UPDATE: On Tuesday, Gilles-Eric Séralini responded by email to the criticisms in this post. Mostly, he says, the answers can be found in the study itself. But where he has addressed these criticisms in particular, we have included that below in italics. Séralini stresses that while the data he had available was limited, his findings show that you can’t say these GM corn varieties are safe enough to put on the market and authorize for human consumption right now.
On Wednesday, we covered the overreaction by a few important online sources to an International Journal of Biological Sciences article claiming to find “signs of toxicity” in three varieties of genetically modified (GM) corn produced by Monsanto. We posted some caveats that made us uneasy about the study, such as the funding sources, the unknown quality of the journal, and the fact that the toxicity claims rely on reinterpreting statistical data that Gilles-Eric Séralini and his coauthors themselves note is not as robust as it needs to be.
Karl Haro von Mogel, a University of Wisconsin Ph.D. student who works with Pamela Ronald (the GM expert we quoted in our last post), responded with some other problems he has on this study. He has a blog post of his own (in which he gets hopping mad at coverage that attributed organ damage, organ failure, or even cancer to the rats in the study). But here are the major issues he points out to DISCOVER:
1. Cherry-picking. “They were picking out about 20–30 significant measurements out of about 500 for one of the sets of data they analyzed,” Haro von Mogel tells DISCOVER. “At the 95% significance level, you would expect that 5% of the observations would show a significant difference due to chance alone, which is what happened.” In other words, one would expect to get some alarming results in approximately 25 out of the 500 of the measurements, which is indeed what they found. “Picking apart what seems to be normal background variability seems to me to be data dredging.”
Séralini: We have not chosen the significant measurements, we have listed all the parameters disturbed, all indicated by stars (see Tables joines), there are 20 on 60 for NK603, 15/60 for MON 810 and 23/60 for MON 863 (other paper published in 2007). This is a lot, concentrating mostly on liver and kidneys, the major organ reacting in case of chemical intoxication by food.
One must understand that there are the only blood mammalian analyses allowing the commercialization of these GMOs in the world, these tests lasting only three months and kept secret for the crude data before our study.
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