Environmental & Health Impact of GM Crops


Hi friends,

My first post is a paper I wrote for a graduate-level class on Argumentative Research and Writing. Please be sure to share your thoughts on my paper. I will surely appreciate your feedback.


The apparent benefits of GM crops include higher yields, lower labor cost, soil preservation, reduction of herbicide input, decline in CO2 emissions, and affordable prices to buyers, which resulted in a rapid takeover of the corn, soybeans, and cottonseed markets. However, a critical review of these perceived advantages reveals troublesome trends such as modest or negligible gains in realized crop yields, genetic pollution of traditional varieties, rapid development of glyphosate resistance in weeds and Bt-toxin in root worms, environmental damage due to alterations to the ecological balance of non-target species, alarming toxicological effects in rats and pigs, and detectable levels of Bt-toxins in human blood samples. Current GM-based agricultural models must be revised to prevent irreversible health and environmental damage.


Did you know that 170 million hectares were planted with biotech seeds in 2012 around the globe? Genetically modified (GM) corn was first introduced in the US in 1996 as “Roundup Ready Corn” and this technology was adopted at unprecedented speed (Clive 2012). Genes store all the functional and reproductive information in all living beings. When the cell’s genetic material is manipulated using novel Genetic Engineering techniques, new and desirable traits from unrelated organisms are added to target species. In the present case, new corn, soybeans, and cottonseeds varieties where designed to have the ability to tolerate the application of glyphosate-based herbicides using bacterial gene fragments (Dill 2005, 219).

GM biotechnology is the result of advances in Plant Genetics and Molecular Biology, and scientists in the field are proud to have acquired the capability of introducing genes from microorganisms into plants, thus giving them traits that cannot be easily achieved by common propagation methods such as seed selection, hybridization, and the use of cultivar techniques (Dill 2005, 219). Multiple varieties with other desirable properties have been produced over the years, but glyphosate-resistant plants were the first commercially available GM crops, and remain the most popular to this day.

Another group of GM crops was created to actively fight against pests. Bacillus thuringiensis (Bt) is a soil bacteria that has been used as natural pest control for decades because it produces a toxin that has insecticidal and nematicidal properties. It belongs to the same family as Bacillus anthracis, which is the bacteria that produces anthrax spores. More specifically, Bt produces spores that contain crystalline proteins, also called Cry proteins, that become activated in the digestive tract of insects. Once the Bt toxin has been activated, it pokes holes in the intestinal walls of its victim and paralyzes the digestion process, thus forcing the organism to stop eating. While the poisoned target starves to death, it may occur that opportunistic live Bt bacteria colonize the agonizing bug and feed on it (Petzold-Maxwell et al. 2013, 622). This knowledge was employed by genetic engineers to isolate the Cry genes that produce Cry proteins and insert them in corn plants. As a result, we now have toxin-producing maize that is designed to poison corn rootworms, as well as other insects and nematodes, with the goal of protecting corn plants against pest damage, thus increasing crop yields (Lundgren and Duan 2013, 657).

The advantages of using GM crops for farmers are immediate and include higher initial yields, easy weed control, and no-till planting, which saves time, money, and reduces soil erosion (Fernandez-Conejo et al. 2012). But, do we have sufficient knowledge of plant genetics to analyze all the variables involved? Have we compiled sufficient data to predict how the extensive use of GM crops will impact the environment and our health? Few governments have implemented measures to systematically monitor the adverse effects that GM crops could have on the environment, a worrisome fact when confronted with the possibility of permanent and substantial alterations to the environment and staple food crops. Currently, the working assumption on GM crops is that their production is sustainable, nutritionally equivalent to traditional harvest, and safe to eat for humans and animals; however, new research studies suggest that these views should be revised based on the alarming results of recent toxicological studies and numerous signs of environmental distress.

What “They Say” about GM Crop Production

It has been estimated that around 11% of all arable land on earth is planted with GM crops, and 89% of it derives from production in the US, Canada, Brazil, Argentina, and India (Clive 2012). Globally, the annual value of biotech seeds sold amounts to at least US$15 billion (Clive 2012), so nobody should be surprised to find that multinational corporations fiercely defend their markets and aggressively try to increase their sales. Similarly, scientists who work in the field, and receive research grants from interest groups, must prove the value of their discoveries and stand strong against criticism.

Opponents of the use of GM modified crops argue that there are many essential facts about gene regulation and expression that we still do not understand and that the foreign genes could have unintended effects, such as the production of secondary toxins, allergens, altered levels of proteins, and other nutrients, all of which could disrupt the food chain at various levels (IRT 2013). Natural News is a popular natural health advocacy organization with a large web portal, and they have partnered with multiple like-minded groups to spread the idea that there has been a increase in the incidence of allergies, food intolerances, autoimmune disorders, and cancer in humans since the introduction of GM crops (Landsman 2013).

In essence, the issue of environmental and health safety of GM crops is a global challenge with major economic repercussions, and it is puzzling to see that it does not receive the level of attention it deserves. This apparent indifference, linked to weak regulatory oversight, creates a climate where business-driven interests prevail and consequences wait to be uncovered, although we currently receive warnings from diverse fronts.

Plant and Insect Resistance
Millions of farmers have switched to biotech crops because they “deliver substantial, and sustainable, socio-economic and environmental benefits” (Clive 2012). The contributions of GM crops to mankind in the period from 1996 to 2011 can be summarized as follows (Clive 2012):
1.Cumulative gains due to increments in crop yields amounts to US$98.2 billion.
2.Pesticide savings are estimated at 473 million kg of pesticides (8.9%).
3.Reduction of carbon dioxide emissions in 2011 were 23.1 billion kg.
4.Conservation of biodiversity and reduction of deforestation by saving 108.7 million hectares of land from being used for farming.
5.Reduction of soil degradation from erosion and preservation of surface moisture.
6.Improved economic prospect to 15.0 million small farmers who got out of poverty.
7.Reduction of food prices due to increments in productivity and reduction of labor requirements.

To the contrary, other sources consider the less remarkable aspect of GM production, such as the accelerated appearance of glyphosate-resistant weeds. Some reports indicate that twenty four different species of weeds have been found to survive standard applications of Roundup in the US. The practice of rotating different herbicides was discontinued when GM seeds were introduced, and Roundup became the only herbicide used in GM fields (Gilbert 2013). It is unlikely that farmers will be able to control weeds with Roundup without tilling or ploughing in the near future, so the perceived soil and moisture preservation advantages of GM crops may be short-lived.

We must consider this development in the face of a study sponsored by the USDA and Monsanto. Results were collected from 1998 to 2003 on small plots, and the final conclusion states that using glyphosate at the standard rate of 0.8 kg/ha twice a year is effective controlling a variety of weeds, and applicable to corn production even in the absence of crop rotation. While variations in glyphosate sensitivity of the various types of weeds was observed, the development of glyphosate resistance was not noticed (Wilson et al. 2007, 900). Critics of Monsanto’s study debated that the plot size used in the study was so small that the probability of observing any resistance was marginal (Gilbert 2013).

As it turns out, concerns about the experimental design of Monsanto’s weed resistance study were well founded, because glyphosate resistance in weeds has been reported in 18 countries. The current standard application rate is now 1.5 kg glyphosate/ha, but it has been projected that it would increase to of 3.5 kg/ha by the year 2025 (Gilbert 2013). Therefore, the claims that growing GM crops helps the environment, lowers the amount of herbicides needed for effective weed control, and reduces pollution are marked for extinction.

Figure 1, “Glyphosate-resistant weed populations in the US and Canada, 2002-2012”

(Source: Map by Jeschke. n.d., https://www.pioneer.com/home/site/us/agronomy/weed-mgmt-and-glyphosate-resis/#fig2)

The sequence of maps illustrated in Figure 1 represent the proliferation of glyphosate-resistant weeds in the US and Canada. The spread of weeds tolerant to Roundup over a period of 10 years is evident over major regions of the North American geography. At the same time, the number of species of weeds that can survive after the application of glyphosate-based herbicides also increases. While this conservative report only includes eight confirmed cases of glyphosate-resistant weeds in North America, it is clear that weeds are evolving to survive chemical herbicides at a fast pace and current farming methods may not be applicable in the near future.

Toxicological Studies
In the US, the FDA has established that GM corn and soybean crops and their derivatives are not significantly different from traditional crops, and that they are safe for human and animal consumption. These conclusions are based on voluntary safety studies performed by the developers of GM seeds (FDA 2013). Biotech companies are not required to make public the results and methodology of their safety tests, and they often consider this information confidential.

A French study maintains, in spite of heavy criticism, that hormonal imbalances, liver failure, renal failure, cancer, and a shorter life expectancy was observed in rats fed Roundup-ready corn over a two-year period (Séralini et al. 2012, 4221). Critics point out that the methodology is invalid because the population group was not large enough (Butler 2012, 158), although it was the same size as Monsanto’s 90-day safety test study. But for some reason Monsanto’s results have not been questioned. In the end, the editor of Food Chemistry and Toxicology withdrew the publication of the article in question, while ignoring the author’s objections. This was probably done to avoid arbitrating a heated debate on the safety of GM crops, and because this is a sensitive issue for many, in view of the large economic impact of today’s biotech industry.

Nevertheless, a lesser known research paper on pig’s health was recently published, and so far it has escaped the publicity and heavy scrutiny sparked by the mice study mentioned above. A group of 168 piglets were selected, and half of them were fed a GM corn and soybeans diet, while the control group was fed a non-GM diet. Their autopsies were completed after 26 weeks, and a significantly higher incidence of severe stomach inflammation was reported in the GM-diet group of pigs. Moreover, a different level of stomach inflammation was observed on male pigs (22.2% v. 5.6% control) compared to female pigs (41.7% v. 18.9% control). This is probably due to the presence of Bt toxins (Cry 3Bb1 and Cry 1Ab proteins) in the digestive tract of pigs. Bt toxins generally form cationic channels in the intestinal walls once bound to suitable receptors. This is actually the same mechanism that kills the corn rootworms in the soil after ingesting Bt toxin. It is worth pointing out that the digestive system of pigs shares multiple similarities with humans, thus the need to perform additional experiments to supplement the data collected. Moreover, it is also suspected that a GM-based diet may result in reproductive problems in female pigs because the weight of their uterus was abnormally high. More research is needed to determine if higher uterine mass is a consequence of endometriosis, inflammation, polyps, or a different health problem (Carman et al. 2013, 38).

The increased use of GM crops goes hand-in-hand with widespread use of Monsanto’s glyphosate-based Roundup. Animals are frequently exposed to this herbicide because their feed is manufactured with GM grains highly contaminated with glyphosate. A Danish study reveals that cows ingest this GM feed, digest it, and absorb around 30% of the available glyphosate. Part of the absorbed glyphosate is excreted in the urine and the rest is metabolized in the liver and kidneys (Krüger et al. 2011, 187). Laboratory analysis on standard health markers such as creatinine, urea, cholesterol, liver enzymes, and kidney enzymes indicates that the cows subjected to a GM diet likely suffer from liver, kidney, and muscle damage (Krüger et al. 2011, 188).

Similarly, worrisome health problems have also been reported in a mice study that includes the health effects of a GM diet on the heart, adrenal glands, spleen, and haematopoietic system (de Vendômois et al. 2009, 717). Currently, the same kind of corn and soybeans is said to be fit for human consumption and it is widely used in animal feed for cows, pigs, turkeys, chickens, and other farm animals. Unlike most developed nations, nutritional labels in the US are not required to specify if any of the ingredients listed contain GM ingredients.

RNA exchange with bacteria and virus
The risk of gene fragmentation and cross contamination across plant species, as well as with virus and bacteria, threatens the stability of the genetic code and could have unforeseeable consequences. Currently, it is impossible for us to predict if the insertion of foreign genes could result in corresponding changes in protein synthesis, thus leading to variable nutritional levels or the appearance of new allergens and toxins that could prove harmful to our health (IRT 2013).

While the working assumption is that we should not be afraid of this new technology because new techniques that deal with known problems are being developed daily (Cressey 2013), we must remain cautious as major biotechnology gaffs come to light. A notorious case was discovered between 2012 and 2013. As of early 2013, there were a total of 86 commercially available varieties of GM plants in the US, including corn, soybeans, cottonseeds, and other species. It was found that 54 out of these 86 varieties were contaminated with fragments of the gene VI from the cauliflower mosaic virus (CaMV). The affected varieties include biotech market leaders such as Roundup Ready soybeans (40-3-2), MON810 corn, and the NK603 maize used by Séralini et al. (2012, 4221) in the study mentioned in the previous section (Latham and Wilson 2013).

Gene VI is known to have the ability to become active on its own. The genes of plant and animal viruses are sufficiently similar to allow a plant that has been altered with animal genes to become susceptible to an animal virus infection (Latham and Wilson 2013). The main function of Gene VI is to silence the expression of other genes. This is necessary for a virus because plants and animals have defense mechanisms against viral infections, so to effectively infect an organism, the defense mechanisms of the host must be weaken or nullified. Previous studies indicate that “in general, viral proteins that disable gene silencing enhance infection by a wide spectrum of viruses” (Latham and Wilson 2013). So the potential to have gene VI expressing in GM crops exists, and it would make GM plants more vulnerable to viral disease. But the truth is that we are probably set to find out the consequences of this gaff the hard way.
Biotech industry insiders have argued to ease the safety concerns of some that Bt toxins, as well as other proteins found in GM foods, are irreversibly denaturalized during common cooking procedures, thus leading to permanent loss of protein function (Hammond et al. 2013, 32). However, a ground-breaking Canadian study stands in stark contrast to the assumption that Bt toxins would no survive the human digestive tract. Aris and Leblanc (2011, 530) reported that measurable amounts of Bt toxins were identified in the blood serum of 93% of pregnant women, and in 80% of umbilical serum of the fetuses participating in the study. This finding is not consistent with the claim that the Bt toxin is denaturalized during cooking and digestion, because at least a portion of it remains intact, is absorbed into the bloodstream, and it can even be passed on to the fetus.

What “I Say” about the Real Harvest of GM Crops

GM crops were introduced as an advanced and novel way to keep at bay one of mankind’s oldest fears: famine. Available land resources are limited, and most countries recognize the need to manage arable soil in a sustainable way to ensure that current and future generations will enjoy the pleasure of going to bed with a full stomach. The overwhelming success of GM crops in the past two decades can be summarized as the result of ease of use, higher profits in the short term, and the promise to address the ancient challenge of feeding a hungry and growing population. Did we finally find a lasting solution to guarantee food security? Or, did we buy into the illusion created by too-good-to-be-true corporate marketing schemes?

Jacobsen et al. (2013, 651) rightly point out that our generation was asked to choose between betting on GM crops or protecting the legacy of genetic diversity that we inherited to face growing food demands on the land. So far, it appears that we have largely chosen to place our hopes in GM crops based on the way research funds have been distributed in developed nations. The main problem is that using natural agricultural biodiversity does not limit the potential to use biotechnology to address future issues, but the opposite is not true. For instance, it has been reported that GM corn pollutes natural varieties by means of cross-pollination, and a multitude of cases have been analyzed. A notorious case is the discovery of transgenic DNA fragments in wild corn grown in rural communities in Oaxaca, Mexico (Gilbert 2013). The finding managed to upset a large segment of the Mexican population because corn is one of the main legacies of the Mesoamerican culture and probably influenced the court ruling that suspended all GM corn field trials in Mexico (Yucatan Times 2013). Pollution of native varieties is a serious problem because it could lead to irreversible damage if GM genes are allowed to spread without control.

So, in the face of irreversible loss of genetic diversity, can GM crops feed the world? A study on GM corn and soybean yield trends across the US from 1964 to 2010 shows that GM corn production probably caused an increase in actual yields and is projected to maintain an upward trend from 2011 to 2030, somewhere between 26 to 32%. This is a very modest projection of sustained yield increments because biotech industry insiders estimated yields 100% higher by 2030. The same study found that the trend for GM soybeans would be to remain flat or decline slightly. These findings are based on realized yields in many counties across the US and not on yield estimates based on trial field performance (Xu et al. 2013, 742). To the contrary, application of Agroecology’s principles, such as using beneficial trees, plants, insects, and animals to enhance the soil and protect crops against pests, has shown to increase yields from 80% to 116% in projects across 57 developing countries (de Schutter 2011).

While it seems unlikely that GM-based farming would be able to live up to the promise of eliminating world hunger, some still defend its use based on the idea that facilitates farming and its products are also undistinguishable from traditional agricultural commodities. It has even been suggested that safety testing should be simplified or eliminated to cheapen research cost, accelerate production rates of GM varieties, and open up the access to emerging markets in developing countries (Herman and Price 2013). However, a number of adverse environmental problems have been observed, and Hilbeck et al. (2011) include some examples in their literature review:

1.Grass hoppers feeding on Bt corn can become toxic to chrysopid predators. A higher mortality of chrysopid predators who naturally keep in balance the population of grass hoppers may lead to an infestation of grass hoppers.
2.Butterfly caterpillars feed on non-target weeds growing primarily in GM oilseed rape fields. Widespread application of herbicides kills the non-target weeds and the population of butterflies drops due to lack of food.
3.GM potatoes have an altered starch composition; there is no amylose present, just amylopectin. The higher availability of amylopectin has an effect on the virus-transmitting aphids feeding on it. Then, the growth in the aphid population will result in a higher presence of viruses and neighboring crops will likely become infest.

A review of animal feeding studies indicates that about 150 safety studies were performed on target animals. However, the same publication acknowledges that these studies do not have sufficient endpoint parameters, such as the weight of inner organs, status of the gastrointestinal tract, and histopathology (Flachowsky, Schafft, and Meyer 2012). A pig study was later conducted observing all these endpoint parameters, and it reveals considerable gastrointestinal and reproductive problems in pigs (Carman 2013). However, there is a disconcerting trend of attacking, discrediting, and withholding research funds for research studies critical of GM biotechnology, so in depth analyses of health problems in animals and humans are rare in the scientific literature.

Jeffrey Smith is a journalist and director of the Institute for Responsible Technology. Smith (2004) wrote an article that details how some respected scientists like Arpad Pusztai (formerly at the prestigious Rowett Institute for Nutritional Research), virologist Terje Traavik, epidemiologist Judy Carman, and biophysicist and geneticist Mae-Wan Ho were personally attacked after presenting research data that cautions society against the unrestricted use of GM crops. This list cites only a few well-known examples of scientists who lost their job or had their credibility questioned after manifesting concern over the risks associated with GM food consumption.

More recently, Gilles-Eric Séralini suffered the same fate after publishing a review on liver and kidney toxicity of MON 863, MON 810, NK603 corn varieties (Séralini et al. 2011, 1). However, Séralini’s response to the attacks was different; he sued his main detractor Marc Fellous, chairman of the French Association of Plant Biotechnologies. Séralini’s lawyer was able to prove in court that Fellous registered biotech patents in Israel that were later sold to third parties, such as Aventis. Fellous was unable to portray himself as an unbiased scientist after his personal connections to the agribusiness industry were exposed. As a result, Séralini won his case in court and vindicated his position (Baudouin 2011). At the same time, Professor Séralini was able to secure research funding to conduct his now famous two-year long study on rats without interference. The data collected reveals that rats eating a diet based on MON810 corn developed large tumors and other serious health problems (Séralini et al. 2012, 4221). These new findings erupted into a more furious battle that has not been settled.

Figure 2 depicts the results the toxicity study in rats performed at the Molecular Biology research laboratory of Professor Séralini, at the University of Caen, France. Again, this is the only comprehensive long-term toxicity study of GM corn to date; it was carried over a period of two years, which is the typical lifespan for a rat. It is quite clear that the animals developed large tumors, and their bodies seem deformed as a result. While the human diet is not entirely based on GM corn, the reader may consider if long term consumption could result in negative health effects, including kidney and liver damage (Séralini et al. 2012). Readers might also wonder about the health effects of eating animal products derived from farm animals raised on a GM grain diet. Currently, the diet of most pigs, cows, turkeys, and chickens in the US is based on GM corn and soybeans.

Figure 2, “Tumors in mice caused by exclusively eating GM corn”

(Source: Photo by Poulter 2012, http://www.dailymail.co.uk/sciencetech/article-2205509/Cancer-row-GM-foods-French-study-claims-did-THIS-rats–cause-organ-damage-early-death-humans.html)


In sum, as the evidence of adverse environmental effects and negative toxicological interactions continues to grow, it is intriguing to compare this research data with the fact that biotech giants continue to assure the public that their agricultural model is sustainable, and that their products are safe to eat and nutritionally equivalent to traditional crops. In the mean time, the trusting public accepts the official version… why would they lie to us?

Clearly, there is evidence to support the allegation that the wildly believed claims of the biotech industry may be based on marketing talking points, not on solid scientific research. Careful scrutiny is necessary, but it is rarely performed due to lack of research funding, and it is also discouraged by external pressures from powerful economic and political groups. It is unlikely that independent scientists will be able to fully address the complex multidisciplinary environmental impact and health effects derived from the widespread use of GM crops, so a solution seems elusive unless the general population becomes aware of the seriousness of the problem and takes an active roll. The research needed to prove every point of concern beyond any doubt would be very costly and time consuming; therefore, it would require a firm commitment from research teams and governments around the globe. Not surprisingly, GM producers rely on the fact that this is unlikely to happen in the current political climate, so they can afford to sit back and see their optimistic projections continue to go on unchallenged in the public arena, since the US government established a very low threshold to accept their homemade safety claims.

A change in current trends could occur if a large segment of society becomes organized and confronts politicians and business leaders to demand answers and corrective action. Adding mandatory labeling of GM-derived ingredients to nutritional labels could be a step in the right direction. The public may also opt to vote with their checkbooks and commit to consume non-GMO and certified organic products, since increasing demand for this type of food will send a strong message to food manufacturers, who in turn will transmit the information to food producers.


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1- I evaluated the reliability of the sources based on my own judgement and personal experience. The responsibility for the reliability of the source materials in the paper will automatically transfer to whoever reads my paper if they wish to use the information referred to for their own research.

2- Whatever I say in my discussion and conclusions is based on my own understanding of the source material. I made an effort to use rigorous research techniques to analyze all data.