Tyson Adams

Putting the 'ill' back in thriller

Is GM corn toxic?

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 their been additional studies done that either support or refute the claim that genetically-modified corn has toxic effects?

Answer:

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://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.

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

Another point that should be made is that the paper cited is from a notorious “research” group who produce shoddy science in order to further their biased agenda against GM technology. The big problem with the paper is that it uses the wrong sort of analysis and the data has already been analysed by two other papers and found to say the opposite of what this paper says. Essentially, if you do a statistical test with a 95% confidence margin, you are saying that you have one chance in twenty of being wrong because of natural variability. So if you measure 20 variables with separate tests, you are likely to have one be a false positive result. Measure 40 with separate tests, 2 false positives. This is what the research group did, set up the stats to generate lots of false positives, instead of analysing the data correctly with tests that account for this problem. It should be noted that this is a common problem/tactic with anti-GM research papers.

Additional question: The ACSH source claims Studies Indicate GM Crops Are Safer and Healthier, but last time ACSH reported their funding, they were co-funded by what are now GMO companies. Currently they are not open about their funding at all. Therefore, their independence cannot be established. Can you back up the claim by research where all funding sources are open and independent? – gerrit

Reply: Of course there is plenty of independent data. gmopundit.blogspot.com/ has an entire series devoted to the safety studies of GM crops. The highly respected journal Nature had an entire edition devoted to the topic. But that is beside the point, the underlying mechanism of the Bt is not one that works on humans (it is even sprayed on organic farms). We don’t have an alkaline stomach to activate the chemical (ditto some insects it doesn’t impact either) which means it can’t do anything. So the concerns are completely misplaced.

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