A French study that claimed genetically modified maize and herbicide caused cancer, organ damage and early death in rats has been dismissed as "of insufficient scientific quality" by the European Food Safety Authority.
Publishing its preliminary findings today, EFSA said it saw no need to re-examine the safety of the maize involved, Monsanto's NK603, because the controversial French research
The study, which attracted widespread attention earlier this month, showed that rats fed a diet of the GM maize and exposed to Monsanto's weedkiller Roundup developed large tumours, suffered liver and kidney damage, and died earlier than a control group.
One of the scientists, Gilles-Eric Séralini, described it as the "longest, most detailed study ever carried out" on the subject, but it attracted criticism for some aspects of its methodology and was labelled as a "scare" tactic by the biotech industry body EuropaBio.
Today, following an initial review, EFSA concluded that the paper was of "insufficient scientific quality to be considered as valid for risk assessment" and that "the design, reporting and analysis of the study, as outlined in the paper, are inadequate".
The European Union agency, whose role is to assess the safety of food and feed on behalf of the EU, added in a statement that it was "unable to regard the authors' conclusions as scientifically sound" and therefore did "not see a need to re-examine its previous safety evaluation of maize NK603".
A number of problems were identified by EFSA, including that the type of rats used were naturally prone to tumours, the number of animals used did not meet international standards for scientific studies, no data was given on the composition and storage of the food provided, and there was no clear reporting of the rats' exposure to the herbicide.
Peter Bergman, who led EFSA's review, 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." The agency said it would conduct a second analysis to be completed by the end of this month, taking into account any additional information provided by the authors of the study.
Séralini had earlier claimed it was inappropriate for EFSA to carry out the review because its role in giving the green light to this type of GM maize for use in Europe amounted to a conflict of interest. He also criticised regulators for relying on three month studies, noting that the effects found in his two-year research would not have been revealed in that timeframe.
Greenpeace's Marco Contiero said: "EFSA recognises that appropriate methodology is crucial for serious scientific research, but omits to mention the fact that no agreed methods currently exist to carry out comprehensive testing of long-term exposure to GM food. This is why suitable methodologies must be developed and the French study should be replicated according to these agreed methods."
Meanwhile Christoph Then, from the think-tank Testbiotech, said it would be wrong to dismiss the study because of the errors cited by EFSA. "As long as there are no new data showing that the French researchers are completely wrong, it would be irresponsible to set aside the outcomes of the French study just because of some methodological deficiencies.
"Even if this study is not considered to be final evidence of health hazards caused by genetically engineered plants, the burden of proof is now with industry. They have to show that their products are safe."