Source:Carman JA, HR Vlieger, LJ Ver Steeg, VE Sneller, GW Robinson, CA Clinch-Jones, JI Haynes, and JW Edwards. 2013. A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet. Journal of Organic Systems 8(1):38-54.
Updated 9 Oct 2013
In this study, pigs were fed GM or nonGM diets for almost 23 weeks. At the end of the study, the pigs were weighed. Blood chemistry was analyzed, and organ weights were measured. Weight gains and all body statistics were the same for both groups of pigs, but “GM-fed pigs had uteri that were 25% heavier than non-GM fed pigs (p=0.025). GM-fed pigs had a higher rate of severe stomach inflammation with a rate of 32% of GM-fed pigs compared to 12% of non-GM-fed pigs (p=0.004).”Aside from the fact that it is not evident how pigs with severe stomach inflammation could have the same weight gain as pigs with no stomach inflammation, and aside from the fact that commercial pig slaughter houses have not found the same differences, the paper has several other limitations:
The main reasons why this paper fails:
- The researchers used red color to indicate inflammation of the stomach, but red color does not always come from inflammation. Stomach tissues were never tested for inflammation.
- Even if inflammation had been present, it could be due to other factors, such as the grinding the feed too finely.
- A tenet of toxicology states that the dose makes the poison; yet, there were more pigs with mild and moderate inflamation (actually red stomach color) eating the non-GM feed than GM feed.
- The uterusus of conventionally fed pigs accounted for 0.10% of body weight; for GM-fed pigs, it was 0.12% of body weight.
- The differences in uterus weights disappear if more conventional statistical analysis is used.
- Again, the dose makes the poison; yet, the heaviest uterus in the GM-fed group weighed less than the heaviest uterus in the non-GM-fed group.
- Even if the differences were real, other causes that were not excluded were zearalenones in the corn, isoflavones in the soybean, or the onset of puberty!
- The crop varieties used was not determined, and nutritional analysis of the feed was never conducted to ensure pigs were fed equivalent diets.
Additional expert assessments:
- Response to a feeding study in pigs by Carman et al, by FSANZ (Food Standards Australia New Zealand)
- Detailed comment on Carman et al (2013): study design and conduct, by FSANZ
- Australian Office of the Gene Technology Regulator (OGTR)
- Lack of care when choosing grains invalidates pig feeding study
- Pigs in the real world — feed them different diets, measure many health parameters, some will show differences – but what does it all mean?
- Full statement by Professor Robert Friendship, University of Guelph
- UK Science Media Centre – GM feeding study in pigs – experts respond
- Mark Lynas – GMOs pig study – more junk science
- You Can Put Lipstick On A Pig (Study), But It Still Stinks, by Henry Miller and Bruce Chassy