Full Statement by Professor Robert Friendship, University of Guelph on Study by Carman et al on Feeding of Genetically Modified Corn and Soybeans to Pigs

Dr Robert Friendship, a professor in the Department of Population Medicine at the Ontario Veterinary College, University of Guelph and a swine health management specialist, reviewed the paper [see reference below]. He concluded that “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.”

Regarding the other finding that the researchers held out as proof that the GMO fed pigs were different was that the uterus weight was different between the two groups. Dr Friendship noted that the authors did not appear unbiased in their discussion. “The research had a number of factors that could not be controlled for. It is disappointing that the authors of the paper did not admit the weaknesses of the study design and caution readers that there may be many reasons for a difference in uterine weight. Unfortunately instead of presenting a fair discussion they made wild speculation about the weight difference such as the heavier weight might indicate cancer. A flaw in the design of the study is that treatment is applied at the pen level and all the statistical analysis is done at the individual animal level. They did not suggest that the heavier uterine weight might be a result of some of the pigs in one pen of 42 pigs reaching puberty, which would be a reasonable possibility or that there may be estrogen-like substances in the feed at low levels. The testing that was performed for mycotoxins which are capable of producing estrogen-like compounds and are common was completely inadequate to rule-out this possibility. Overall the study is flawed but if you ignore the misinterpretation of the stomach colour, the research shows there is no difference in the two groups of pigs.”
“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

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