Turns out Seralini’s paper isn’t the first long-term study of GM-feed on rats. Another one was done and published in 2008. Unfortunately, it’s in Japanese. Here’s the abstract and data report.
I have the data table here:
Now this is how to do this study. Note that there are 2 male test groups and 2 female test groups and then the controls. Yet over 250 animals were used.
Non-GM in this case was fed 30% non-GM soybeans. The GM group was fed with 30% GM soybeans. The CE-2 groups were the controls fed 100% commercial rat diet.
The rats used in this study were F344 DuCrj Rats. If anyone has a link to a supplier of this species, let me know.
Now, take a good hard look at the data table above. Compare to Seralini’s data results here.
This study examines the different types of cancers, which groups had them, and in what frequency. I’m not going to do a full analysis, you can do that, but I would like to point out a few things of note.
In the female group, the commercial diet group had the same number or more cancers in 4 of the 10 female only groups. The non-GM diet had the same number or more cancers in 5 of the 10 female only groups of cancers. The GM-diet had the most cancers in only 2 of the female only groups. The GM-feed was tied for most in 2 of the groups.
More GM rats survived the study than the non-GM rats and the commercial chow groups. Of course, more of them had tumors too though. But is it statistically significant? I don’t think so. If anyone has an English translation of this paper, I’d love to have a copy.
Again, keep in mind that these rats were fed 1/3 third of their diet, every day for 2 years with GM-soybean. That’s like eating about 700 calories a day in GM-soybean. For those of you curious, a pound of soybeans has about 950 calories. So, this test was the equivalent of you eating most of pound of soybeans, every day for over 700 days.
Based on these conclusions AND Seralini’s, I must agree with the authors of this paper.
There were several differences in animal growth, food intake, organ weights and histological findings between the rats fed the GM and/or Non-GM soybeans and the rats fed CE-2. However, body weight and food intake were similar for the rats fed the GM and Non-GM soybeans. Gross necropsy findings, hematological and serum biochemical parameters, and organ weights showed no meaningful difference between rats fed the GM and Non-GM soybeans. In pathological observation, there was neither an increase in incidence nor any specific type of nonneoplastic or neoplastic lesions in the GM soybeans group in each sex. These results indicate that long-term intake of GM soybeans at the level of 30% in diet has no apparent adverse effect in rats.
Cassandra's Tears 
Are there examples when substances innocuous to rats are toxic to humans? I struggle to see how a two year study on rats would be a safe way to predict a 50 year effect on humans. Is the correlation from past experimental eviden e that reliable?
The reason we can use rats and mice and pigs is that, biochemically, they are exactly the same as humans. There’s a whole area of research into this. I’ll see if I can find some links for you.
One point to keep in mind is that during these 2 year tests, the rats are eating 33% of their entire diet in GM products. That’s roughly the equivalent of you eating 1 pound of GM corn a day, for two years.
There is some evidence to suggest that some of the problems with these types of GM studies isn’t the GM part of the feed, it’s that the rat’s diet is 33% corn (or soybean or whatever) and that is actually having a negative impact on the animals. A properly designed experiment will factor that into account, with control animals receiving 33% non-GM corn. Seralini at least got that right, but in most cases, the control rat groups had more deaths than any of the test groups (I think, I’ll have to look at the data again).
That being said, there is a 20 year study going on right now. Europe has banned GMOs, America has not. So far, after 20 years of that difference, there are no noticeable effects one way or another. There was an incident a few years back when some genes from a Brazil nut were used and caused an allergic reaction in test subjects. The product was pulled and that hasn’t happened since.
BTW: My new blog http://skepticink.com/smilodonsretreat/ has a few more papers about GM research and I’ve got a ton of them to go through and report on.