GM maize and cancer study retracted – experts respond

A controversial study on the effects of genetically modified maize on rats has now been retracted by the publishing journal.

The study suggested that genetically modified glyphosate-resistant corn could cause cancer in rats. The article by Gilles-Eric Séralini and colleagues was published in the journal Food and Chemical Toxicology. The global network of Science Media Centres collected extensive, largely critical commentary on the controversial paper when it was published in September 2012.

A media release from the journal has now announced that, having completed a full investigation, they will be retracting the article. The release stated that the investigation found, “no evidence of fraud or intentional misrepresentation of the data. However, there is a legitimate cause for concern regarding both the number of animals in each study group and the particular strain selected.

“…A more in-depth look at the raw data revealed that no definitive conclusions can be reached with this small sample size regarding the role of either NK603 or glyphosate in regards to overall mortality or tumor incidence.”

You can read more about the retraction in blog posts from SMC Manger Peter Griffin at SciBlogs and University of Auckland Statistics Professor Thomas Lumley on StatsChat.

Our colleagues at the UK SMC collected the following expert commentary. Feel free to use these quotes in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476;

Prof Alan Boobis, Professor of Biochemical Pharmacology at Imperial College London, said:

“Retraction of a scientific article should always be seen as a last resort.  Even when inconclusive, an article can contribute to scientific discourse on a topic.  This is why replication of findings is so important.

“However, there are instances where the conclusions of a paper significantly over-interpret the findings, as was the case here.  Whilst always of concern, this is particularly problematic when the subject of the paper is of considerable public and media interest.  Hence, in the case of the article by Seralini et al I believe that the journal has acted responsibly and appropriately in evaluating all the data and taking this decision.”

Prof Jonathan Jones, Project Leader at the Sainsbury Laboratory, said:

“I congratulate the journal Food and Chemical Toxicology for its level-headed reappraisal of the original decision to accept the Seralini et al paper for publication.  Whatever one’s opinion of the motivations of the authors, all must accept that the suggestion that glyphosate or GM maize can elevate cancer risk is not supported by the experimental data in this paper.”

Prof Dale Sanders, Director of the John Innes Centre, said:

“The careful design of a scientific study is essential for generating results upon which reliable conclusions can be based.  If many studies draw the same conclusions, evidence-based policy can be developed.  Retracting a study that fails to meet accepted standards of reliability is particularly important given the controversy generated in Europe by GM crops.”

Prof Cathie Martin, Group Leader at the John Innes Centre, said:

“The major flaws in this paper make its retraction the right thing to do.  The strain of rats used is highly susceptible to tumours after 18 months with or without GMOs in their diets.  Keeping animals alive beyond their recommended lifespan means the results are inconclusive and also raises serious animal welfare concerns.”

Prof David Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge, said:

“It was clear from even a superficial reading that this paper was not fit for publication, and in this instance the peer review process did not work properly.  But at least this has now been remedied and the journal has recognised that no conclusions can be drawn from this study, so I suppose it is better late than never.  Sadly the withdrawal of this paper will not generate the publicity garnered by its initial publication.”

From the Science Media Centre of Canada:

Dr Alan McHughen, Plant biotechnologist at College of Natural and Agricultural Sciences, UC Riverside,

“The retraction is long overdue. The paper should never have been published in the first place, as it did not, and never has, met the requirements for a scientific publication. For Food and Chemical Toxicology to retract it now simply brings the long discredited study back into the public arena, once again giving it prominence it doesn’t deserve.

“We hope Food and Chemical Toxicology (and other journals) learns not to publish scientifically unworthy studies. Earlier, Lancet published a similar paper not on the basis of scientific value, but because it was a “controversial topic” and the editor wanted to reveal the data to inform the debate. That one backfired, too.”

Prof Cami Ryan, University of Saskatchewan, College of Agriculture and Bioresources, comments:

“For the record, the retraction was justified and I think that I speak for the broader scientific community that this needed to happen. It is disappointing that Seralini didn’t withdraw the article when presented with that option by FCT editors in a letter to him on November 19, 2013.

“The Seralini study had many problems. And, yes, it was discussed (and critiqued) in reputable scientific circles for some time after it was published. Seralini’s results were discredited by food and feed safety agencies all over the world. Retraction seemed inevitable. It was only”a matter of time. We cannot hold progressive and innovative science to such low standards as presented by the Seralini study. I blogged about the Seralini study last year here.”

Robert Wager, Technician and faculty member at the Biology Department at Vancouver Island University,  comments

“I was one of the authors of one of the 16 letters to the Editor of FCT complaining about the Seralini 2012. It is good news that the retraction is about to happen but worrisome it took over a year for the journal to do the right thing. Unfortunately, Seralini will now be viewed as a martyr by the segment of the population that are convinced of the dangers of GM crops and food. The power of pseudo-science to generate fear must not be underestimated. Once instilled, facts rarely dissipate that fear.

“The retraction further confirms the global food safety opinion on the safety of food derived from Genetically Engineered crops. The European Academies Science Advisory Council (members of each countries National Academy of Sciences) 2013 statement: “There is no validated evidence that GM crops have greater adverse impact on health and the environment than any other technology used in plant breeding. “

“The American Association for the Advancement of Science 2012 statement said it best. “Moreover, the AAAS Board said, the World Health Organization, the American Medical Association, the U.S. National Academy of Sciences, the British Royal Society, and “every other respected organization that has examined the evidence has come to the same conclusion: consuming foods containing ingredients derived from GM crops is no riskier than consuming the same foods containing ingredients from crop plants modified by conventional plant improvement techniques.”

“This is the third time Seralini et al. have been severely rebuked by food safety authorities. The same criticisms apply to all three publications by this group: “inadequate design, analysis and reporting, European Food Safety Authority finds that it is of insufficient scientific quality for safety assessment. EFSA 2012

“I would hope the mainstream media is becoming more aware of the continued flaws of most if not all publications that claim harm from GE crops and food. It is not in the public’s best interest to continue to widely disseminate flawed science that is designed to generate fear, not educate. Hopefully the media will contact real experts in food toxicology for a considered opinion before they publish the next anti-GMO industry sponsored publication. Fear generation about safe products does not serve the publics interest.”