The old saying, “ignorance is bliss”, may not apply to genetically modified organisms (GMOs), but the public debate on the pros and cons of GMOs may not enlighten you either. The debate is full of rhetoric, opinion and falsehood as well as fact – distinguishing fact from opinion, pseudoscience and falsehood is difficult because the ‘facts’ are often provided by scientific studies funded by the very entities that stand to profit or benefit from the GMOs or other enabling technologies (like herbicides). This conflict of interest does not necessarily mean that the research is invalid, but such research often treats GMOs more favourably than research conducted by organisations with no conflict of interest (Diels et al, 2011). Another serious flaw in all research related to GMOs is the nature of the scientific method – to isolate one or more variables in a reductionist fashion in order to study their effects is to deny the very nature of complex systems, including the human body and especially genetics. For example, glyphosate has been studied in its isolated form as well as in the formulated Roundup™, where glyphosate is the main active ingredient. The toxicity of glyphosate is considerably lower than the toxicity of Roundup™ (Clair et al, 2012; Mesnage et al, 2012; Mesnage et al, 2014), and both are even more toxic when combined with Bacillus thuringiensis (Bt) toxin (Mesnage et al, 2013). Complicated, isn’t it? Research is easily manipulated to deliver the required results, and many articles aimed at the general public carefully cherry-pick the reported research to deliver the desired message. These proclivities complicate the debate and make research and reporting very difficult.

The Cartagena Protocol on Biosafety defines a GMO as a “living modified organism”, or “…any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology” (Secretariat of the Convention on Biological Diversity, 2000, p. 4). The term ‘modern biotechnology’ does not refer to methods used in traditional selective breeding; it refers to the application of gene manipulation technologies, such as the insertion, deletion and modification of genes from different species, usually using horizontal gene transfer. Horizontal gene transfer simply means the non-reproductive transfer of genetic information. One common method of transferring genes in this manner is through inserting the gene into a virus or bacteria which then transfers the gene into the target cell. Many different types of organisms have been genetically modified, including bacteria, plants, insects, fish and mammals. The rest of this article will focus on genetically modified (GM) plants, specifically crop plants. GM crops that have been approved for commercial release (in the US) include corn, soybeans, zucchini, crookneck squash, rice, papaya, sugar beet, potato, tomato, cotton, Lucerne, canola and peas. Many more are currently under trial. Australia produces GM cotton and canola commercially.

The genetic modification of an organism does not occur in a vacuum – there is always a proximate motive and an ultimate motive for applying this technology to a species. For example, the genetic modification of crops has been touted as a technology that can increase cropping productivity through crop protection (operational yield) to the point where we could “feed the world”, similar to the argument put forward for the disastrous Green Revolution in the middle of last century. ‘Increasing productivity through crop protection’ is the proximate motive for applying genetic engineering in this case. The technology is not cheap, however, and the ultimate motive for applying this technology – especially over free alternatives – is that the technology makes a profit for the corporation that produces it. Let’s not forget that in some countries, corporations are obligated by law to maximise their profits for the shareholders; therefore it would hardly be a surprise that profit was the ultimate motive for many decisions related to genetic engineering. Again, profit as an ultimate motive does not make the technology ‘bad’ or ‘wrong’ – however, it calls into question the veracity of the corporation promoting it as a solution.

We’ve seen that crop protection – through resistance to pests and diseases – is a proximate motive for the genetic modification of crops. Crop protection also includes plants modified to be resistant to herbicides – the surrounding weed burden can be sprayed and the crop will survive. Other proximate motives that have been identified to date are increased intrinsic yield (the theoretical maximum yield), improved nutritional content, improved taste, improved storage capability, decreased insecticide and herbicide use, and increased oil production (e.g. maize for biofuels) or oil profile (more Omega 3, less Omega 6). These are the promises, but do GMOs actually deliver on their promises?

Research indicates that overall they do not. The Union of Concerned Scientists published a report in 2009 entitled Failure to Yield which evaluated the overall yield of genetically modified (GM) crops given 20 years of research (Gurian-Sherman, 2009). Their conclusion was that genetic modification has not delivered the promised increases to intrinsic yield but has contributed to a slight increase in operational yield (reduction in yield losses) for Bt corn only (with its concomitant decrease in insecticide use). However, even this slight improvement diminishes over time as the target insects evolve resistance to Bt toxin (Campagne et al, 2013). Insect resistance to the Bt toxin, along with weed resistance to glyphosate, are the two major reasons that the use of GM crops does not lead to decreased insecticide and herbicide use. In the U.S. alone, glyphosate-resistance in weeds has led to a 239 million kilogram increase in herbicide use from 1996 to 2011 (Benbrook, 2012). The DOW chemical company plans to introduce GM corn and soybeans that are resistant to the powerful herbicide 2,4-D, the less toxic constituent of Agent Orange, as well as a newer herbicide called quizalofop (Cummins, 2012). Based on the results for glyphosate, that action is likely to increase herbicide use further for similar reasons. See the exceptional report by Seidler (2014) for a fuller treatment on current pesticide use and genetically modified crops. GM crops based on improved taste or storage capability have either never reached the market or have not remained on the market for long (e.g. Flavr Savr tomato).  Nutritionally, significant differences have been found between Bt corn and non-GM corn which is interesting because GM crops are often approved for use based on being substantially equivalent to non-GM crops in terms of macronutrients, micronutrients, toxins and allergens (Abdo et al, 2013). The differences could not be considered an improvement, rather a cause for concern. The Canadian Biotechnology Action Network (2014) has produced an excellent report, Will GM Crops Feed the World?, which sums up the actual problems with hunger; biotechnology will only exacerbate these problems, not solve them.

We’ve seen that overall, GMOs do not deliver on their promised benefits. Another question to ask is whether the technology (or associated technology) is harmful to living organisms. Harmful effects must be considered over the lifespan of the individual, as well as across generations. In other words, do we know enough about GM crops to declare them safe for all eternity? After all, most GM crops are targeted for human or livestock consumption, directly or indirectly via processed foods. Research indicates that we cannot make a claim of safety, and as we’ll see later, we cannot control the process and results of genetic modification. Although not related to a GM crop, the earliest example of a significant health risk from GMOs occurred in 1989, prior to the commercial introduction of GM crops. The organism at fault was a Bacillus bacteria, genetically engineered to mass produce the food supplement L-Tryptophan (an amino acid). As a by-product of its metabolic fermentation, the Bacillus also produced a substance that turned out to be toxic. The toxin was not filtered out of the product properly and went on to cause a condition called Eosinophilia–Myalgia Syndrome (EMS) which killed dozens of people and injured thousands. An important point is that no quality assurance or safety process detected this toxic substance, nor was it understood that such a by-product was possible.

GM crops have been commercially produced since the mid-1990s. By now there should be unequivocal longitudinal and cross-generational research indicating their safety. There is no such research. A multi-year study is about to begin in Russia that will test the effects on rats of eating GM maize and the herbicides that support it (Vidal, 2014) – this will be a longitudinal study, but not a cross-generational study. Shorter studies abound in the literature.

De Vendômois et al (2009) studied rats fed Roundup-tolerant maize or Bt maize for 5 weeks and 14 weeks. The study revealed adverse health effects, mainly hepatorenal (liver and kidney) toxicity, related to the amount of GM food consumed as well as the sex of the animal. Gab-Alla et al (2012) also studied rats fed GM corn for different periods, finding adverse changes in serum biochemistry and organ weight. Seralini et al (2014) found similar hepatorenal problems in rats and underscored the need for longitudinal studies. Zdziarski et al (2014) published a literature review on research relating to the relationship between GM crops and health in lab rats. Of the 47 GM crops approved for human or animal consumption, only 9 crops were mentioned in the literature. Most studies had methodological problems or issues with internal or external consistency. The authors concluded that no conclusions could be reached about the safety of GM crops. They simply have not been shown to be safe to consume by any type of living organism.

A complicating factor in the study of GM crop safety is the large herbicide burden for these crops, already discussed previously. However, the herbicide burden must be taken into account in determining safety and cannot be ignored as irrelevant. Two important studies by Samsel & Seneff (2013a; 2013b) suggest that glyphosate acts to suppress cytochrome P450 enzymes which are responsible for detoxifying environmental pollutants in the body. Thus the impact on the human body and its many systems of homeostasis may be felt over the long term and not evidenced over the short term. This impact may include celiac disease, gluten intolerance, gut dysbiosis, Alzheimer’s disease, obesity, heart disease, depression, diabetes, cancer and infertility. Indeed, the American Academy of Environmental Medicine (AAEM) has taken the bold step of publishing a warning to doctors to alert their patients to the dangers of GMOs in the food supply and avoid them if possible (American Academy of Environmental Medicine, 2012). The AAEM points out that animal studies have indicated GM crop risks could include problems with infertility, the immune system, accelerated aging, insulin regulation, and damage to major organs and the gastrointestinal system. Swanson et al (2014) underline a remarkable series of correlations between the presence of GM crops in our food supply (in particular, glyphosate-resistant crops) and the huge increases in incidence of chronic illnesses in the United States.

The toxin burden in Bt GM crops should not be overlooked. It is worth remembering that a genetically modified Bt crop produces the toxin in every cell of the plant. It cannot be washed off. Aris & Leblanc (2011) reported that Bt toxin – which clearly survives digestion – was detected in the blood of 93% of pregnant women tested in their study. Sadly, it was also detected in 80% of their unborn children.

Next week in Part 2, I will delve into mechanisms that might explain the deleterious health effects of GM crops, the ability of such crops and their transgenes to be contained, the protection of the public by regulatory agencies and safer alternatives to GM crops.


References for Part 1:

ABDO, E M, BARBARY, O M AND SHALTOUT, O E 2013. Chemical Analysis of BT corn “Mon-810: Ajeeb-YG®” and its counterpart non-Bt corn “Ajeeb”. IOSR Journal of Applied Chemistry, 4(1), 55-60.

AMERICAN ACADEMY OF ENVIRONMENTAL MEDICINE 2012. Doctors’ Health Warning: Avoid Genetically Modified Foods. Available:

ARIS, A & LEBLANC, S 2011. Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, CanadaReprod Toxicol, 31(4), 528-533.

BENBROOK, C 2012. Impacts of genetically engineered crops on pesticide use in the U.S. — the first sixteen years. Environmental Sciences Europe, 24(1), 1-13.

CAMPAGNE, P, KRUGER, M, PASQUET, R, LE RU, B & VAN DEN BERG, J 2013. Dominant Inheritance of Field-Evolved Resistance to Bt Corn in Busseola fusca. PLoS ONE, 8(7). Available:

CANADIAN BIOTECHNOLOGY ACTION NETWORK 2014. Will GM Crops Feed the World? Ottawa: Canadian Biotechnology Action Network (CBAN).

CUMMINS, J 2012. New GM Crops Tolerant To Old Toxic Herbicides a Step Backwards. ISIS. Available:

DE VENDÔMOIS, J S, ROULLIER, F, CELLIER, D & SÉRALINI, G E 2009. A Comparison of the Effects of Three GM Corn Varieties on Mammalian Health. Int J Biol Sci 5(7), 706-726.

DIELS, J, CUNHA, M, MANAIA, C, SABUGOSA-MADEIRA, B & SILVA, M 2011. Association of financial or professional conflict of interest to research outcomes on health risks or nutritional assessment studies of genetically modified products. Food Policy, 36(2), 197-203.

GAB-ALLA, A A, EL-SHAMEI, Z S, SHATTA, A A, MOUSSA, E A & RAYAN, A M 2012. Morphological and Biochemical Changes in Male Rats Fed on Genetically Modified Corn (Ajeeb YG). J Am Sci, 8(9), 1117- 1123.

GURIAN-SHERMAN, D 2009. Failure to yield: Evaluating the performance of genetically engineered crops. Union of Concerned Scientists. Available:

MESNAGE, R, BERNAY, B & SÉRALINI, G-E 2012. Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. Toxicology. Available:

MESNAGE, R, CLAIR, E, GRESS, S, THEN, C, SZÉKÁCS, A & SÉRALINI, G-E 2013. Cytotoxicity on human cells of Cry1Ab and Cry1Ac Bt insecticidal toxins alone or with a glyphosate-based herbicide. Journal of Applied Toxicology, 33(7), 695-699.

MESNAGE, R, DEFARGE, N, SPIROUX DE VENDÔMOIS, J & SÉRALINI, G-E 2014. Major Pesticides Are More Toxic to Human Cells Than Their Declared Active Principles. BioMed Research International, 2014.

SAMSEL, A & SENEFF, S 2013a. Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intolerance. Interdisciplinary toxicology, 6(4), 159-184.

SAMSEL, A & SENEFF, S 2013b. Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases. Entropy, 15(4), 1416-1463.

SECRETARIAT OF THE CONVENTION ON BIOLOGICAL DIVERSITY 2000. Cartagena Protocol on Biosafety to the Convention on Biological Diversity: text and annexes. Montreal: Secretariat of the Convention on Biological Diversity.

SEIDLER, R J 2014. Pesticide Use on Genetically Engineered Crops. Environmental Working Group. Available:

SERALINI, G-E, CLAIR, E, MESNAGE, R, GRESS, S, DEFARGE, N, MALATESTA, M, HENNEQUIN, D & DE VENDOMOIS, J 2014. Republished study: long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize. Environmental Sciences Europe, 26(1), 14.

SWANSON, N L, LEU, A, ABRAHAMSON, J & WALLET, B 2014. Genetically engineered crops, glyphosate and the deterioration of health in the United States of America. Journal of Organic Systems, 9(2). Available:

VIDAL, J 2014. Largest international study into safety of GM food launched by Russian NGO. The Guardian, 12/11/2014. Available:

ZDZIARSKI, I M, EDWARDS, J W, CARMAN, J A & HAYNES, J I 2014. GM crops and the rat digestive tract: A critical review. Environment International, 73, 423-433.

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