I abhor the exploitative practices of Monsanto and companies like it. But truth is more important than politics, and I am always going to speak out when I see false information being touted as “science” to further an agenda.
I wanted to make this clear because I seem be writing a lot about the misrepresentation of GMOs as being harmful to your health. This article (“GMO feed turns pig stomachs to mush”) is by Natural News, which is emphatically NOT a scientific publication. It’s a site with a definite bias, and implies that people who disagree (I guess that means me?) are “paid online trolls, on-the-take ‘scientists.'”*
Natural News is a complete goofball pseudoscience website, but could the study they cite (Carman et al. 2013: “A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet.”) be the first legitimate evidence that GMOs are harmful to health?
It’s published in the peer-reviewed Journal of Organic Systems, which I’m not familiar with, so I looked it up on PubMed, a government database of major journals:
Not being indexed on PubMed isn’t necessarily a sign that a journal is fraudulent, but it’s definitely a warning sign that it’s not a journal of any significance or influence. Wouldn’t a find of this magnitude, purportedly overturning the ‘dogma’ of GMO safety, be published in a major journal? (Answer: it would, if it were legitimate).
The big question motivating this research is: Are GM crops safe for mammals to eat?
Carman et al. assessed the effects of a GM diet on pigs (84 fed GM foods, 84 controls) for 22.7 weeks. Blood draws to assess toxicity were performed two days prior to slaughter; after slaughter the organs were assessed by veterinarians.
The authors reported finding:
-“No difference in disease status of organs between the two groups of pigs” except for inflammation.
-Inflammation was found in both groups of pigs.
-Non-GM fed pigs showed more inflation in the “mild” and “moderate” range.
-GM fed pigs showed more inflammation in the “severe” category.
-No statistically significant difference between the two groups was observed in blood toxicity levels measured.
Carman et al. concluded that “Pigs fed a GMO diet exhibited heavier uteri and a higher rate of severe stomach inflammation than pigs fed a comparable non-GMO diet.”
Looking with a reviewer’s eye, right away I noticed that the authors are cherry-picking studies to support their intended outcomes. They don’t mention the serious methodological flaws that invalidate the Séralini study, nor did they reference all the studies showing the safety of GM foods (eg here and here). If I were a reviewer, I’d send the paper back to the authors to revise based on this alone. Understand that it’s important to thoroughly review all the literature, not just that which supports your position, and note all areas of disagreement. To do otherwise in a scientific publication is biased and misleading.
In addition to the literature review, there are methodological flaws. First of all, the authors only show stomachs from four selected pigs out of the 168 study pigs, in this figure:
Why is this a problem? It’s quite possible that they’re picking the best stomachs of the control group and the worst stomachs of the experimental group to show. This is a very common practice with bad papers–it would be more appropriate to upload images of ALL the stomachs as online supplementary data, or at least show many more examples. Four is simply too few to be honestly representative of all the data.
As for their claims of GM food causing inflammation, they haven’t followed the standard methods for this type of research and this may have introduced some series biases into their analyses. You can’t detect inflammation based on the color of the stomach lining, as the authors did:
“it was incorrect for the researchers to conclude that one group had more stomach inflammation than the other group because the researchers did not examine stomach inflammation. They did a visual scoring of the colour of the lining of the stomach of pigs at the abattoir and misinterpreted redness to indicate evidence of inflammation. It does not. They would have had to take a tissue sample and prepare histological slides and examine these samples for evidence of inflammatory response such as white blood cell infiltration and other changes to determine if there was inflammation. There is no relationship between the colour of the stomach in the dead, bled-out pig at a slaughter plant and inflammation. The researchers should have included a veterinary pathologist on their team and this mistake would not have happened. They found no difference between the two experimental groups in pathology that can be determined by gross inspection.”–Robert Friendship, quoted in Terry Daynard’s blog
There are some serious problems with the methods the authors used to analyze the data as well. Statistical analyses are crucial in scientific research; they’re only way of separating out credible differences from those due to chance alone. Put simply, authors used inappropriate statistical methods for analyzing this type of data.
As Mark Lynas puts it (emphasis mine):
You can immediately see how the data is all over the place from the previous results, which also rule out any causal mechanism with GMO feed – if GMO feed is causing the severe inflammation, why is the non-GMO feed causing far more mild to moderate inflammation? It’s clearly just chance, and all the pigs are not doing well and suffering stomach problems: about 60% of both sets had stomach erosion.
Here is an explanation of what they did wrong, and a re-analysis of the data using more appropriate methods.
Even if we pretend that the authors conducted the study using appropriate measures of inflammation and appropriate statistical methods, you still can’t conclude from these data that GM food causes inflammation.
The ONLY statistically significant difference is in the category of ‘severe inflammation’; there are actually more total cases of inflammation among the non-GM fed pigs. There’s no dose-dependent effect.
So this study still doesn’t support hysterical comments made by Natural News and other anti-GMO activists about adverse health effects caused by GMOs. The reason these studies are so badly designed is that they aim from the beginning to obtain a particular result. Not only is this practice incompatible with conducting rigorous science, it also violates all basic standards of care for ethical animal research:
My judgement is that, as with Seralini, this study subjects animals to inhumanely poor conditions resulting in health impacts which can then be data-mined to present ‘evidence’ against GMO feeds. Most damning of all, close to 60% of both sets of pigs were suffering from pneumonia at the time of slaughter – another classic indicator of bad husbandry. Had they not been slaughtered, all these pigs might well have died quickly anyway. No conclusions can be drawn from this study, except for one – that there should be tighter controls on experiments performed on animals by anti-biotech campaigners, for the sake of animal welfare. —Mark Lynas
Are you comfortable with shoddy and ethically questionable research being conducted to prove your “side” right?
It’s particularly easy to accept information touted as “scientific” if it happens to fit with what you believe anyway. It is very, very hard to accept that what you believe might be wrong when evidence shows it. But you must. If I discover tomorrow that a result or interpretation I’ve published is incorrect, I will definitely feel embarrassed, but I will try not to stubbornly insist that I’m right in the face of convincing evidence. If I did, my work would be based on the tools of faith, not science. There’s no difference when approaching contentious political/social issues; you can’t claim the mantle of scientific research when you don’t follow scientific methods. I’m always in favor of MORE research on this subject. But if you’re a GMO critic, I strongly suggest that you demand that researchers follow the accepted and standard practices of the field in their data collection and analysis methods, as well as the highest ethical standards when it comes to animal research.
I want to close by reiterating that while there are some extremely valid criticisms of Monsanto and similar corporations, the best research out there does not show GM food to be unsafe. Remember:
“If it disagrees with experiment, it’s wrong.”
No matter how you might wish it to be otherwise.
*In case it’s not obvious, I don’t make a dime from any corporation, least of all Monsanto.
References and further reading:
“A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet.” Judy A. Carman, Howard R. Vlieger, Larry J. VerSteeg, Verlyn E.Sneller, Garth W. Robinson, Catherine A. Clinch-Jones, Julie I. Haynes, and John W. Edwards. Journal of Organic Systems, 8(1), 2013
Published criticism of the Séralini study (behind a paywall, unfortunately, but if you’re really eager to read it, get in touch) http://www.ncbi.nlm.nih.gov/pubmed/23430588
Here are a few other perspectives on the methodological flaws in this study if you’d like to learn more: