According to Vendomois et al, 2009:
these data highlight signs of hepatorenal toxicity, possibly due to the new pesticides specific to each GM corn.
Monsanto, the manufacturer of two of the studied strains of GM corn, responded, dismissing the article, particularly by criticizing the statistical methods used. Is Monsanto's criticism valid?
Have there been additional studies done that either support or refute the claim that genetically-modified corn has toxic effects?
The simple answer is no.
GM corn has the BT gene that allows lower use of pesticides due to increased or the RR gene that allows the use of glyphosate for weed control. Neither of these alterations have any impacts upon the production of sugars or proteins in the plant. http://en.wikipedia.org/wiki/Genetically_modified_maize http://www.ca.uky.edu/entomology/entfacts/ef130.asp
The problem that can arise is from the pesticides that are now used on the crops and the timing of their application. These pesticides are known to harm mammals and if the dose is high enough can cause problems. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2793308/
Generally though, because you are removing pests and weeds the plants tend to be healthier so they are less impacted by pathogens, thus better for consumption. http://www.acsh.org/factsfears/newsID.962/news_detail.asp
There is an issue with using corn as a feed supplement in animals though. Corn is not a complete food source and is generally low in protein, especially tryptophan. This means that a feed mix is required, not just straight corn meal. http://www.ag.ndsu.edu/pubs/ansci/beef/as1238w.htm
Another issue is that corn can cause Pellagra. This is due to the niacin and B12 being bound in the corn starches and not being released in normal digestion. Tryptophan is also low in corn and can cause Pellagra. http://en.wikipedia.org/wiki/Maize#Pellagra
http://en.wikipedia.org/wiki/Pellagra
So the problems often cited with GM corn are actually just problems with corn itself. Neither are harmful, if used correctly in a balanced diet, but pesticide residues are of concern. For more see this: http://onlinelibrary.wiley.com/doi/10.1046/j.0960-7412.2002.001607.x/full
We don't know the long term effects that it might have. Feeding studies are generally 90 days long (and most are done by Monsanto, if you trust in the first place).
You also can't simply look at the specific protein produced by the transgene, as introducing a transgene affects the entire phenotype.
Monitoring the pattern of gene expression using microarray technology showed that mRNA levels for 5% of the genes were significantly upregulated or downregulated. Recent studies in transgenic plants showed that the over-expression of a gene involved in pectin synthesis had no effect in tobacco, but caused major structural changes and premature leaf shedding in apple trees [4]. Although these sorts of unpredicted changes in gene expression and function are frequently observed, they have received very little attention. Furthermore, they are not unexpected. The maintenance of a specific cell phenotype involves a very precise balancing act of gene regulation, and any perturbation might be expected to change the overall patterns of gene expression. The problem, as with secondary modifications, is that there is currently no way to predict the resultant changes in protein synthesis."
- Source: Commentary, A different perspective on GM food, David Schubert, Nature Biotechnology 20, 969 (2002) doi:10.1038/nbt1002-969
The simple answer is there is no simple answer. It is not appropriate to unequivocally say "no".
The FDA has stated they are not in the business of policing; rather, they put the onus on the seed corporations.
One only needs to look at history to have some serious questions and concerns. Sure genetic engineering hasn't been around very long so one would need to look at the biggest players in the Genetic Engineering Industry. Monsanto & Dow Chemical two chemical companies with an awful track record.
Yes Monsanto IS a big part of GE Food and wields power and influence like Big Tobacco in the 1970s. They do patent seeds and they now own an estimated 25% of the world seeds due to acquisitions. If you don't know about Monsanto's history check out the Monsanto Controls Your Diet article in Salon Magazine's April 2013 issue. Since 1901 they have been making chemicals that poison. Here is a link to the latest study showing a link of GMO food to leukemia
Yes, each study such as this is refuted by 100 Monsanto, Sygenta, etc. supported/funded studies. It is tough to put trust into studies from Univ. of Florida for instance that receives so much from Sygenta. I do not consider any such studies objective. For decades the tobacco industry did the same thing.
Whenever something is so one-sided (and the power and future profits are on that side) I often find myself skeptical. I am by no means against genetic engineering.
