MONDAY, 18 DECEMBER 2023
‘Genetic engineering’ is a broad term, ranging from modifying existing genes to introducing a gene derived from other species. The term emerged as scientists began to recognise ‘gene’ as a unit of inheritance in the early 20th century. If we understood the role of each gene and modulated them, some imagined, we could design an organism. Genetic engineering was fulfilling this dream: improving crop quality and yield. From the late 20th century, the emergence of genetic engineering brought genetically modified (GM) crops to the market, and with it, anti-GM sentiment sometimes as extreme as vandalism and lawsuits. Can we be confident in GM crops? Which societal and scientific challenges should we be mindful of?The benefits that GM crops bring us are solid. Herbicide- and pest-resistance, the modifications first engineered into crops, are still widely used. They aided the massive increase of crop yields during the so-called ‘’Green Revolution’’ in 1950-70 along with employing chemical herbicides and pesticides. Herbicide-and pest-resistance are still widely used. In 2020, Kenyan farmers lost their crops to locusts, a problem insecticidal GM crops could solve. Increased food production generally leads to a better living standard. In the 1950s UK households spent about 33% of their income on food whereas today the figure is around 8%, now having more spare money to spend. Furthermore, modulating the relevant genes, we can produce larger fruits, delay ripening, and change the colour or shape. Significantly, a GM variety that produces vitamin A producing rice, called “Golden Rice”, reduces incidence of childhood blindness due to malnutrition in underprivileged regions. Such beneficial genes can be homologs of genes identified in close relative crops. There are also efforts to diversify the genetic pool which has gone through a bottleneck due to selective breeding. As such, GM technology can help prevent disease through malnutrition, increase food security and help those at greater risk of food poverty.
Moreover, the future of genetic engineered crops looks bright. The recently developed gene editing tool, clustered regularly interspaced short palindromic repeats system (CRISPR-Cas9), is sophisticated yet convenient enough that labs can simply order the kit to insert, delete or mutate a single gene locus or multiple loci. This greatly lowers the barrier of gene engineering as the expertise is not required; so CRISPR effectively revolutionised genetic engineering and broadened the potential of GM crops.
However, some alleged advantages of herbicide- and insect-resistant phenotypes are controversial. Pesticides secreted directly by the pest-resistant plants will be more effective than applied pesticides which will be washed away. However, GM crops have also introduced some chemicals to our food: for instance, growing herbicide-resistant crops to replace tiling with herbicide treatment encourages careless use of herbicides, among which the most widely used is glyphosate. Problematically, the International Agency for Research on Cancer (IARC) classified glyphosate as a probable human carcinogen, finding “strong” evidence of genotoxicity. Glyphosate is used on some 80% of GM crops which means that GM technology is indirectly leading to widespread exposure to potential carcinogens.
One of the earliest GM crops was insect-resistant crops producing Bt toxin, which specifically acts on insect gut receptors but not on humans or animals preying upon the insects. The Bt toxin gene is inserted in a variety of crops, especially widely used among maize and cotton. Now Bt toxin has been extensively used for pest control for nearly a century and is approved for organic farming. The safety of Bt crops have been comprehensively verified. However, this is not the case for the majority of GM crops, when the industry is churning out varieties upon varieties. Some of the GM crops may bear unknown health risks, which might not have manifested yet. There are perils of rushing into new technologies that have not been extensively tested for safety.
In her book Silent Spring, Rachel Carson highlighted the chronic toxic effect of DDT, which accumulates in predators and manifests only in the long term. DDT was excessively used, believed to be safe based on short-term experiments that showed no significant results. Indeed, we need close preclinical studies and robust regulatory science to ensure healthy development of GM technologies. This is especially the case due to the complex regulation of gene expression that we do not fully understand. Scientists are now aware that ‘genes’ are not discrete and phenotypes are regulated through a complex of molecular interactions. Even CRISPR, a recent tool also called “genetic scissors” due to its specificity in recognising target sites, shows high risk of off-target effects: unintended mutations can be made in similar sites, or the modulated region may participate in regulation of expression of other genes.
We should also consider potential societal consequences of commercialised GM crops. Large agricultural corporations, such as Monsanto and Syngenta, are the main patent owners of GM crop varieties and are often exclusive in their ownership. While farmers often salvage seeds to sow the following year, GM seeds are sterile so must be purchased every year. In an industry with marginal profits for farmers, having to pay for seeds every year poses yet another financial burden. Corporations will benefit at the expense of middle-class citizens; and at its worst, weakening of middle class farmers may destabilise economic structure in an agriculture-based country. For instance, the U.S.A-based agricultural corporation Monsanto’s influence on Indian agriculture has been controversial. Commercialised in 2002, Monsanto’s GM cotton replaced local cotton varieties at a high rate, homogenising the vegetation. Seed monopoly ladened the financial burden on the farmers, having to pay a fee to the company every year. Monsanto was blamed for the raised suicide rate among Indian farmers.
So how can we be aware of the potential dangers of genetic engineering and provide a social safety net for individual farmers? To be commercialised, preliminary studies are required by governmental institutions of respective countries, which should take place in a closely monitored environment. Novel genes or technologies are often contested. For instance, a massive field trial in India demonstrated the usage of novel gene (GURT) may be defective, causing death of livestocks that consumed the variety. This event elicited public outrage, leading to campaigns against GMO in general in the late 1990s in India. Ensuring safety requires another social aspect of science, regulatory science, which asks the fundamental question: how much evidence is sufficient to believe in a product? After all, the acceptance of a technology comes down to whether the public chooses to consume. While this question is mainly addressed by experts in modern society, we need social consensus on ‘safety’ so that each individual can be aware of what they eat.
Here lies another dilemma: contemporary science is a powerful tool to investigate natural processes but also authoritative, complex, and a point of collision of various interests. Some scientific research funded and published by companies tends to be biassed towards the company. In the 1950-60s, chemical companies lobbied regulatory authorities to undermine the evidence that DDT is carcinogenic. We should ensure that a fair and in-depth scientific analysis can be done through robust regulatory science institutions such as the Genetically Modified Organisms (Contained Use) Regulations (GMO(CU)) of the UK. On the other hand, in an attempt to solve societal issues, multiple social initiatives develop genetically modified crops for the benefit of citizens. The International Crops Research Institute for Semi-Arid Tropics (ICRISAT) is one such non-profit organisation that takes molecular approaches to develop crops suitable for semi-arid tropic farms.
There are risks in using GM crops, both known and unknown. Historic environmental disasters such as DDT should remind us to be cautious of letting our desire for technological progress override our sceptical scrutiny of new technologies, particularly those with far-reaching environmental consequences. We must also face an easily neglected issue for food security: we waste an estimated 30% of food each year worldwide. Perhaps we should tackle this social justice issue as much as we invest in better GM variety. There is no doubt science is a powerful tool that can improve our life, but our belief in science often blinds us from facing the elephant in the room. Scientific development should always go together with societal efforts since science and technology can sometimes bear health and environmental risks.
Hayoung Choi is a second-year undergraduate studying biochemistry & molecular biology, plant & microbial sciences, and history & philosophy of science at the University of Cambridge. They have a broad academic interest and are currently Workshop team lead at Cambridge University Science & Policy Exchange (CUSPE). Artwork by Biliana Todorova.
