The study that was released last month by a French research team headed by Professor Gilles-Eric Séralin was the first to find that genetically modified (GM) corn produced tumors in rats. It was published in the journal Food and Chemical Toxicology. But the European Food Safety Authority has released a statement saying that the study did not conform to standard study protocols and the organization is “unable to regard the authors’ conclusions as scientifically sound.”
The criticisms focus on the methodology of the study instead of the results. All scientific studies must adhere to a certain methodology in order to produce results that are replicable, clear, and free of bias. The EFSA is planning to release a second review at the end of this month which will include additional information from the study’s authors.
This study directly refutes the Monsanto study that found the Roundup Ready Corn was safe for human consumption. That study followed the animals for 90 days. Séralin’s study found that the rats developed tumors after four months of being fed the GM corn. The criticisms of the study and Dr. Séralin’s responses as published by Sustainable Food Trust include several points.
First, the strain of rat, the Sprague Dawley rat strain, used in the study is prone to developing tumors over their two year life expectancy, which was not discussed by the authors. Dr. Séralin says they used the same rats that were used in the Monsanto study and that the SD rat cancer pattern accurately mirrors that of humans. Furthermore, that rat strain is an “excellent human-equivalent model for long-term carcinogenicity studies.” Second, the sample size of rats was too small to reach statistically significant conclusions. Dr. Séralin responds that Monsanto used the same number of rats in their study.
Third, the study only had one control group, even though there were ten treatment sets. Dr. Séralin says that the control group parameter is the same as used in industry, and that there are large differences in tumor frequencies between the control and experimental groups. In fact, the differences are so large there was no need to conduct statistical tests. Fourth, the tumor rates did not increase in line with the dose of GM foods fed to the animals. Dr. Séralin says that this is not a “regular poison effect”, but hormonal system disturbances, which display nonlinear effects.
The main conclusion of the paper is that the Monsanto study only lasted for 90 days, and the French study found tumors developed after 120 days. The study’s authors did stress that more research, in longer time frames, needs to be conducted to reach solid conclusions.