The EFSA criticised he study for selecting tumour-prone test rats, and for failing to obey key international research protocol. The EFSA said its findings were based on details in a paper produced by the test team, French scientist Gilles-Eric Séralini and his team at the University of Caen, France.
As a result, the EFSA concluded that the study’s concerns about maize NK603 and the herbicide — both of which are commonly used in EU food production — were of insufficient scientific quality to be considered as valid for risk assessment.
The authority’s initial review found that the design, reporting, and analysis of the study by the French researchers were inadequate. The EFSA has invited the paper’s authors to share key additional information before it can declare the study as “scientifically sound”.
Among key initial findings, EFSA found that the strain of rat used in the two-year study is prone to developing tumours during their life expectancy of two years.
The EFSA said: “The observed frequency of tumours is influenced by the natural incidence of tumours typical of this strain, regardless of any treatment. This is neither taken into account nor discussed by the authors.”
EFSA also criticised the protocols used. The authors split the rats into 10 treat-ment sets but established only one control group.
This meant there was no appropriate control for four sets of test rats — 40% of the animals — all of whom were fed GM maize treated, or not treated, with a herbicide containing glyphosate.
Per Bergman, who led EFSA’s work, said: “Some may be surprised that EFSA’s statement focuses on the methodology of this study rather than its outcomes; however, this goes to the very heart of the matter.
“When conducting a study it is crucial to ensure a proper framework is in place. Having clear objectives and the correct design and methodology create a solid base from which accurate data and valid conclusions can follow. Without these elements a study is unlikely to be reliable and valid.”
In an interview with AFP, Mr Séralini said he would not give the EFSA any additional information until it first detailed the basis of its own assessment.
“It is absolutely scandalous that [EFSA] keeps secret the information on which they based their evaluation of NK603 and the pesticide. In any event, we will not give them anything. We will put the information in the public domain when they do.”
Mr Séralini and his team say their experiment in GM food is the first to follow rats through their lifespan, as opposed to just 90 days, but other, non-EFSA experts have also questioned its methodology, results, and relevance to humans.
Maize NK603 was developed by Monsanto to make it resistant to the herbicide containing glyphosate, the Monsanto product Roundup, enabling farmers to use the weedkiller just once in the crop’s life cycle.
In May, the EFSA also said a temporary French ban on another Monsanto corn, MON810, was not properly based on scientific evidence.
“Based on the documentation submitted by France, there is no specific scientific evidence, in terms of risk to human and animal health or the environment,” EFSA said of the French position on the second GM trial.
Last week, French prime minister Jean-Marc Ayrault vowed to seek an immediate EU ban on imports of a GM maize developed by Monsanto had the study linking it to cancer in rats been deemed credible.
Mr Ayrault said: “I’ve demanded a rapid procedure, in the order of a few weeks, which will allow us to establish the scientific validity of this study. If the results are confirmed [agriculture minister] Stephane Le Foll will seek a European ban on these [GM organisms].”