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GMOs - health concerns

GMOs - Health Concerns | Garden Organic
GM is a contentious issue. This article looks particularly at how it is used in crops, and the potential health risks.
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Are there health risks behind genetic modification? 🔗

The issues are complex. But GM is unlikely to go away. As organic growers and suppliers – the more we understand the subject, the greater strength we have in order to influence safety regulations, to prevent contamination, and to encourage governments to support growers and farmers to use other less invasive crop cultivation.

What is Genetic Modification?

A Genetically Modified Organism is simply something whose genetic material (DNA) has been interfered with in a way that does not occur naturally by mating and/or natural breeding.

In the past, scientists ‘introduced’ or transferred the DNA from one species to another. Now they use so-called ‘editing’ techniques to change the host DNA. This is called genetic engineering, as opposed to 'modification'. It enables scientists to change desired traits or features in an organism. This can enhance a crop’s resistance to disease, for instance, or make it resilient to weedkiller/herbicide.

Why are there concerns about the health and safety of GM crops?

It is often claimed that there is no evidence of dangers to health from GM crops and foods. They have been in the food chain for over 20 years. However, the regulatory process to ensure their safety is almost entirely based on industry studies - the very industries that produce the GM crops.

“ One thing that surprised us is that US regulators rely almost exclusively on information provided by the biotech crop developer, and those data are not published in journals or subjected to peer review…”wrote Prof David Schubert in his report Safety testing and regulation of genetically engineered food, 2006.

“Monsanto should not have to vouchsafe the safety of biotech food. Our interest is in selling as much of it as possible. Assuring its safety is the FDA’s job” said Philip Angell, Monsanto’s director of corporate communications. Indeed, up until 2009, scientists in America were denied access to GM seeds to test if the crops were safe to eat or harmed the environment.

Recent research (published in Nature, November 2016) shows that genetic engineering creates clear compositional differences within maize crops. There is a marked increase in putrescine and especially cadaverine- these substances are potentially toxic, as they enhance the effects of histamine, thus heightening allergic reactions.

A new potato has been genetically engineered not to show bruising. However it still bruises - its just that the bruises don't show, because the melanin gene has been suppressed. A unwelcome side effect of this engineering has caused an increase in the potato's aminoadipic acid content. This acid has been show to increase the risk of diabetes. Equally worrying is the fact that when a potato is bruised or damaged (and remember this engineering doesn't stop the bruising, it just doesn't show the discolouration) it releases toxins. Therefore consumers are potentially eating toxins unwittingly. See this report from one of the scientists involved in producing this genetically engineered potato.

Studies on humans and their consumption of GM foods are few. However there are numerous adverse effects on laboratory animals (see below) which include hepatic, pancreatic, renal and reproductive impacts. Concerned scientists argue that these health risks could well be present for humans.

Also there is the strong risk of ingesting traces of the herbicides associated with GM crops. Exposure to 2,4-D, for instance, has been linked to Non-Hodgkin's lymphoma; Dicamba is suspected of causing birth defects; and glyphosate formulations are potentially carcinogenic. See WHO report.

It is disingenuous, therefore, for proponents of GM to claim that there is no danger to human health.

Americans have been eating GM food for over 20 years, over 80% of their processed food contains GMOs. In that time, official government statistics show that chronic illnesses have increased steeply in the US. And, without muddling causation and correlation, a link with GM and associated toxic chemicals has yet to be ruled out.

GM corn combats liver cancer?

Recent announcements claim that scientists have genetically engineered sweetcorn so that it no longer contains a carcinogenic chemical. Called aflatoxin, this chemical can cause liver cancer. Heralded as a 'breakthrough", the producers of this corn are ignoring the fact that in 2010, conventional breeding already produced corn that resists aflatoxin contamination. This corn is already grown safely across the world. So why is there need to invest billions in producing a new genetically engineered product? See GMOs - Political and Ethical Concerns. Read the full story here.

GM animal feed

Although GMO crops are not grown in the UK, most animal feed used by farmers is made from imported GM crops such as soy from Argentina.

To test the safety of genetically modified animal feeds, regulatory authorities in the US and Europe require only a maximum of 90 days’ feeding time of GM crops to animals. This does not allow for a full understanding of the long term effects.

Independent peer-reviewed studies have found many health issues in farm animals which have been fed GMOs. Stomach inflammation and diarrhoea in piglet and hens is common. (See full list below.) Other problems occur in liver and kidneys, altered gut bacteria and intestinal abnormalities, excessive growth in the lining of the gut - similar to a pre-cancerous condition, immune disturbances and allergic reactions, and a heavier uterus. A new study (from 2017-20) has been set up in Aarhus University, Denmark to investigate the effects of glyphosate (from GM feed) on piglets' gut.

Mice fed for 5 generations on GM triticale (a wheat/rye hybrid) showed enlarged lymph nodes: the colostrum and milk of goats fed a GM soya diet contained a significantly lower percentage of protein and fat compared to the non GM diet. For a full list of research papers, see references below.

These problems may arise from the GM crop itself or from residues of the pesticides used on them. See GMO Environmental concerns .


Here is a list of over 40 health studies on GM food in animals. For a fuller understanding of the health risks, and the inadequacies of regulatory testing, we recommend you also read GMO Myths and Truths (2015) Robinson, Antoniou, Fagan.

  1. Séralini GE, Mesnage R, Clair E, Gress S, de Vendômois JS, Cellier D. Genetically modified crops safety assessments: Present limits and possible improvements. Environ Sci Eur. 2011;23. doi:10.1186/2190-4715-23-10.
  2. Séralini GE, Cellier D, Spiroux de Vendomois J. New analysis of a rat feeding study with a genetically modified maize reveals signs of hepatorenal toxicity. Arch Environ Contam Toxicol. 2007;52:596–602.
  3. De Vendomois JS, Roullier F, Cellier D, Séralini GE. A comparison of the effects of three GM corn varieties on mammalian health. Int J Biol Sci. 2009;5:706–26.
  4. Trabalza-Marinucci M, Brandi G, Rondini C, et al. A three-year longitudinal study on the effects of a diet containing genetically modified Bt176 maize on the health status and performance of sheep. Livest Sci. 2008;113:178–190. doi:10.1016/j.livsci.2007.03.009.
  5. Kilic A, Akay MT. A three generation study with genetically modified Bt corn in rats: Biochemical and histopathological investigation. Food Chem Toxicol. 2008;46:1164–70. doi:10.1016/j.fct.2007.11.016.
  6. US Food and Drug Administration (FDA). Biotechnology consultation note to the file BNF No 00077. Office of Food Additive Safety, Center for Food Safety and Applied Nutrition; 2002. Available at: http://bit.ly/ZUmiAF.
  7. Malatesta M, Biggiogera M, Manuali E, Rocchi MBL, Baldelli B, Gazzanelli G. Fine structural analyses of pancreatic acinar cell nuclei from mice fed on genetically modified soybean. Eur J Histochem. 2003;47:385–388.
  8. Malatesta M, Caporaloni C, Gavaudan S, et al. Ultrastructural morphometrical and immunocytochemical analyses of hepatocyte nuclei from mice fed on genetically modified soybean. Cell Struct Funct. 2002;27:173–80.
  9. Vecchio L, Cisterna B, Malatesta M, Martin TE, Biggiogera M. Ultrastructural analysis of testes from mice fed on genetically modified soybean. Eur J Histochem. 2004;48:448-54.
  10. Malatesta M, Boraldi F, Annovi G, et al. A long-term study on female mice fed on a genetically modified soybean: effects on liver ageing. Histochem Cell Biol. 2008;130:967–977.
  11. Schrøder M, Poulsen M, Wilcks A, et al. A 90-day safety study of genetically modified rice expressing Cry1Ab protein (Bacillus thuringiensis toxin) in Wistar rats. Food Chem Toxicol. 2007;45:339-49. doi:10.1016/j.fct.2006.09.001
  12. Brasil FB, Soares LL, Faria TS, Boaventura GT, Sampaio FJ, Ramos CF. The impact of dietary organic and transgenic soy on the reproductive system of female adult rat. Anat Rec Hoboken. 2009;292:587–94. doi:10.1002/ar.20878.
  13. Carman JA, Vlieger HR, Ver Steeg LJ, et al. A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet. J Org Syst. 2013;8:38–54.
  14. Freese W, Schubert D. Safety testing and regulation of genetically engineered foods. Biotechnol Genet Eng Rev. 2004:299-324.
  15. Pusztai A, Bardocz S. GMO in animal nutrition: Potential benefits and risks. In: Mosenthin R, Zentek J, Zebrowska T, eds. Biology of Nutrition in Growing Animals.Vol 4. Elsevier Limited; 2006:513–540. Available at: http://www. sciencedirect.com/science/article/pii/S1877182309701043.
  16. Netherwood T, Martin-Orue SM, O’Donnell AG, et al. Assessing the survival of transgenic plant DNA in the human gastrointestinal tract. Nat Biotechnol. 2004;22:204–209. doi:10.1038/nbt934.
  17. Heritage J. The fate of transgenes in the human gut. Nat Biotechnol. 2004;22:170-2. doi:10.1038/nbt0204-170.
  18. Yum HY, Lee SY, Lee KE, Sohn MH, Kim KE. Genetically modified and wild soybeans: an immunologic comparison. Allergy Asthma Proc. 2005;26:210-6.
  19. Nordlee JA, Taylor SL, Townsend JA, Thomas LA, Bush RK. Identification of a Brazil-nut allergen in transgenic soybeans. N Engl J Med. 1996;334:688-92. doi:10.1056/NEJM199603143341103.
  20. Aris A, Leblanc S. Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada. Reprod Toxicol. 2011;31.
  21. Goldstein DA, Dubelman S, Grothaus D, G. Hammond BG. Comment: Aris and Leblanc “Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada.” Reprod Toxicol. 2012;33:120-121.
  22. Aris A. Response to comments from Monsanto scientists on our study showing detection of glyphosate and Cry1Ab in blood of women with and without pregnancy. Reprod Toxicol. 2012;33:122-123
  23. Séralini GE, Mesnage R, Clair E, Gress S, de Vendômois JS, Cellier D. Genetically modified crops safety assessments: Present limits and possible improvements. Environ Sci Eur. 2011;23. doi:10.1186/2190-4715-23-10.
  24. Séralini GE, Cellier D, Spiroux de Vendomois J. New analysis of a rat feeding study with a genetically modified maize reveals signs of hepatorenal toxicity. Arch Environ Contam Toxicol. 2007;52:596–602.
  25. De Vendomois JS, Roullier F, Cellier D, Séralini GE. A comparison of the effects of three GM corn varieties on mammalian health. Int J Biol Sci. 2009;5:706–26.
  26. Trabalza-Marinucci M, Brandi G, Rondini C, et al. A three-year longitudinal study on the effects of a diet containing genetically modified Bt176 maize on the health status and performance of sheep. Livest Sci. 2008;113:178–190. doi:10.1016/j.livsci.2007.03.009.
  27. Kilic A, Akay MT. A three generation study with genetically modified Bt corn in rats: Biochemical and histopathological investigation. Food Chem Toxicol. 2008;46:1164–70. doi:10.1016/j.fct.2007.11.016.
  28. US Food and Drug Administration (FDA). Biotechnology consultation note to the file BNF No 00077. Office of Food Additive Safety, Center for Food Safety and Applied Nutrition; 2002. Available at: http://bit.ly/ZUmiAF.
  29. Malatesta M, Biggiogera M, Manuali E, Rocchi MBL, Baldelli B, Gazzanelli G. Fine structural analyses of pancreatic acinar cell nuclei from mice fed on genetically modified soybean. Eur J Histochem. 2003;47:385–388.
  30. Malatesta M, Caporaloni C, Gavaudan S, et al. Ultrastructural morphometrical and immunocytochemical analyses of hepatocyte nuclei from mice fed on genetically modified soybean. Cell Struct Funct. 2002;27:173–80.
  31. Vecchio L, Cisterna B, Malatesta M, Martin TE, Biggiogera M. Ultrastructural analysis of testes from mice fed on genetically modified soybean. Eur J Histochem. 2004;48:448-54.
  32. Malatesta M, Boraldi F, Annovi G, et al. A long-term study on female mice fed on a genetically modified soybean: effects on liver ageing. Histochem Cell Biol. 2008;130:967–977.
  33. Schrøder M, Poulsen M, Wilcks A, et al. A 90-day safety study of genetically modified rice expressing Cry1Ab protein (Bacillus thuringiensis toxin) in Wistar rats. Food Chem Toxicol. 2007;45:339-49. doi:10.1016/j.fct.2006.09.001
  34. Brasil FB, Soares LL, Faria TS, Boaventura GT, Sampaio FJ, Ramos CF. The impact of dietary organic and transgenic soy on the reproductive system of female adult rat. Anat Rec Hoboken. 2009;292:587–94. doi:10.1002/ar.20878.
  35. Carman JA, Vlieger HR, Ver Steeg LJ, et al. A long-term toxicology study on pigs fed a combined genetically modified (GM) soy and GM maize diet. J Org Syst. 2013;8:38–54.
  36. Freese W, Schubert D. Safety testing and regulation of genetically engineered foods. Biotechnol Genet Eng Rev. 2004:299-324.
  37. Pusztai A, Bardocz S. GMO in animal nutrition: Potential benefits and risks. In: Mosenthin R, Zentek J, Zebrowska T, eds. Biology of Nutrition in Growing Animals.Vol 4. Elsevier Limited; 2006:513–540. Available at: http://www. sciencedirect.com/science/article/pii/S1877182309701043.
  38. Netherwood T, Martin-Orue SM, O’Donnell AG, et al. Assessing the survival of transgenic plant DNA in the human gastrointestinal tract. Nat Biotechnol. 2004;22:204–209. doi:10.1038/nbt934.
  39. Heritage J. The fate of transgenes in the human gut. Nat Biotechnol. 2004;22:170-2. doi:10.1038/nbt0204-170.
  40. Yum HY, Lee SY, Lee KE, Sohn MH, Kim KE. Genetically modified and wild soybeans: an immunologic comparison. Allergy Asthma Proc. 2005;26:210-6.
  41. Nordlee JA, Taylor SL, Townsend JA, Thomas LA, Bush RK. Identification of a Brazil-nut allergen in transgenic soybeans. N Engl J Med. 1996;334:688-92. doi:10.1056/NEJM199603143341103.
  42. Aris A, Leblanc S. Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada. Reprod Toxicol. 2011;31.
  43. Goldstein DA, Dubelman S, Grothaus D, G. Hammond BG. Comment: Aris and Leblanc “Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada.” Reprod Toxicol. 2012;33:120-121.
  44. Aris A. Response to comments from Monsanto scientists on our study showing detection of glyphosate and Cry1Ab in blood of women with and without pregnancy. Reprod Toxicol. 2012;33:122-123