regards. Ing. Luis Arthur Echevarria This comment links to articles in Spanish. The first, published on the website of the Red Universitaria de Ambiente i Salud, Argentina describes the new installation of a GM seed production factory in Argentina as well as the consequences this will have on the region. The various GM seeds of both Bt and glyphosate-tolerant varieties have had adverse health and environmental consequences on the region already, which will only worsen with the further cultivation of seeds in the new factory in San Luis. There are concerns for the potential pollution of large lucrative ground water supplies in the area, as well as the exploitation of workers, as has been reported with Monsanto and other seed corporation employees in other parts of Argentina. The article finishes with the rebuttal of the biotech claims that GM crops feed a world that would otherwise go hungry, when UN statistics prove there is sufficient food to feed the global population, instead highlighting the role of multinationals such as Monsanto who cause “inequity of the system; increasing grain production and consequent destruction of nature (water, soil, biodiversity), land grabbing, evictions of peasants, extermination of native peoples, concentration of wealth, etc.. one is grounded in seeking to maximize the profits of the groups that dominate the food market, local partners and government partners. That is, excess food is distributed badly, because the food market does not look to make sure everyone can eat, their sole purpose is to make money” (translated from the original in Spanish). The University does not want this region, rich in culture and beautiful nature, to be at the mercy of these poisonous, monopolising agritech corporations. The second article is an interview with Luis Arthur Echevarria himself, who further clarifies the harmful effects GM chemical agriculture has had on Argentina. He highlights that GM seeds are a clear breach of nature and furthermore, have led to huge rises in pesticide use that has had alarming effects on the health of the people and the land, a problem that desperately requires tighter regulation. Echevarria, an agricultural engineer, holds the Argentinean government responsible for letting in dangerous multinationals without conducting the necessary safety tests to ensure there would be no risks to the Argentinean population.