Evaluation of the Pros and Cons of GMOs

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18th May 2020 Environmental Sciences Reference this

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Review on the pros and cons of GMO: productivity, profitability, environmental impacts and human health impact

Abstract

Genetically Modified (GM) seeds has struck controversy for decades. Despite the potential to increase crop yield and ease the food demand from a growing population, there are various arguments over the overall effects of GM food on the environment human health. Although the initial implementation of GM crops had resulted in an increase in production and environmental benefits due to farm chemical being used and more conservative farming practices, these benefits are being diminished due to resistance build-up in the target species. There is also a lack of public study to draw any relationship between the consumption of GM food and public health. Any discussion on the possible benefits and risks of GM food on human health are based on predictions without concluding evidence. With more research in the GM field to include more beneficial traits into seeds, it is necessary for regulatory bodies to remain vigilant in commercialising new GM crops to ensure that there is no risk on the environment and human health associated with the future patch of GM crops.

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1.      Introduction

Mankind have altered plant genes for millennia to produce the best-fitted food with high-energy value [1]. The earlier efforts involved selective breeding crops with desirable traits. The DNA recombination in offspring was random and this process often took decades, due to repeatedly yielding crop variations with undesirable and unforeseen characteristics [1]. Agricultural biotechnology has drastically shortened the breeding process by using genetic engineering to minimise breeding time and uncertainty and allow transfer of traits from distantly related plants. Genetically Modified Organism (GMO), the product from agricultural biotechnology is gaining more attention due to the increasing population in the world.

There are 7 billion people in the world today and this number projects to exceed 11 billion by 2100 [2]. In view of this, many believe that GMO is a promising technology to counter the global hunger crisis associated with the booming population [3]. There are many controversies surrounding the application of GMO. While some researchers believe that GMO is a solution to the world hunger issue and carries other benefits such as improving the environment via more sustainable farming practices [4, 5], others believe that the technology lacks public studies on the possible risks to humans’ health [1]. The vast adaptation of GM crops has also resulted in resistance built up in some weeds and insects, which may in turn create more environmental issues [6]. This paper aims to provide a literature review on the pros and cons of genetically modified crops. The paper will focus on evaluating the productivity and profitability of GM crops, the environmental implication of adopting GM crops and the human health impact of GM crops.

2.      Productivity and profitability of GM Crops

One of the main benefits of GM seeds often mentioned in literature is the rise in the productivity and profitability levels for farmers. GM crops resistant to herbicides and insects can drastically shorten the crop management process and minimise crop losses, resulting in higher yield [4]. According to Mannion & Morse (2013), GM variety of cotton, maize and soybean increased yield by 15%, 7% and 20% respectively. This increase in yield from GM crops was also observed in other studies [7, 4]. The Economic Research Service (ERS) of the United State Department of Agriculture (USDA) reported a significant positive correlation between adoption of pesticide and herbicide GM crop seeds and crop yields.

While it is evident that GM crops increase the yield of farmers, this increase in production does not always translate to an increase in profit. According to Barrows, et al., (2014) GM crops only brings in profit when the crop losses avoided by GM seeds compensates the higher costs of GM seed. This effect is demonstrated in Figure 2. The land quality is plotted against the profit per acre of farm land. The left side depicts land of high quality with low pest pressure and the right side shows land of low quality with high pest pressure. Line CD depicts the profit per acre as a function of land quality for genetically engineered seeds and line AB depicts the profits per acre for conventional farming. From the diagram, in areas where the pest pressure is sufficiently low (i.e. left side), the traditional method produces higher profits, as crop losses prevented by genetically engineered seeds are unable to cover its high cost. Conversely, as the pest pressure increases, the profits from using genetically engineered seed increases. In general, genetically engineered seed usage is anticipated to enhance crop supplies by creating incremental yield gains along the intensive margin and by promoting production along the extensive margin on land, which otherwise would not generate any output.

Figure 1: Damage control model by Barrows et al. (2014). Land quality is decreasing along the horizontal axis and profit per acre is measured along the vertical axis. Line AB and CD illustrates the profit per acre of farm land for traditional and genetically engineered crops as the land degrades.

3.      Environmental Impact

Herbicide-tolerant and insect-resistant traits are the two most common traits found in GM crops (responsible for around 99% of the GM seeds) [8]. The environmental benefits and risks discussed in the next subsection will be centred on these two traits.

3.1.  Pest-tolerant GM crops

The biggest advantage reported in literatures of pest-tolerant crops reported in studies is the reduction and elimination of pesticide usage [9, 10, 11]. The introduction of Bacillus thuringiensis (Bt), which is toxic to most agricultural pests, has greatly reduced the usage of pesticides in GM farming practices [1]. GM crops that release this toxin needed little or no additional pesticide usage even when the pest pressure is high [12]. This reduction in pesticide usage from the introduction of this gene into the crops has led to a greater conservation of useful insects and assist to preserve other non-target species (possibly expanding on-farm varieties in insects and pollinators) [4]. On top of that, the shrink in pesticide usage also benefits the environment indirectly from reduction in pesticide runoff [13] i.e. reduced land and water contamination.

Despite the vast benefits of pest-tolerant crops, there are also concerns with resistance build-up in target species from repeated use of the GM crops with the similar toxin [14]. According to the National Research Council (2010), within the first 14 years of adoption of pest-resistant crops, three pest species had already developed resistance towards Bt toxin. Bagla (2010) had reported pink bollworm becoming immune to the first generation of GM Bt cotton in India. Similar pest resistance was reported in Spain, Australia, the United States and China [6]. This growing resistance to GM Bt crops could result in increasing application of pesticides, which in turn defeats the purpose of GM Bt crops.

3.2.  Herbicide-tolerant GM crops

Unlike pest-resistant seeds, which act as substitutes for pesticides, herbicide-tolerant seeds work hand-in-hand with herbicides (most commonly, glyphosate). This allows the selection of environmentally-friendly alternatives for the more toxic chemicals used during traditional farming [1]. While the overall use of the herbicide might not be reduced, the main environmental benefits from using herbicide-tolerant seeds reported in most papers were based on the fact that a noxious herbicide previously used had been replaced with a milder one (glyphosate) [15, 16]. Another benefit frequently reported was the reduced tillage operation [11, 17, 1]. Tilling is a mechanical method of weed control that releases carbon from soil, causes soil erosion and increases farm runoff, which is responsible for excessive nitrification, in turn causing eutrophication. Such eutrophication causes these areas to be inhabitable for organisms due to low dissolved oxygen level (e.g. dead zones in the Gulf of Mexico) [1]. The adoption of herbicide-resistant crops replaces the pre-emergence tilling operations with post-emergence glyphosate application [18]. The reduction in tillage operations also indirectly lowers the need of fuel to operate farm machinery, which reduces both farmers’ costs and greenhouse-gas emissions.

Similar to pest-resistant seeds, herbicide-resistant seeds also face issues of resistance build-up in target species. Duke and Powles (2009) estimated that minimally 10 species of weeds have evolved to be immune to glyphosate in herbicide-tolerant farms in the United States. This resistance build-up was exacerbated by extensive farming of herbicide-tolerant crops and almost exclusive dependence on glyphosate to control weed [11]. This has resulted in increasing application of glyphosates to counter reduced efficacy and sometimes, glyphosates are replaced by other herbicides. However, these herbicides are often more harmful as mentioned earlier [1]. This resistance build-up in weeds is diminishing the environmental benefits that can be derived from the herbicide-resistant crops.

4.      Human Health impact

Many researchers reported that GM crops may positively affect human health by reducing the exposure to pesticides [19, 20] and by altering herbicide usage towards glyphosate [21]. However, these claims lack experimental data and are based on assumptions. There is a lack of public studies to draw any relationship between consumption of GM food and human health. Although Seralini et al. (2013) conducted a public test, the result has garnered criticism and scepticism and were often considered unreliable to many other researchers [22]. However, it is undeniable that the commercialised GM crops have gained regulatory approval by qualified authorities such as European Food Safety Authority in Europe and Food and Drug Administration in the United States, as being safe for human consumption  [3]. On the other hand, enhancements of GM crops that provide direct health benefits such as higher level of fatty acids, essential amino acids and nutrients and lesser allergens, hold promises but have yet to be commercialised [23, 24, 25]. A huge issue facing the advancement of GM crops is activist campaigns. For instance, Golden Rice is among the best known examples of a bio-fortified GM crops that contain vitamin A, which can potentially benefit many children who suffer from blindness due to vitamin A deficiency [26]. However, the project was hindered by the protests from activists. Although Golden Rice was announced in 2005, the first approval as food in New Zealand, Australia, Canada and the USA only came in 2018 [27].

The concerns from the activists were not unique. Many researchers also feared the possibility of unexpected side effects from the consumptions of genetically modified food. For instance, some worried that the selection for antibiotic-resistant genes in food could result in diminish efficacy of therapeutic antibiotics [1]. Some also feared that the antibiotic resistance may escalate from crop plants to soil or intestinal microorganisms. Despite no evidence of such transfer arising [28], the long-term repercussions of consumption of genetic modified food is still uncertain.

5.      Conclusions

Genetic modification is compelling because it brings novel traits into crops by recombinant DNA technology. Although GM crops have been adopted rapidly in some countries across the globe, only a small number of traits have been engineered into GM crops. The two main traits are insect resistance and herbicide tolerance. Nevertheless, farmers who use GM crops have gained from the operational and production benefits they furnish. Current GM crops have also aided the practice of sustainable farming, particularly the reduction in tillage. However, the adoption of GM seeds is not without risk. The rapid and frequent adaptation of GM seeds with the similar traits has accelerated the evolution of herbicide-resistant weeds and pesticide-resistant insects. This in turn creates additional operation challenges and costs for farmers. Furthermore, the additional usage of herbicides due to resistance build-up in weeds and the potential risks of these pesticide-resistant pests have diminished the environmental benefits brought about by GM crops. The GM crops commercialised at present have all been deregulated and marked as sage to human health and the environment by various regulatory agencies across the globe, such as the European Food Safety Association. Despite that, criticisms that GM and GM crops lack public research on the potential risks to human health still remain. However, the vast operational benefits for farmers and the potential to ease the food shortage problem mean that GM crops will continue to be developed. The novelty of such technology and its capability to bring almost any trait into crops require regulatory bodies to remain dedicated in diligence to prevent the deregulation of GM crops that may pose risks to the environment or human health.

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