Genetic modification, as the name suggests, is a biotechnological process by which the genetic material in an organism such as plants is altered in a manner that does not take place in the nature or via nature-influenced recombination. Such organisms which are called as the Genetically Modified Organisms or GMOs find immense practical applications in the modern times. They are used extensively for carrying out medical and biological scientific work, are used to manufacture new pharmaceutical medications and importantly, are used in agriculture to produce good quality crops. The reason why genetic modification has gained prominence in agriculture is because it makes a leeway for the production of improved quality crops in a shorter time-span as compared to the natural selection method (Verma et al. 2011).
Genetic modification of plants or genetic engineering is essentially the process by which foreign genetic material i.e. genes from other sources like plants and/or animals that carry the desirable traits, is introduced into a particular plant that is used as a food source. This process is said to improve the quality of the food crop in many ways. The genetically modified foods hold great promise for cultivators in particularly the developing countries, where the use of advanced agricultural technologies to enhance output is less as compared to that in the developed world. Through the cultivation of genetically modified crops, farmers from the developing nations can hope for better yields with minimum inputs in terms of the amount of pesticides and fertilizers used. They can even expect more harvests in a year since the GM crops grow faster (Key et al. 2008).
Another very important benefit of genetic modification of plants is that it considerably increases productivity of food. These crops are able to survive hostile growth conditions such as salinity, drought, extremes in temperature etc. and hence loss of yield is minimized with the GM crops (Key 2008). Thus, GM crops ensure greater food availability for the millions living around the globe. Additionally, since crops are genetically modified to make them more nutritious, consuming such foods also ensures better nutrition for the people (Verma et al. 2011). In other words, genetic modification of plants for food purposes could be an answer to widespread malnutrition in several parts of the world.
However, despite genetic modification of plants for food purposes conferring these many vital advantages, it has been the subject of much debate between scientists and consumers. There are many NGOs and other organizations that have been quite vocal about their criticisms over the GM foods. Many of the NGOs have attacked the GM crops by saying that if they do not taste good and are unsafe for consumption, how are the engineered foods to help alleviate malnourishment in the developing world (Key 2008). In particular, the opposition to the GM foodstuffs is greater in the EU where the general public opinion is that the risks of GM crops far outweigh their benefits. In contrast, in the US approximately 60% to 70% of the processed foods available in the markets contain GM ingredients (WebMD [date unknown]).
Much of the opposition to the GM foods focuses on the safety aspect of such food materials. In light of this, the question that comes to the forefront is- what are the disadvantages of genetically modified foods that render them unsafe for regular consumption?
Disadvantages of Genetically Modified Foods
As stated earlier, briefly put genetically modifying a food crop involves introducing a gene foreign to the plant in it. The gene thus introduced typically carries in it the traits that are desired in the food crop such as drought, salinity or disease resistance and faster growth. The foreign gene could also be one that improves the nutrient composition of the food crop (UMMC 2013).
The process by which food crops can be genetically altered is termed as genetic engineering. This method essentially involves the manual addition of the desired DNA material to a plant cell. The method, also known as transformation, requires the gene material carrying the desirable traits to be physically removed from one organism and be introduced in the DNA composition of the plant. For this, the desired portion from the foreign DNA is first cut using the restriction enzymes. This cut DNA is then combined with a plasmid to generate the recombinant DNA. The recombinant DNA is then allowed to be taken up by a vector or carrier cell, which is then cultured to generate several copies. Plant cells are then mixed with the vector cells under controlled conditions to allow for the transfer of the plasmid DNA into the chromosomes of the plant cell. This way the new DNA or transgene becomes a part of the host plant’s genetic material and the plant then begins to exhibit these improved traits (Jones 1999).
Some examples of crops that have been genetically altered using the genetic engineering technique are Bt Cotton, Bt Maize and Bt Brinjal that show improved pest resistance, Golden rice that contains the beta-carotene gene and hence higher Vitamin A content and potatoes that soak up less oil while frying. Scientists have even attempted to genetically alter vegetable oil sources such as soybean and canola, as a means to producing healthier oils (Verma et al. 2011).
However, while the technique on the whole sounds as if it can generate miracles in terms of crop yield and food production, it also raises some ethical dilemmas that pertain to its negative effects. Broadly, the negative impact of genetically modified foods can be categorized as those affecting the environment and those affecting human health. According to Key et al. (2011), there are three aspects of genetic engineering technique that have given rise to a debate on how safe the procedure is for human and environmental health. The three aspects are as follows-
- Using selected markers as a means to identifying the transformed plant cells
- The possibility of an extraneous gene i.e. genetic material other than the one desired being transferred into the host plant
- The risk of unwanted mutations occurring in the genetically modified plants by virtue of the tissue culture techniques used to produce them and the rearrangement of the gene material around the site of insertion.
During the transformation process, typically a selected marker gene that confers for instance, antibiotic resistance is transferred together with the gene carrying the desired traits. This step is done to permit GM tissue discrimination. It also allows for regeneration of the transformed plant. While the step is no doubt important, critics of this technique argue that it is inherently unsafe because it adds to the risk of spreading resistance to the antibiotic in the bacterial population, both in the soil and in the human intestines. However, there are studies which show that the probability of antibiotic resistance developing in the bacteria is low and hence the step of including a selected marker gene poses negligible hazards. As such, today there are many other selection strategies available that eliminates the need for a selected marker gene to be used during transformation (Key et al. 2008).
This leads to the second aspect of the risk genetic engineering poses viz. the possibility of an extraneous DNA being transferred to the host plant cell. Critics fear that although DNA per se cannot act as a health risk to GM food consumers, there is always a chance of some harmful DNA getting transferred along with the desired gene (Key et al. 2008). This in effect, will render the GM crop more dangerous for common consumption.
Finally, it has been widely claimed that with the GM crops there is a high risk of unwanted mutations occurring in the host plants. Experts are of the opinion that such mutations might occur during tissue culturing. It might also lead to certain somaclonal variations that may not be desirable. For example, there is a chance that along with the insertion of the desired DNA, there might be some endogenous changes occurring in the host plant cell gene that might reduce nutrient levels or enhance those of toxins and allergens that can pose serious health risks to humans (Key et al. 2008). Verma et al. (2011) state that this risk of unwanted mutations in genetically modified food crops has the potential to create unpredictable alterations so that the actual effect of the technique on the host plant may not be known, maybe even until after widespread consumption.
Environmental Risks posed by Genetically Modified Foods
Large-scale production of genetically modified plants can influence the environment adversely in four ways (Key et al. 2011)-
-It increases the risk of sexual hybridization of GM plants with the non-GM ones.
- It increases the risk of the GM plants themselves becoming ‘superweeds’ upon cross-breeding with weeds.
-It might decrease pesticide-effectiveness if pests become resistant to pesticide-producing Bt crops.
-There is also a risk of the specialized growth conditions of the GM crops posing a danger to wildlife population in the locality.
-It promotes increased herbicide use, which increases chances of environmental pollution.
One example of GM crops posing a danger to the environment is the Bt Maize that proved harmful to the existence of the Monarch butterfly. A study on this case in 1999 found that the maize crop that was modified to express the Bt toxin, an insecticide, was affecting the larvae of the butterfly species. The study reported that the larvae which survived on milkweed that had the Bt maize pollen dusted on it consumed less of the weed, grew at a slower rate and showed increased mortality (Key et al. 2008). Similarly, the UK Farm-Scale Evaluations study observed that the wildlife around GM fields was markedly reduced as compared to that around non-GM fields (Defra 2007). It was also found that the GM plant, creeping bentgrass, an herbicide-resistant plant, that was planted in Oregon, USA, ended up growing wildly extending to 3.8km outside of the designated cultivation area (Reichman et al. 2006).
Human Health Risks posed by Genetically Modified Foods
A number of human health risks of GM foods have been reported by different investigations. Several studies have shown that GM foods can cause toxic reactions in the digestive system. In one study it was reported that the GM FlavrSavr tomato led to the development of stomach lesions in experimental rats and could lead to hemorrhage in the humans (Pusztai 2001). Similarly, it was found that mice that were fed engineered potatoes developed abnormal cells and even showed proliferative growth in the small intestines (Fares and El-Sayed 1998). GM potatoes and the GM Roundup Ready soybeans have also been found to cause liver damage (Key et al. 2008).
Not only do the GM foods adversely affect the digestive tract, they also have been demonstrated to cause damage to other organs including the kidneys, brain and the reproductive organs. On the whole, these foods are observed to increase mortality rates in experimental animals (Key et al. 2008).
Among the different health hazards posed by GM foods, one that has been in the limelight is the effect on the immune system and the possibility of provoking allergic reactions. Inflammatory reactions from GM foods like potatoes, peas and soybeans have been reported. In particular, scientists studying the GM soybeans found that it had an unanticipated protein in it that had the capacity to bind to IgE antibodies. This, the researchers said could cause the GM soybeans to trigger intense allergic reactions (Verma et al. 2011).
Another cause for concern with the GM food crops is the presence of the Bt bacterial DNA in them, which is not only toxic, but also has been reported to be incompletely eliminated during heat processing and digestion. Considering that there are many Bt crops available today, it does seem as if the human gut might soon be transformed into a pesticide factory with it producing the Bt-toxin (Verma et al. 2011).
Safety of Genetically Modified Foods
But probably the biggest disadvantage of the GM food crops is the fact that there is inadequate scientific investigation into the health risk they pose. Also, the safety test techniques available are insufficient to correctly measure the harm that the crops may cause (Pusztai 2001).
While there are strict regulations and regulatory agencies such as the EPA, FDA and US Department of Agriculture in place that review the safety of GM foods before they are put into the market, the testing methods themselves are inadequate. For one thing, testing the safety of crop-based foods is more difficult than testing how safe food additives or drugs are. Also, the common approach to GM foods safety testing is to compare GM and non-GM crops for their composition. If upon comparison, no significant difference is found between the two, they are considered as ‘substantially equivalent’ and the GM crop is declared as safe for consumption. However, this concept itself is unscientific and has no proper definition (Pusztai 2001).
Finally, economic disadvantages also exist with the GM crops with consumer advocates worrying that farmers in the developing world might not be able to afford the expensive GM seeds. There is also increased risk of large-scale crop failure as the genetic composition of a GM field is identical i.e. should a pest attack one plant, the entire crop is at risk of being damaged (Verma et al. 2011).
On the whole, as long as disadvantages of GM foods exist, these crops might not find widespread public acceptance unless all of them are addressed. Only when the cons of genetic modification of plants for food are sorted out will the process genuinely help to alleviate food crisis and nutrition challenges throughout the world.
Literature Cited
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Fares NH, El-Sayed AK. 1998. Fine structural changes in the ileum of mice fed on endotoxin treated potatoes and transgenic potatoes. Nat Toxins. 6: 219-233.
Jones L. 1999. Genetically modified foods. BMJ.318 (7183):581-584.
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Reichman JR, Watrud LS, Lee EH, Burdick CA, Bollman MA, Storm MJ, King GA, Mallory-Smith C. 2006. Establishment of transgenic herbicide-resistant creeping bentgrass (Agrostis stolonifera L.) in nonagronomic habitats [abstract]. Mol. Ecol. 15 (13): 4243-4255. In: PubMed [database on the Internet]. Washington DC: NLM [cited 2006 Nov.] Available from: http://www.ncbi.nlm.nih.gov/pubmed/17054516
UMMC [Internet]. 2013. Baltimore, MD: University of Maryland Medical Center; [updated 2013 May 31]. Available from http://umm.edu/health/medical/ency/articles/genetically-engineered-foods
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WebMD [Internet]. c2005-2014. WebMD; [cited date unknown]. Available from: http://www.webmd.com/food-recipes/features/are-biotech-foods-safe-to-eat
