The EFSA assessed the paper against recognized good scientific practices, such as internationally agreed study and reporting guidelines.

Mr 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."

The director of Scientific Evaluation of Regulated Products added that the consideration of possible long-term effects of GMOs has been, and will continue to be, a key focus of EFSA's work to protect animals, humans and the environment.

EFSA's preliminary review issued is the first step in a two-stage process. A second analysis will be delivered by the end of October 2012. This will take into account any additional information from the study authors, who will be given an opportunity to supply study documentation and procedures to the authority to ensure the broadest possible understanding of their work.