Question
Answer
Expert response from Andrew Bartholomaeus
B.Pharm, PhD, Cert Ag (III)
Friday, 10/23/2015 14:09
The genes and therefore the physiology and biochemistry of a rat, and other experimental animals, are actually very similar to humans. Humans even have a gene for a tail but it is switched off in humans. This does not mean however that effects seen in rats are automatically relevant for humans. Very often a careful consideration of the physiology of the rat and that of humans is necessary to determine which effects seen in rats are relevant to humans. Equally, in order for a rat study to be scientifically credible it needs to be carefully designed, conducted and interpreted. Failure to pay attention to these details is a major flaw in those few studies that have claimed to find adverse effects in animals fed GMOs.
Studies of whole foods in rats, as opposed to specific proteins or other constituents, are not relevant to humans because the design does not support robust interpretation. The general safety of GMOs to humans is better assessed from compositional analysis of the modified plants and from the knowledge of the wide variation that exists in the genes and composition of all plants including food crops. A good, not too technical, paper that discusses the relevance of animals studies on GMOs is that of Bartholomaeus et al (2013) "The use of whole food animal studies in the safety assessment of genetically modified crops", Critical Reviews in Toxicology, 43 (S2) 1-24. Another pertinent paper is that by van Eenennaam & Young 2014 "Prevalence and impacts of genetically engineered feedstuffs on livestock populations”, American Society of Animal Health 92, 4255-4278. This paper looks at the use of GM foods in livestock production in the USA. Every year over 9 billion animals are produced for human consumption in the USA and 95 percent are fed GM diets.
Two of the most sensitive toxicological endpoints are effects on weight gain and reproductive performance which are also two of the critical economic considerations for farmers and therefore are carefully watched by them. Also, when animals are slaughtered for consumption they are routinely examined for any obvious signs of disease. Despite the very wide spread use of GM feed in such enormous numbers of animals there is no evidence of any adverse effects from the introduction of GM feed around 20 years ago. No animal toxicity study in a laboratory could ever compete with an ongoing "study" of such magnitude.
