New Séralini study questions legitimacy of GM safety data

By Nathan Gray

- Last updated on GMT

New Séralini study questions legitimacy of GM safety data

Related tags Toxicology Genetically modified organism Genetically modified food

The validity of safety tests for commercial pesticides and genetically modified foods has been called into question, after French researchers found control diets and historical diet data contained GM materials and possible carcinogens. 

The new study, which was due to be published in PLoS One ​today**​, tested the contents of dried feeds that are commonly used as control diets for safety tests using laboratory animals - sourced from five continents. The team, led by Professor Gilles-Eric Séralini of the University of Caen, and supported by CRIIGEN, analyzed 13 samples of commonly used rat feeds for traces of 262 pesticides, 4 heavy metals, 17 dioxins and furans, 18 PCBs and 22 GMOs.

According to Séralini, the results were overwhelming – showing that all feeds contained ‘significant concentrations’ of several of these products, at levels likely to cause diseases and disrupt the hormonal and nervous system of the animals.

As a result, the French team warned that historic industry safety data for pesticides and genetically modified foods based on comparisons between these ‘control diets’ and ones containing test materials may be invalidated.

However researchers have suggested that the methods used in the study may themselves be flawed. 

**Editors' Note:The publication of this study has been delayed by PLoS One. Prior to this publication of the study had been widely advertised by CRIIGEN. At the time of writing this story, FoodNavigator believed that the study had been published after seeing documents suggesting an embargo was lifted on at 8pm on 17th June. As it currently stands, we are unaware of a new timeframe for the publication of this study and are waiting to hear from PLoS One on an update on the situation.**

The previous Séralini saga ... 

Professor Séralini and his lab came to prominence after previous research published in 2012 linked the consumption of Monsanto's NK603 GM maize and its associated herbicide Roundup to long term toxicity and cancer in rats​.

At the time, the research received huge media attention, after a series of gruesome pictures of cancer ridden rats accompanied warnings that the products led to a ‘greatly increased’ risk of tumours' and premature death.

But amid heavy criticism​ from many in the scientific community, and rejections of the study by several high profile regulators including EFSA​, the editors of the Food and Chemical Toxicology (FCT) journal where the study had initially been published conducted an investigation in to the study.

In a letter to Séralini dated the 19th November 2013, journal editor Dr Wallace Hayes asserted that the journal board had completed a 'thorough examination' of the data provided to them by the researcher and had expressed many concerns about the quality of the data - ultimately leading to a recommendation that the article should be withdrawn​.

Séralini claimed the decision was based on 'unscientific double standards'​ and sought to have the paper re-published elsewhere. Last year the paper was republished in Environmental Sciences Europe​.

New research

The as yet unpublished new research from Séralini and his team used standard methods and garnered the help of accredited laboratories to test the make-up of animal feeds that have been historically used as control diets in research investigating genetically modified foods – including industry safety data that has led to regulatory approval.

The team reported that residues of pesticides containing glyphosate, such as Roundup, were detected in 9 of the 13 diets, while 11 of the 13 diets contained GMOs that are grown with large amounts of Roundup. 

These dried feed diets, which contain significant amounts of pesticide residue and GMOs that are grown alongside pesticides have been repeatedly used as control diets to validate the safety of genetically modified crops, warned the team – adding that such studies are ‘obviously flawed’.

Fatally flawed? 

While Seralini and his group suggest their findings show that safety studies are unsound, experts and industry have been quick to dismiss the methods used by the group as ‘flawed’ themselves.

Commenting on the study finding, Dr Carl Winter, Cooperative Extension Food Toxicologist at University of California, Davis warned that the study’s conclusions can not be supported – adding that comparing maximum dietary intake with the Acceptable Daily Intake (ADI), as the study did, ‘is not appropriate to demonstrate risk.’

Indeed, he suggested that a more appropriate comparison would be to use No Observed Effect Level (NOEL) from long-term animal toxicology studies - which represent the maximum amount given to laboratory animals on a daily basis that does NOT cause any noticeable toxicity.

"For all of the other seven pesticides detected, exposure at the exaggerated maximum dietary intake level was still below the ADI levels, (commonly 100 times lower than NOEL levels from animal studies), so it is difficult to make a valid case as to how such exposures would cause effects in the animals consuming feed containing pesticide residues,”​ said Winter. “ It should also be pointed out that these were the only pesticides detected out of 262 analyzed.”

"The process of comparing maximum dietary intake levels with ADI levels for other contaminants such as metals and PCDDs and PCBs is similarly misleading."

A statement from Monsanto added that trace levels of various compounds in laboratory feed ‘are not uncommon or surprising’, and “certainly does not imply a feed safety risk. 

“Researchers already use diets that are certified to limit the maximum concentrations of many of these substances in order to be certain no health effects are triggered and that the results of their studies are valid,”​ said the firm.

“This paper irresponsibly misleads readers by insinuating conclusions that the authors did not even study and by calling into question every rodent toxicological study ever conducted - including their own.”

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This is about scientific method

Posted by Brian John,

We can immediately dismiss Monsanto's comments here -- the corporation will continue to protest that the product they market as "The Ultimate Killing Machine" is in fact perfectly harmless. And how Carl Winter has the nerve to pontificate about the study when he has not even seen it is beyond me. Surely the whole point that the authors are trying to make is that studies which purport to demonstrate the safety of a particular GMO and which use contaminated chow for both the control group of animals and the test group are either incompetent or fraudulent. It's that simple. Thousands of scientists will scream and call down hell and damnation upon the French team behind this paper -- but the fact of the matter is that even a 15-year-old in a school lab knows that you do NOT use contaminated feed in your control groups if you are testing for GMO effects, since your end results will inevitably be screwed up.

And shall we give the authors just a little credit here for acting in good faith? If PlosOne gave them a publication date and then changed it at the last minute, whose fault is that?

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Not yet published

Posted by Cin An,

You may want to double check your facts as apparently PLOS One has "delayed" their plans to publish the Seralini claims. In apparent violation of the Journal's guidelines the anti-GMO activist French researcher has made his research claims public regardless. The point of peer reviewed scientific publishing is to do so in such a manner as allows for expert, critical review - particularly when extraordinary claims like these are made as they require extraordinary evidence. As with his past discredited research, this paper again lacks that evidence. And, Mr. Seralini’s preemptive publicizing prior to actual Journal publication adds more fodder to the claims he's more interested in propaganda than actual science.

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no link yet in plos one

Posted by James William,


Right now his website says "Published in PLOS ONE (June 2015) – Link coming soon." [1]

Though a previously cached version of this page [2] shows he had posted a link [3] which is now 404.


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