GMOs- how worried should we be?

The US department of agriculture estimates that over 90% of the corn and soy grown in the US is from genetically modified plants. GMOs have been controversial since the idea was first planted (ba-da bing!) in scientists’ heads. A lot more people are eating GM foods than probably realize as it’s estimated that over 80% of food sold in American supermarkets are made from ingredients derived from GM crops1.

So what are these plants which instigate so much controversy? GMOs are genetically modified organisms, meaning crops, plants, and insects whose DNA has been modified, usually to add a gene from another organism. Before genetic engineering, people used a method called selective breeding where they would breed together strains with desirable traits to get even better traits (cows that give a lot of milk or juicier tomatoes, etc.). Now scientists have much more efficient tools to get animals and plants with desirable traits, especially if the desired traits are from completely different species (a milk cow and a juicy tomato plant for example) and therefore can not be bred together.

So how concerning actually are these concerns? Let’s learn a bit more about how GMOs and then I’ll let you decide how concerned to be.

First of all, how are GMOs developed? There are several classic methods of transferring genes to plants, the main ones being Agrobacterium-mediated transformation and particle bombardment.

Agrobacterium tumefaciens is a plant bacteria that is able to transfer a DNA segment into the plant that it has infected in a process called horizonal gene transfer. Usually this transfer DNA segment (T-DNA) causes tumors in the plants, but in 1977, Zambryski et al. replaced the bacteria’s normal T-DNA with another gene, which was the first time that scientists used the Agrobacterium’s natural ability to transfer DNA into plants to genetically engineer plant cells with a specific gene. The gene transferred in this process enters the nucleus of the plant cell where the genetic material is kept and is integrated into the DNA. The only limitation with this method is that Agrobacterium does not infect all plants2.

The second method, called particle bombardment, was developed in 1987 and consists of coating gold or tungsten particles with DNA and then shooting them at plant cells at high speed. These metal particles penetrate the cell wall and some of the DNA coating is integrated into the plant DNA. This is especially useful for species which can not be infected by Agrobacteria2.

CRISPR will soon be a widely utilized method of gene editing as well. It’s been used in labs for gene editing for a decade or so. It’s is a widely used tool in laboratories around the world to edit DNA in a precise manner using a lab manufactured RNA sequence matching the sequence of DNA or RNA you are targeting in the organism. It uses an enzyme called cas9 (for DNA) or 13 (for RNA) which cuts the target DNA or RNA at the matching sequence. This method can be used to change a base in a gene (called single point mutations), delete genes, and insert sections of DNA3. The first CRISPR/cas9 edited produce (a GABA enriched tomato) entered the market in Japan in 20214. And this is just the beginning. Because plants edited using this process by and large are not required to go through the same regulatory processes as the methods used up to now, more and more CRISPR edited produce is going to arrive at our tables. Currently in the pipeline- soybean with enhanced tolerance for salt and drought, mushrooms that don’t brown, and camelina (an oilseed crop, not a camel that dances) with increased omega3 oil content5.

So what is the public so worried about when it comes to GMOs? According to the Center for Food Safety, the 6 concerns they have about these foods are toxicity, allergic reactions, antibiotic resistance, immuno-suppression, cancer, and loss of nutrition. One concern is that transferring genes from one organism to another could be transferring the allergens of one organism to the other. However, scientists are aware of this issue and consequently do not transfer allergenic proteins to other plants. On the flip side, if foods causing common allergies such as peanuts or soybean could be modified to reduce or eliminate the amount of allergy causing protein, this would be a huge benefit to the general population.

There are also concerns about toxicity, but so far no genetically modified foods have been found to be toxic and there is very little evidence suggesting that this should be a concern6. Many people who don’t understand genetics worry about these transgenes somehow being transferred to humans or animals eating GM crops, but once a transgene is safely at home in an organism’s genetic material, it has the same probability as any other natural gene of being transferred to someone eating it, which is pretty small seeing as most of us are not viruses or bacteria in which horizontal gene transfer is more common.

Many people also worry that GMOs have no long term studies to assess safety, only short and medium term studies. However, GM crops have been widely available since the 90’s and so far there have not been shown to be any real safety or health issues.

The more pressing concerns are the environmental and ecological ones, in my opinion. There is definitely a high potential for the genes from the GM crops to be unintentionally transferred to other nearby crops by cross pollination6. When you impart traits that increase survival into a specific plant and then bees or the wind spread the pollen of that plant to other neighboring plants of the same variety, you end up with a bunch of really tough plants that you didn’t necessarily want and that are hard to kill. You have accidentally turned these nearby plants into superweeds. The wind or birds may also spread the seeds of your GM plants into your neighbor’s backyard or into another farmer’s fields. This might require the use of a lot more herbicide just to get rid of the hard to kill wheat growing in your neighbor’s rice paddy for example. You also probably won’t be invited to many neighborhood barbeques if you’re spreading super weeds around town.

Another serious issue is the lack of genetic diversity in GM crops. If everyone starts growing the same lab cultivated species, you increase the risk of the whole species going extinct if that particular crop is vulnerable to a new disease or pest. For example, bananas almost went extinct back in the 50’s when the dominant banana strain, the Gros Michel, was attacked by the Panama Disease. Farmers were able to switch to a different strain, called the Cavendish, before we completely lost our bananas. Of course, now over 99% of exported bananas are the Cavendish banana and in 2019, Tropical Race 4, a new strain of the Panama Disease that does affect the Cavendish had made its way from Taiwan all the way to Colombia. This isn’t solely a GMO problem, of course. It could happen to any non-diverse crop species being grown (as the world saw with bananas). As an aside, I discovered in my research the very important fact that there is such a scientist as a bananologist, though there might only have been one ever (Norman Simmonds).

However, it is not a total free for all and there are regulations in place for producing and growing genetically modified foods (at least those produced via traditional methods). The WHO and the UN’s Food and Agriculture Organization put together a codex of standards and guidelines for food and produce safety (including GMOs)7. In the US, GMOs are regulated by the FDA, USDA, & EPA. In Europe, the European Food Safety Authority (EFSA) regulates them. All genetically modified foods and animal feed are tested thoroughly for health and safety and for potential environmental impact before they’re allowed to be grown. According to the USDA website:

“Crops produced through genetic engineering are the only ones formally reviewed to assess the potential for transfer of novel traits to wild relatives. When new traits are genetically engineered into a crop, the new plants are evaluated to ensure that they do not have characteristics of weeds. Where biotech crops are grown in proximity to related plants, the potential for the two plants to exchange traits via pollen must be evaluated before release. Crop plants of all kinds can exchange traits with their close wild relatives (which may be weeds or wildflowers) when they are in proximity. In the case of biotech-derived crops, the EPA and USDA perform risk assessments to evaluate this possibility and minimize potential harmful consequences, if any.

Other potential risks considered in the assessment of genetically engineered organisms include environmental effects on birds, mammals, insects, worms, and other organisms, especially in the case of insect or disease resistance traits. This is why the USDA’s Animal and Plant Health Inspection Service (APHIS) and the EPA review environmental impacts of such pest-resistant biotechnology derived crops prior to approval of field-testing and commercial release. Testing on many types of organisms such as honeybees, other beneficial insects, earthworms, and fish is performed to ensure that there are no unintended consequences associated with these crops.

With respect to food safety, when new traits introduced to biotech-derived plants are examined by the EPA and the FDA, the proteins produced by these traits are studied for their potential toxicity and potential to cause an allergic response. Tests designed to examine the heat and digestive stability of these proteins, as well as their similarity to known allergenic proteins, are completed prior to entry into the food or feed supply. To put these considerations in perspective, it is useful to note that while the particular biotech traits being used are often new to crops in that they often do not come from plants (many are from bacteria and viruses), the same basic types of traits often can be found naturally in most plants. These basic traits, like insect and disease resistance, have allowed plants to survive and evolve over time.”

But why would anyone want genetically engineered foods? What are they good for? Well if you’re picturing bananas with wings, think bigger. Not bigger wings, think on a larger scale. Some types of genes inserted are for insect and disease resistance, tolerance to herbicides, higher nutritional value, and a longer shelf life. They are also able to engineer crops so that they are able to grow in harsher environments, for example during droughts or in land with higher salt levels 89. According to the Food and Agriculture Organization of the UN, 20–40% of crops are lost to pests and disease10. All these changes allow farmers to grow more crops and for the end consumer to buy produce with higher nutritional content, which can be a great boon in places where there’s a sore lack of certain nutrients.

Another benefit is the reduction in mycotoxins, harmful compounds produced by fungi living on the crops that cause disease in both animals and humans. The fungus is able to infect crops via wounds inflicted on the plant by insects and other pests. Therefore, plants that are more resistant to pest damage are less likely to contain mycotoxins. It’s been reported that Bt crops, crops producing insecticidal proteins originally produced in the bacteria Bacillus thuringiensis, contain fewer mycotoxins, especially the Bt maize9.

Vitamin A deficiency is a huge problem worldwide. Although the incidence rates are decreasing (it went down from 877 million people in 1990 to only(!) 490 million people in 2019). It can cause developmental issues in children, vision impairments, and immune deficiencies11. An estimated 105,700 children under the age of 5 died from vitamin A deficiency related diseases in 2013. Golden rice is a vitamin A genetically fortified rice first developed in the 90’s and upgraded in 2004 and was the food industry’s way of trying to solve a relatively easily solvable problem. In a recent study, they found that substituting golden rice for regular rice would provide almost all of the daily vitamin A required for preschool children. However, due to the public’s general reluctance and fear of GMOs, there has been much foot dragging around its regulatory approval. In 2021, it was finally approved for use in the Philippines and is currently awaiting approval in Bangladesh. Had it been approved when it was first developed, it could potentially have saved over 2 million people.

In a meta-analysis from 2014, researchers analyzed the financial and environmental benefits of GM crops and found that the use of GM crops has increased crop growth by 22%, reduced the use of chemical pesticides by 37%, and increased profits for farmers by 68%. The increases in crop yields and farmer’s profits is higher in developing countries than in first world countries12, meaning that people in poorer countries where produce is less widely available are more able to get healthier produce year round with GM crops and the farmers are able to make more profit.

So while there are some ecological concerns, most of the concerns people have are taken into consideration during the regulatory processes. Governments are generally not in favor of poisoning their citizens (generally) and it is in their best interest to make sure that foods are safe before being allowed to be consumed. There are huge potential benefits that outweigh the risks in my opinion. Foods can be made healthier (vitamin fortified and with fewer pesticides and mycotoxins) and less allergenic. It can also be hardier and easier to grow in harsher conditions, therefore increasing the amount of food available and decreasing global hunger.

Bibliography

1. GMOs: Pros and Cons, Backed by Evidence. https://www.healthline.com/nutrition/gmo-pros-and-cons. Accessed January 28, 2023.

2. Green Biotech: Methods of Genetic Engineering in Plants. UC Davis Biotechnology Program. https://biotech.ucdavis.edu/blog/green-biotech-methods-genetic-engineering-plants. Accessed May 5, 2023.

3. Menz J, Modrzejewski D, Hartung F, Wilhelm R, Sprink T. Genome edited crops touch the market: A view on the global development and regulatory environment. Front Plant Sci. 2020;11:586027. doi:10.3389/fpls.2020.586027

4. Waltz E. GABA-enriched tomato is first CRISPR-edited food to enter market. Nat Biotechnol. 2022;40(1):9–11. doi:10.1038/d41587–021–00026–2

5. Waltz E. With a free pass, CRISPR-edited plants reach market in record time. Nat Biotechnol. 2018;36(1):6–7. doi:10.1038/nbt0118–6b

6. Tsatsakis AM, Nawaz MA, Tutelyan VA, et al. Impact on environment, ecosystem, diversity and health from culturing and using GMOs as feed and food. Food Chem Toxicol. 2017;107(Pt A):108–121. doi:10.1016/j.fct.2017.06.033

7. Home | CODEXALIMENTARIUS FAO-WHO. https://www.fao.org/fao-who-codexalimentarius/en/. Accessed April 15, 2023.

8. GeneWatch UK — Techniques for Genetically Modifying Plants — A basic guide on how plants are genetically modified. http://www.genewatch.org/sub-532324. Accessed December 17, 2022.

9. de Santis B, Stockhofe N, Wal J-M, et al. Case studies on genetically modified organisms (GMOs): Potential risk scenarios and associated health indicators. Food Chem Toxicol. 2018;117:36–65. doi:10.1016/j.fct.2017.08.033

10. FAO — News Article: Keeping plant pests and diseases at bay: experts focus on global measures. https://www.fao.org/news/story/en/item/280489/icode/. Accessed February 4, 2023.

11. Zhao T, Liu S, Zhang R, et al. Global Burden of Vitamin A Deficiency in 204 Countries and Territories from 1990–2019. Nutrients. 2022;14(5). doi:10.3390/nu14050950

12. Klümper W, Qaim M. A meta-analysis of the impacts of genetically modified crops. PLoS One. 2014;9(11):e111629. doi:10.1371/journal.pone.0111629