Dr Hayes misunderstands or misrepresents the Séralini study as a flawed carcinogenicity study, when in fact it is a chronic toxicity study that meets internationally accepted norms for this type of study. When this false assumption is corrected, the claimed reasons for retracting the study vanish.

IN SEPTEMBER 2012 a pioneering study was published in the journal Food and Chemical Toxicology, published by Elsevier. The study was conducted by a team led by Professor Gilles-Eric Séralini at the University of Caen, France. It investigated the long-term effects of feeding a genetically modified (GM) maize, called NK603, and low levels of Roundup, the herbicide that the maize is engineered to tolerate during cultivation, to rats.

Séralini’s long-term (chronic) toxicity study reached two key conclusions. Rats fed GM maize NK603 and low levels of Roundup herbicide over a long-term 2-year duration showed severe organ damage, specifically to the kidneys, liver and pituitary gland, as well as hormonal disruption. These effects were seen in rats fed the GM maize alone and in those fed the GM maize in combination with Roundup, as well as in rats given low levels of Roundup alone in drinking water.

Of equal importance was the timing of onset of these effects, which occurred after the 90-day cut-off point of the studies that the industry conducts on its own GM crops in support of regulatory authorization.

The study also unexpectedly found increased rates of large palpable tumours and mortality in most treated groups of rats. Both trends were reported in the paper, as is the norm for toxicology studies, but were not further analyzed. No statement or inference was made regarding cancer.

In a follow-up paper also published in FCT, the authors explicitly acknowledged that a separate, dedicated study complying with the norms for carcinogenicity (cancer) studies and using larger numbers of animals would need to be carried out in order to draw firm conclusions on the tumour findings.

Nonetheless, in November 2013 the editor of FCT, Dr A. Wallace Hayes, took the unprecedented step of retracting the Séralini study more than a year after it was published. The retraction occurred within months of the arrival of a former Monsanto employee to fill a newly created editorial position in biotechnology at FCT.

The reason given for the retraction was the inconclusiveness of the mortality and tumour findings. Dr Hayes alleged that the authors had claimed a “definitive link” between the treatments under test – GM maize and Roundup – and cancer, adding that this conclusion was not justified, given the small number of animals per group used in the study. Dr Hayes acknowledged that this number of animals may have been appropriate for toxicity but not for carcinogenicity studies.

The logic of this argument strains credibility, given that Séralini's study – as stated in the title of the paper – was a chronic toxicity study, not a carcinogenicity study, and that the authors made no definitive claim or inference regarding cancer.

The issue of inconclusiveness is problematic on several grounds. Inconclusiveness is not a valid reason for retracting a study, according to the norms of scientific publishing to which FCT subscribes. Conclusiveness is, in fact, rare in scientific studies. Applying the previously unknown criterion of mandatory conclusiveness for publications would oblige the retraction of many scientific papers. That this has not happened supports the conclusion that Séralini’s study has been assessed based on double standards not applied to other papers.

Moreover, it is unacceptable to retract an entire study on the grounds of inconclusiveness of just two of several aspects of the study. Dr Hayes has erased from the scientific record the statistically significant and solidly based toxicological findings of organ damage along with the observations of tumours and mortality, even though he has not contested the former.

By retracting this paper on scientifically indefensible grounds, Dr Hayes has erased potentially critical findings affecting public health. The authors of this article call upon Dr Hayes to formally reinstate the Séralini study within the pages of FCT and to provide a full public apology to Professor Séralini and his team.