PUBLIC PERCEPTIONS OF GENETICALLY ENGINEERED FOOD CROPS
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Many people are passionate about food, and have strong feelings about what they eat and where it comes from. GE protestors frequently use emotional language and images designed to frighten consumers, such as labelling GE foods as “Frankenfoods” and using pictures of children in their advertising. On the other hand, international companies that produce GE seeds and food products have huge advertising budgets to promote, market and advocate the benefits of their products. Both groups have the means and methods to influence public perceptions of genetic engineering and GE foods.
In addition, the scientific realities of crop breeding, agricultural biotechnology, and food safety assessments are often unknown, misunderstood or not heard at all. Let’s examine a few common perceptions about the safety and utility of GE foods, and see what the scientific evidence has to say.
Perception #1: “Genetic engineering puts genes in my food, and I don’t want to eat genes.”
GE crops are plants; plants are living things; all living things contain genes, or discrete sequences of DNA, that orchestrate their growth and development; therefore, we consume genes/DNA all the time and are none the worse for it. This may seem obvious, but a 2003 survey of Americans’ perceptions of GE foods revealed that 40% of the people surveyed believed that genetically engineered tomatoes contained genes, but “ordinary” tomatoes did not. In general, public knowledge about agricultural biotechnology is limited.
Perception #2: Genetic engineering is unnatural.
Food crops have been genetically modified since the beginning of agriculture 10,000 years ago. Early farmers exploited natural genetic variation by saving the seeds of superior plants for the next growing season. This selective breeding strategy changed the genotypes of cultivated plants in parallel to the phenotypes. Crop hybridization and mutation breeding (considered a kind of conventional crop breeding and used in organic agriculture) also change plant genomes. It is incorrect to assume that only GE technology modifies the DNA of crop plants.
The ability of genetic engineering techniques to insert genes from different species into crop plants is considered “unnatural” by some GE opponents. However, all living things share the same genetic code (DNA) and there is no molecular incompatibility between DNA from different species. Here are a few examples. The bread wheat that is grown today is actually hybrid between three different grass species that arose 8,000 years ago. Triticale, a grain used mainly for animal feed, is a hybrid between wheat and rye. Bacteria are used as mini drug factories to synthesize human insulin after insertion of the human insulin gene. Our own genomes carry the DNA remnants of different viral infections during the course of our evolution – yes, viral DNA is stably integrated into the human genome (http://discovermagazine.com/2002/nov/breakvirus).
It is also important to remember that genomes are never stable. Random mutations, big and small, happen all the time. As discussed in the GM/GE backgrounder, the genetic modifications that occur during conventional crop breeding can be big and imprecise, and can have unknown or undesirable consequences. On the other hand, genetic engineering inserts a small number of well-characterized genes with predictable and testable effects.
Perception #3: GE foods can contain new allergens that could harm unsuspecting consumers.
Food allergens are proteins that cause inappropriate immune system reactions in susceptible people. A mild food allergy may result in uncomfortable symptoms like hives, but a severe allergy may be fatal. More than 90 percent of food allergies in North America are caused by the following eight foods: peanuts, tree nuts, milk, eggs, soybeans, wheat, fish and shellfish.
After 16 years of GE crop consumption, there is no scientific evidence that any GE food has ever caused allergic reactions. Health Canada and other regulatory agencies require scientific data that new GE foods do not contain allergens before they are approved for consumption. It is often possible to predict if a protein could be an allergen by comparing its amino acid sequence and structure to known protein allergens. Proteins can also be directly tested in the lab to determine if they are potential allergens.
Some genetic engineering research is actually trying to remove or reduce the allergens in the “top eight” allergenic foods listed above. Removing an allergen completely can be impractical if the protein is important for the plant’s growth or makes up a large proportion of the food. However, changing the structure of an allergen so that it doesn’t provoke a severe immune reaction seems to be feasible. This would be enormously helpful to people who are allergic to common foods that are hard to avoid like milk, soybeans and wheat.
Perception #4: GE foods can spread antibiotic resistance.
Antibiotic resistance is a serious and growing concern. When antibiotics (drugs that kill bacteria) are misused or overused, then the target bacteria evolve resistance. This severely compromises our ability to use antibiotics to fight bacterial infections. There are several contributing factors to the spread of antibiotic resistance, but GE crops are not one of them.
The supposed connection between GE and antibiotic resistance lies in the inclusion of antibiotic genes as selectable markers in the plasmids used to transform crop plants (Figure 6, GM and GE backgrounder). Critics worry that these resistance genes could spread to bacteria in the environment and then be shared with pathogenic bacteria that cause antibiotic-resistant infections. There is also the fear that consuming GE food crops could spread the antibiotic resistance genes to our intestinal bacteria. Here’s a list of reasons why the fear is not supported by science:
1. GE crop developers should use antibiotic resistance genes that are already widespread in the environment.
2. Genes that confer resistance to antibiotics that are powerful or unique in human or veterinary medicine should not be used as selectable markers at all.
3. Researchers have tried for years, under ideal lab conditions, to observe the transfer of antibiotic resistance genes from GE crops to soil bacteria. They have failed, despite the fact that bacteria are relatively good at sharing genes.
4. The probability that resistance genes from GE crop are transferred to intestinal bacteria is extremely small (less than one in a hundred million million). Most DNA does not survive the stomach intact, and successful integration into bacteria is still a rare event, despite their relatively good gene sharing ability.
Even though the odds of GE crops spreading antibiotic resistance are so small, and the resistance markers are already widespread, public pressure has resulted in a lot of research into alternatives. Herbicide resistant genes are sometimes used as selectable markers, but they can be transferred to other plants in the same way as when they are used to create HT-crops. Scientists have developed markers that allow transformed plant cells to use unusual food sources, or cause transformed cells to appear different colours, but these are often inefficient for selection. Lots of research is ongoing into the development of marker-free GE plants, usually through removing a selectable marker after transformed plant cells have been isolated.
Perception #5: Scientists can’t guarantee that GE food is 100% safe, so why risk eating it?
There is no such thing as a 100% safe food. Many people are allergic or intolerant to common foods. Foods can be contaminated with bacteria that make us sick, such as E .coli or Salmonella. Many fruits and vegetable contain natural toxins that can cause adverse effects due to overexposure or improper preparation (http://www.uoguelph.ca/foodsafetynetwork/natural-toxins-fruits-and-vegetables). These risks are relevant whether a food has been genetically modified or not.
GE foods have been tested more than any other food, ever. The food safety assessment done by Health Canada and similar regulatory agencies is rigorous and detailed. It is important to realize that the principle of substantial equivalence, widely used for GE safety assessment, is not a characteristic that is claimed by a company to avoid rigorous testing. It is a novel food characteristic that is determined as a result of testing. Our regulatory system approves GE foods if they are just as safe to consume as their non-GE counterpart. GE food crops have been consumed by hundreds of millions of people since their commercialization in 1996, and there have never been any scientifically credible reports of harm.
Perception #6: GE crops just make life easier for farmers, with herbicide tolerance and insecticide production.
It is true that crops with built-in herbicide resistance (HT-crops) and insecticide production (Bt-crops) make weed and insect control easier for farmers. Even if those were the only benefits of GE crops (they aren’t), a few statistics provided by CropLife Canada (http://www.croplife.ca/just-the-facts) should encourage an appreciation for Canadian agriculture, and technologies that improve the lives of the farmers who feed us.
1. A farmer in 1900 grew enough food for 10 people. Today, an average farmer feeds 120 people.
2. In 1900, people spent 50 cents of every dollar earned on food. Today, we spend 10.6 cents of every dollar.
3. In 2008, Canadian agriculture generated over $70 billion in economic activity.
4. One in eight Canadian jobs is related to agriculture.
Several scientific studies have shown that GE crops actually have a net positive environmental effect when compared to conventional agriculture. In 2010, the National Academy of Sciences in the U.S. published an analysis of the impact of GE crops on farm sustainability. The table below summarizes the key positive findings, along with the unintended consequences
Key Findings of 2010 National Academy of Sciences Report on Farm Sustainability and GE Crops
Positive Environmental Effect
HT-crops are usually resistant to the herbicide glyphosate, which is environmentally safer and less toxic than older herbicides. The widespread cultivation of HT-crops has replaced more toxic herbicides with glyphosate.
Overuse of glyphosate has accelerated the development of glyphosate-resistant weeds. Ten weed species have evolved resistance since HT-crop commercialization in 1996. Herbicide tolerance management plans will be critical to the long-term sustainability of current and future HT-crops.
HT-crops have reduced the amount of tilling. Tilling as a method of weed control decreases soil quality, increases soil erosion, and increases greenhouse gas emissions from diesel-burning tractors.
Bt-corn and Bt-cotton (with built-in insecticide production) have decreased the amount of sprayed pesticides.
Bt-resistance has evolved in a few target insect species, but the agricultural and economic effects have been minor.
From a slightly different perspective, the infiltration of GE plants or flow of HT-genes into neighbouring non-GE fields was identified as a potential economic problem that needs to be studied more. Some markets, such as the European Union, have very low thresholds for the presence of GE traits in the food crops that they import. GE crop presence is also potentially problematic for certified organic farmers.
Globally, the world faces some serious food issues. Millions of people are malnourished or starving in developing countries, and their numbers will only grow since the global population is projected to reach 9 billion by 2050. While GE crops are not the only solution to hunger and malnutrition, they have a lot to offer in terms of improved nutrition of food staples. In poor developing countries, many food staples such as rice, cassava and potatoes are low in protein. Researchers are working on boosting the nutrition of rice and cassava by introducing the gene for a high-quality storage protein. Iron-enriched crops to combat anemia are also in development.
Vitamin A deficiency is a huge problem for people in developing countries, especially children in Africa and Southeast Asia. Each year, vitamin A deficiency causes irreversible blindness in 250,000 – 500,000 children, and half of those children die within one year. Aid agencies run supplementation programs, but increasing the vitamin A content of food staples would be much more efficient. A GE sweet potato, containing four to six times the amount of the vitamin A precursor beta-carotene, was recently shown to be better than regular sweet potatoes at reducing vitamin A deficiency in Ugandan children. Beta-carotene (responsible for the orange colour of vegetables such as carrots, sweet potatoes and peppers) is easily converted to vitamin A in the body. Rice is a staple food for millions of people in poor countries, but rice grains don’t contain any vitamin A at all. Vitamin A-enriched rice, dubbed Golden Rice due to its pale orange colour, is genetically engineered to produce beta-carotene. Even though the levels of beta-carotene in Golden Rice are much lower than in sweet potatoes, it is enough to mitigate the terrible effects of vitamin A deficiency. After years of political and regulatory obstacles, Golden Rice is moving closer to approval. All you ever wanted to know about the science and politics of Golden Rice can be found at http://www.goldenrice.org/index.php.
…Now a Final Thought
It should be clear from all the discussion of crop breeding, agricultural biotechnology, safety assessments and government regulation that genetic engineering of food crops is a valuable and safe technology. That is not to say that it is perfect. In particular, the spread of herbicide tolerance genes to weeds needs careful and ongoing management. However, GE crops have several environmental benefits, are safe to eat, and have enormous potential for improving the lives of people in developing countries. Even considering only herbicide tolerant and insect resistant crops (the most-grown GE crops worldwide), developing countries account for almost half of the global GE crop area, and have a higher GE crop adoption rate than developed countries. Farmers in developed countries are clearly not the only beneficiaries of GE crops.
While organic agriculture practices are lauded for their sustainability, GE crops are an indispensable part of our current and future food production system. It is unlikely that organic agriculture can produce enough food for the global population. Some scientists believe that a synthesis of organic and GE is our best path to sustainable agriculture that can feed the world. For an excellent article about this perspective: http://www.popsci.com/science/article/2011-01/second-green-revolution-alliance-organic-farmers-and-genetic-engineers
“Are Foods Derived from GM Crops Safe?”: http://isaaa.org/resources/publications/pocketk/3/default.asp
Understanding risk and safety assessment for genetically modified plants:
McHughen A and Wager R. (2010) Popular misconceptions: agricultural biotechnology. New Biotechnology 27: 724-728.
2003 Survey of Public Perceptions of GE Food and Knowledge of Agricultural Biotech:
Genetic History of Bread Wheat:
GE foods and allergens: http://agribiotech.info/details/McHughen-Allergy%20Mar%208%20-%2003.pdf
GE foods and antibiotic resistance: http://agribiotech.info/details/Chassy-antibioticMarch%208%20-%2003.pdf
Selectable Marker-Free GE Plants:
National Academy of Sciences Report, “Impact of Genetically Engineered Crops on Farm Sustainability in the United States”: http://www.nap.edu/openbook.php?record_id=12804&page=1
GE Crops to Enhance Nutrition:
Global Status of Commercialized GE Crops in 2011:
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