The GM maize rats

Findings of the Seralini lab on effect of Monsanto’s GM maize on rats set off a global furore

By Latha Jishnu
Last Updated: Sunday 07 June 2015

The GM maize rats

Three weeks ago, a university institute in Normandy, France, sparked fury, outrage and an astonishingly vicious battle between scientists across the world by publishing results of a two-year animal feeding study. The study involved one of the best known varieties of genetically modified (GM) maize and the most widely used glyphosate-based herbicide. The study was published by a team of scientists led by the highly regarded Gilles-Eric Seralini who heads the Institute of Biology at the University of Caen in France.

GILLES-ERIC SERALINI We are surprised by the violent and rapid reactions by scientists within 24 hours. Was it because of their financial interests?

Seralini and his team of seven conducted a lifetime feeding trial of the herbicide-tolerant maize known as NK603, a product of agribiotech giant Monsanto of the US, and of its extensively used herbicide Roundup, on 200 rats for two years. Roundup kills weeds without harming the crops. It was the first time that the health impact of a GM crop and a widely used pesticide was studied for this length of time and in a more comprehensive manner than studies done by regulatory agencies, industries or by research institutes. The two-year study was designed to correspond with the expected lifetime of a normal rat whereas the industry practice is 90-day study.

The team used 100 female and 100 male rats. In both sets, some rats were fed NK603, some the GM maize sprayed with Roundup, and the third group was given drinking water with the lowest permissible limit of Roundup. A fourth, control group was fed a standard diet of the closest variety of non-GM maize.

The results were alarming, according to the peer-reviewed paper published in Food and Chemical Toxicology, a journal from the reputed Elsevier stable. Rats that fed on NK603 or given water containing Roundup died much earlier than the rats in the control group and developed hormonal and sex-related effects. Females developed significant mammary tumours, pituitary and kidney problems, while males died mostly from severe kidney failure. Up to 50 per cent of the male rats and 70 per cent of females died prematurely, compared with only 30 per cent and 20 per cent in the control group.

In female rats, the largest tumours were five times more frequent than in males, with 93 per cent being mammary tumours. These were deleterious to health due to their large size and caused impediments to breathing or nutrition and digestion

The implications are extremely serious, says a press note issued by CRIIGEN, an independent organisation of scientific experts that studies genetically modified organisms (GMO), pesticides and impacts of pollutants on health and environment, on the research results. “They demonstrate the toxicity, both of a GMO with the most widely spread transgenic character and of the most widely used herbicide, even when ingested at extremely low levels (corresponding to those found in surface or tap water).” The scientists point out that these results call into question the adequacy of the current regulatory process which is used the world over in assessing the health risks associated with such products. They, therefore, demand that the market approval for these products should be immediately reviewed and urged the extension of the usual 90-day test to two years for agricultural GMOs.

“It was surprising. We didn’t expect the kind of tumours that we saw appearing in the rats in the fourth month (industry trials end at three months) of our experiment,” says Robin Mesnage, member of the Seralini research team who was in India to attend the conference of parties to the Convention on Biodiversity in Hyderabad. “And these tumours in rats eating the Roundup-tolerant GM maize began to appear so much earlier than in the control group.”

Major health implications for humans
Michael Antoniou, head of the Nuclear Biology Group in the UK, has been studying the health effects of genetically modified (GM) crops since 1995.
Explaining the genesis of the experiment, Mesnage said that the €3.2-million-study was conceived in 2008 when the first of the Seralini team’s researches into the effects of GM maize varieties on mammalian health was nearing completion. Those results which analysed Monsanto’s own 13-week “safety assurance study” by Bruce Hammond et al—the results were published in the very same Food and Chemical Toxicology in 2004—had highlighted concerns over new side effects that were sex-related and dose-dependent. “Effects were mostly associated with the kidney and liver,” notes the paper by Seralini and others.

To see if the signs of liver and kidney toxicity escalated into something serious, Seralini’s team chose a chronic toxicity protocol as per OECD (Organisation for Economic Cooperation and Development) guidelines, which is the general rule. And as the current paper, “Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize”, shows this, indeed, is the case.

But the biotech industry and its cheerleaders have reacted with fury and criticisms that have as quickly been rebutted by independent scientists. Rejecting the findings, Monsanto says, “The study does not meet minimum acceptable standards for this type of scientific research, the findings are not supported by the data presented, and the conclusions are not relevant for the purpose of safety assessment.” (See ‘The company’s rebuttal’). It also makes the standard claim that “plant biotechnology has been in use for over 15 years without documented evidence of adverse effects on human or animal health or the environment.”

Seralini’s professional standing—he has written over 100 scientific articles and has been a member of two French government commissions that oversee risk assessment of GMOs and monitor commercialised GMOs—has not stopped detractors from mounting personal attacks. But support has come from ENSSER (European Network of Scientists for Social and Environmental Responsibility) which says, “The vitriolic attacks evoked by the study reveal the lack of appropriate methodologies for long-term studies to assess the effects of life-time consumption of GM foods.”

Company’s rebuttal
Monsanto, developer of GM NK603 maize and Roundup herbicide, says:


  • Research protocol does not meet OECD standards
  • Source and quality of maize used is unclear
  • Absence of critical details on diet preparation, dietary intake
  • Lack of data on changes in liver or kidney tissues
  • Mortality rates, tumour incidence fall within historical norms
  • Data presented highly selective
  • Lack of statistical analysis for morta lity/tumour incidence endpoints

The quickest rejection of the study came from Maurice Moloney, institute director and chief executive of Rothamsted Research, who said: “Although this paper has been published in a peer–reviewed journal, there are anomalies throughout the paper that normally should have been corrected or resolved through the peer-review process. For a paper with such potentially important findings, it would have been more satisfying to have seen something with a more conventional statistical analysis.” Moloney, who is said to hold more than 300 patents, was earlier with Calgene where he developed the world’s first transgenic oilseeds, which led to the development of RoundUp Ready Canola and other such crops. Calgene was acquired by Monsanto in 1997.

In response to the criticism, Seralini told Down To Earth that: “We are surprised by the violent and rapid reactions by scientists within 24 hours. Was it because of their financial interests? Or, were they involved in the insufficient assessment of agricultural GMOs on health?” But not surprisingly, he adds, “The first reactions have come essentially from people who have not published any peer-reviewed scientific papers on mammalian or human physiological and toxicological studies. This is the case with Maurice Moloney who works on GMO development and patents, not on food safety.”

Moloney was the spearhead for a torrent of criticism from the industry and this has caused unease among independent scientists. Says Jack Heinemann, professor of molecular biology and genetics, University of Canterbury, New Zealand: “The reactions appeared shockingly quick and this is a cause for concern because I find it takes time to thoroughly read a scientific paper of this complexity.”

JACK HEINEMANN The reaction appears shockingly quick. It takes time to thoroughly read a scientific paper of this complexity

While most of the criticism was of a general nature, others were specific, referring to the type of rat used, the kind of statistical analysis, and the interpretation of the response to increasing concentrations of the agrichemicals, Roundup, or GM plant ingredient. But here, too, a review of the seven studies of this kind since 2004 shows that all of these used approximately the same number of rats and all were conducted on the same kind of rat (Sprague Dawley) as the study by Seralini’s team. “The 2004 study by Hammond (Monsanto’s) used marginally more rats in the relevant control group, but was in my opinion less powerful statistically because of the inclusion of ‘reference’ control lines that were not fed on the near-isogenic non-GM diet,” says Heinemann who heads the independent Centre for Integrated Research in Biosafety.

But the voices of reason have been few in this current controversy which has redrawn ever more sharply the battle lines in the GM controversy. In the US, the Council for Biotechnology Information, which speaks for the industry, describes the paper as “a bizarre study by French researchers”. It has put out a statement, among others, by Bruce M Chassy, professor emeritus of food science at the University of Illinois, as saying: “It is a well-planned and cleverly orchestrated media event. The study was designed to produce exactly what was observed and it was deliberately allowed to continue until grotesque and fear-evoking tumors developed.”

A clearly annoyed Seralini points out that to get official approval for commercialisation of NK603, Monsanto studied just 10 rats per group and used the same kind of rats. “If 10 rats is too small a number per group to reach a conclusion on safety like some of my critics are saying then NK603 and most agricultural GMOs should be forbidden.”

But while scientists are involved in increasingly acrimonious exchanges, governments have acted. Russia, for one, has temporarily suspended the import and sales of NK603 maize until the country is reassured about its safety, the consumer safety watchdog Rospotrebnadzor announced within days of the paper’s publication. It asked scientists at Russia’s Institute of Nutrition to review the study by Seralini et al and sought the comments of the European Commission on it.

France, for its part, ordered its food-safety agency Anses to quickly review the study and the Prime Minister pushed up the ante by declaring that his government would seek an immediate ban on the EU imports of the Monsanto product if the study’s findings were found conclusive. He put the scientific validation on fast track, demanding “a fast procedure, about a few weeks, to verify the scientific value of the study”.

India is interestingly poised in this controversy. Two years ago, the regulator of the Genetic Engineering Appraisal Committee gave permission to Monsanto India to conduct bio-safety research trials (second year field trial) on two GM maize hybrids: Hishell and 900M Gold containing stacked events MON 89034 & NK603 at several state agricultural universities. Those trials are over and the company is reportedly awaiting approval for commercial release. Is the regulator taking note of the global uproar over the latest toxicological study?

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  • We were in Hyderabad at the

    We were in Hyderabad at the Meeting of Parties (MOP) of the Convention on Biological Diversity (CBD) when this paper was presented by Dr Masange. As a very concerned person, I found that one pointer which was clear from this study is that the present protocol for toxicological studies and feeding studies to approve GM crops were totally inadequate.

    While the rage of controversies and debates can continue, it will be good to not loose sight of the indicator. That the 90 day study period is simply not enough and a long term study is clearly necessary. Moreover, from a layman point of view, is it not common sense that if this is available commercially ( god forbid ), then will we all not be eating this for life time and not for 90 days or extending the rats age to human age argument , even for a few years. We will be eating this for the rest of our lives...So long term studies and conditions as near as our consumption patters need to be the the logic for testing all GM crops.

    But this also brought to the fore one more issue - that Monsanto and their likes continue to lie to the public regarding their studies and safety assessments, and that Govts all over the world eat this lie, obviously with lots of money thrust into their mouths. We in India know this best, because of the nearly two years of fight by a few concerned people in the courts just to get the data of safety assessments of Bt Brinjal out in the public domain. And when it did finally come out, it was cleary discovered ( thanks to independent scientists ) that they had fudged their interpretations. And then it is history. Bt Brinjal was placed under moratorium.

    So Seralini's rats (hapless creatures, though they are ), I hope, will ensure that man, the luckier species, is saved from this dangerous food crop and its serious health impacts.

    Posted by: Anonymous | 8 years ago | Reply
  • When this article was put for

    When this article was put for discussion on The New York Times/Science/Environment - Dot Earth blog, the blogger added that Russian government stopped this maize seed entry to Russia. Today I saw a report in saying that in tribal areas two GM maize companies are secretively - illegally growing seed. In fact this is way the seed companies are contaminating biodiversity rich zones. The groups associated with this clandestine activities are groups proclaimed as farmers friends. They are flourishing in Andhra Pradesh, Karnataka, Maharashtra and Gujarat. They also entered in to Agriculture ministry at the centre and state level. Unless we put such people behind bars, there is no way stop such illegal activities by multinational GM companies. Also, such companies must be blacklisted.

    Dr. S. Jeevananda Reddy

    Posted by: Anonymous | 8 years ago | Reply
  • India must conduct long term

    India must conduct long term trials on its own.

    Posted by: Anonymous | 8 years ago | Reply
  • I am shocked that this

    I am shocked that this article calls Seralini a "highly regarded scientist." All five of his studies on feeding GM food to rats, including this one, have widely and soundly criticized by food safety and regulatory authorities around the world, including those in Europe and Australia/New Zealand, each of which is rigorous and very concerned the safety of GM food. This "report" says nothing of that. Shamefully bad journalism.

    Posted by: Anonymous | 8 years ago | Reply
  • This comment triggers me to

    This comment triggers me to write again. If you think this article is a shock, so is the study and findings. If nothing else, this study simply demonstartes that we need long term - as near life long as possible - studies to be conducted for feeding, as well as other toxicological impacts. Every scientist worth the name knows that cancers, endocrine disruptions, teratogenic effects, mutational impacts do not happen overnight nor can it be found in 90 days. So, when such possibly dangerous products, produced from unnatural processes are to be given to public, its better to go for such detailed investigations.

    Now are you saying that this study was bad, because some one decided to do a long term study and found some adverse impacts.

    And by the way who are you to say that ? Anonymous writer ?

    Posted by: Anonymous | 8 years ago | Reply
  • I am not surprised that this

    I am not surprised that this comment is anonymous. It’s not easy to attack a scientist who has published over 100 peer-reviewed scientific articles and has been a member of two French government commissions that oversaw risk assessment of GMOs. Most of the scientists who have been critical of Prof Gilles-Eric Seralini have been unable to hide their commercial interest in championing short-term industry studies. If Seralini is a bad scientist then so must be the many others, all scientists with impeccable credentials, who have found merit in his study and called for further research to validate his findings. Is Paul Deheuvels, member of the Academy of Sciences who confirmed that Seralini’s methodology is statistically sound, also to be trashed? He has said clearly that Seralini’s research methodology is statistically sound. No one is claiming the study conducted at the University of Caen is the last word on GM food toxicity but in terms of the length of study and the parameters examined it goes far beyond what industry has carried out for regulatory approval of the crops. As for dismissal of Seralini’s studies by regulators, is it really necessary to regurgitate the innumerable instances and reports that have shown regulators (US FDA, European EFSA) are shockingly compromised by their ties to industry? In the related interview with Michael Antoniou which is part of the story, I have pointedly referred to EFSA’s rejection of the Seralini study. Do read it. Unlike scientists who appear to have abjured objectivity in favour of ideology and their narrow interests journalists can only report and do not take sides. And that is what the Down To Earth story is: a report of what Seralini’s study reveals, what Monsanto, the company whose product he has studied, says and what scientists on both sides of the divide have to state. If we do have a vested interest to protect it is the wellbeing of people, animals and the environment.

    Posted by: Latha Jishnu | 4 years ago | Reply
  • I thought I would leave a

    I thought I would leave a comment about the issue of financial interests. Seralini is quoted saying that the scientists criticizing him must be acting out of their own financial interests. Commenters here are also throwing out the financial interest card, however, the article and discussion makes a glaring omission. What are Seralini's financial interests? Who funded the study?
    It turns out that the study was funded by grocery stores and food manufacturers (about 50 of them) who have a financial interest in selling competing products - non GMO foods. In the book that he published at the same time as this study, Seralini bragged about how he hid this funding by channeling it through a non-profit organization, however numerous stories and quotes now exist that attest to the funding sources for this study. Where is the consistency?

    Posted by: Anonymous | 8 years ago | Reply
  • Monsanto, Dupont, Pepsico,

    Monsanto, Dupont, Pepsico, Coca Cola, Kellogg, Mars,
    BASF, and Bayer have been pouring millions of dollars into campaigning against Proposition 37, an initiative that will be on the California ballot on election day and would make it mandatory to label genetically modified food.

    If GM food is indeed safe, corporates should go ahead on their own and mention this on the packaging.

    Posted by: Anonymous | 8 years ago | Reply
  • I wish to repeat here - there

    I wish to repeat here - there are scientists and even agencies that are rejecting this study. What part of the study are they rejecting. Whatever you reject, the main concern that has been raised - the need to conduct long term studies for toxicological impacts, and feeding studies - cannot ans should not be contended.

    Seralini's study, if read with an unbiased mind clearly demonstrates that there are enough reason to review the present protocols for biosafey studies and also present assumptions such as "substantial equivalence". Its ironical and very biased to say that this study is 'inadequate" and hence we dont need such studies and review. That position is more anti-science than the contention that Dr Seralini may not have used the right methodology.

    The science of the methodology used etc can continue to be debated, but that does not give us the reason for avoiding a review of the protocols and have more stringent studies and long term studies,

    Posted by: Anonymous | 8 years ago | Reply
  • long term studies by

    long term studies by independent scientists, not influenced by selfish financial commitments is the best way to assess the safety of GM Foods.-Dr Rajamohan

    Posted by: Anonymous | 8 years ago | Reply
  • "Rats that fed on NK603 or

    "Rats that fed on NK603 or given water containing Roundup died much earlier than the rats in the control group and developed hormonal and sex-related effects"

    Fig 1. of the paper shows higher mortality in the non-GM control group for male rats than in all but one of the GM and Roundup test groups. Therefore the above statement is just not true.

    Having said that there is no statistical significance to any of the results at all so I guess it's immaterial.

    Posted by: Anonymous | 8 years ago | Reply
  • I agree completely. But till

    I agree completely. But till then we do need to freeze commercial cultivation and open field trials...

    Posted by: Anonymous | 8 years ago | Reply
  • i do not understand the need

    i do not understand the need to accelerate a research outcome for market consumption. We should ask the important question if there is really a pressing demand for the commodity that it cannot be handled by existing technology. The problem with technological innovation in the food and health sector is that it is so cheap, easy(read unaccountability of risk) to introduce into the market. If there is no political will to check this, it can create catastrophic, irreparable damages, for example the thalidomide crisis.

    Posted by: Anonymous | 8 years ago | Reply
  • hi everyone and mr.

    hi everyone and mr. sridhar,

    please notice that the anonymous pro-monsanto/gmo posters are either from monsanto or pseudo-experts paid by monsato (unortunatley most of them are sitting within the indian and other national governments).

    Posted by: Anonymous | 8 years ago | Reply
  • similar studies were once

    similar studies were once published by the french and the austrian governments (on MONSANTO GM MAIZE). soon after the release of the research papers the french had withdrawn it. the austrian paper was around for a while on the public domain, and too disappeared.

    the tricky question is, who intervened to pull back the research papers by the authorities?

    Posted by: Anonymous | 8 years ago | Reply
  • I support Mr. Gilles-Eric

    I support Mr. Gilles-Eric Seralini completely. First of all we need to ban all GM Crops till then confirmation of study on it by the scientist that these are safe or not.

    Posted by: Anonymous | 7 years ago | Reply