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expert reaction to republication of Séralini study on Roundup-tolerant GM maize

Environmental Sciences Europe re-published a study retracted from Food and Chemical Toxicology by Gilles-Eric Séralini which purported to show rats fed the herbicide Roundup and Roundup-tolerant GM maize developed cancerous tumours.


Prof Bruce Chassy, Professor Emeritus of Food Safety/Nutritional Sciences, University of Illinois, said:

“The original Seralini paper was rejected for many reasons. Perhaps the most important of these was that the design of the study and the described methods for data collection were fatally flawed in a number of ways. No amount of rewriting or excuses for faults can make the data whole again. When the data are faulty, the experiment must be repeated with proper design and methods.

“Food and Chemical Toxicology and Elsevier have acted poorly throughout this affair. It is difficult for experts to understand why Food and Chemical Toxicology published the paper since it is exceedingly challenging to find an expert peer-reviewer who cannot find numerous flaws in the paper. The journal then consumed more than a year to retract the paper.

“Among the several reasons for retraction that Food and Chemical Toxicology failed to cite was the unethical use of animals in experiments which the Committee on Publication Ethics states in a reason for retraction.

“Seralini now states that the research was not a cancer study. If that is true, then there was no reason not to euthanize animals when tumors were first detectable. There was nothing to gain or learn. This is unethical treatment of animals.”


Prof Tom Sanders, Professor of Nutrition & Dietetics, King’s College London, said:

“Republishing data that was faulty in the first place in study design and analysis does not provide redemption. Furthermore, it is now possible to publish almost anything in  Open Access journals!

“Seralini did not follow conventional methods for assessing animal toxicity and made most of the measurements at the end of life.  When a very large number measurements are made statistically significant differences will occur play of chance.

“The figures of an animal with a large tumour serve no scientific purpose. There are numerous omissions of probabilities which could lead the less critical reader to infer differences that are not statistically significant.”


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

“The article still does not appear to have had proper statistical refereeing, and the methods and reporting are obscure. The claimed effects show no dose-response, and so the conclusions rest entirely on a comparison with ten control rats of each sex.  This is inadequate.”

“The study needs replicating by a truly independent laboratory using appropriate sample sizes.  I agree with the authors that this whole area would benefit from greater transparency of data and improved experimental and statistical methods”


Professor Joe N. Perry, Visiting Professor of Biometry, University of Greenwich, said:

“This paper appears to be based on the same data as Seralini’s previous 2012 paper, with no real new information and only minor rephrasing and a few new references.  Therefore, I doubt whether my conclusions would differ from those of the vast majority of independent members of the scientific community, who concluded in 2012 that there was insufficient evidence to justify the claims of CRIIGEN and Giles-Eric Seralini.  However, I do welcome Seralini’s promise to publish his raw data and my hope is that all organisations involved in GM risk assessment will, wherever possible in the future, publish in full their raw data in the spirit of full transparency and openness.”


Declared interests

None declared


‘Republished study: long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize’ by Gilles-Eric Séralini et al.  published in Environmental Sciences Europe on Tuesday 24th June 2014.

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