Genetically Modified Foods: Worth the Risk?
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Genetically Modified Foods: Worth the Risk?






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Genetically Modified Foods: Worth the Risk? Genetically Modified Foods: Worth the Risk? Presentation Transcript

  • Genetically Modified Foods: Worth the Risk? By Kassandra Thomson BME 333T April 22, 2005
  • Beginning of GMOs
    • In 1976, the company called Monsanto introduced its signature product, Roundup®, an herbicide widely used in farming. By 1981, the company’s research focus had shifted to biotechnology after they established their own molecular biology division. Within two years, Monsanto scientists had come up with the first genetically modified plant: tobacco with a gene coding for resistance to the antibiotic kanamycin. This “kan-resistance” simplifies the task of separating the cells containing new genes from the cells that did not take up the new genes. This is accomplished by growing a cell culture in the presence of kanamycin. The cells with the added genes will grow, while those without the antibiotic resistance will die. Growing and processing techniques that employ this method are faster and easier, and can perhaps lessen the cost of developing GMOs.
  • First in the Field The first field test of a genetically modified organism occurred in 1986. A product called Frostban was sprayed on a field of strawberries in California. It contained genetically altered bacteria that were designed to stop the growth of other bacteria that enhance ice formation. This would allow the plants sprayed with Frostban to survive in temperatures much lower than they could without the spray. Because of the open-air testing of this new GM product, there was a large protest by local residents on the day of the spraying. They ended up forming The Strawberry Liberation Front, a protest group opposed to genetic modification of food. It was the first group of its kind in the United States. They were reported to be responsible for the uprooting of a large number of the strawberries that were to be sprayed the night before the Frostban trial.
    • http:// _ beginnings/ gm_history.shtml
    • http://
  • Moving Forward
    • http://
    However, there was much more public resistance to the use of genetically modified foods in other countries. Most of Europe was adamantly opposed to the introduction of GM products into their food supply, and even developed laws to ban them in later years. Organizations such as Friends of the Earth and Greenpeace staged numerous acts of opposition. There were protests in countries that were growing GM crops experimentally, including Ukraine, India, and New Zealand. This widespread conflict was touted as “one of the greatest revolts against a new technology in history.” Public interest in opposition to genetically altered foods did not last very long, at least not in the United States. The Food and Drug Administration declared GM foods to be “not inherently dangerous” in 1993. As a result, many Americans began to accept the idea of incorporating genetically altered organisms into their food supply. This opened the door for American companies to market GM seeds to farmers.
  • Why bother? There are several advantages that genetically modified crops could offer us. Foods can be modified to enhance their flavor, making the end product more enjoyable for consumers. Overall yields could be increased when GM crops with pesticide or cold weather resistance are grown, since a smaller percentage of the crop would be lost to insect or frost damage. Supporters of GMOs argue this could be a solution to the world hunger dilemma. However, opposing parties claim the world hunger problem is one of distribution, not supply, so the increased crop production resulting from the use of GM foods would not be very helpful. Nutritional benefits of GM foods include the possibility of creating foods that make higher amounts of certain vitamins or other molecules that are essential to our diets. The classic example of this is the development of Golden Rice, modified to enhance the production of Vitamin A in the body. The possibility of incorporating vaccines into GM foods is being explored. Growing genetically altered crops could reduce the amount of pesticides, herbicides, and fertilizers used, which would be of great benefit to our environment.
    • http:// / 2000abstracts%5Cgmfoods.htm
  • If they’re so wonderful, what’s the problem?
    Although there are many advantages of using GM foods, there are also a substantial number of risks and unknown outcomes involved. The long term effects in humans who consume these genetically altered foods have yet to be discovered. So far no adverse effects have been found, but the technology is still relatively new, and who knows what may happen in the future. The possibility of the modified genes spreading to other organisms poses another problem. If the pesticide-resistant gene of a crop were to cross over into local weed populations, then the weeds would no longer be killed by the pesticide. This basically renders the genetic alterations in the crop useless. Other potential drawbacks include the unknown allergic responses people may have to the genetically altered foods. Food allergies can cause serious health problems in many people and in some cases, they can lead to death if not treated promptly. Perhaps just as alarming is the foreseeable loss of biodiversity, leading to the development of monocultures. Through natural selection, the less “successful” plants will not survive, causing the death of those organisms that live off of them. The resulting single crops become more susceptible to the spread of diseases, since there is only one genetic version of the plant growing.
  • Some Examples of GMOs
    • Bt corn – US, 1996
    • Roundup ® Ready Soybeans – US, 1996
    • Flavr Savr® tomatoes – US, 1994
    • “ Golden Rice” – Switzerland, 1999
  • Bt Corn: What is it?
    • The transgenic corn hybrid Bt corn was first made available to growers in the U.S. in 1996 by Ciba Seeds and Mycogen Seeds. This plant was developed to eliminate the threat of the European corn borer (Ostrinia nubilalis) to corn crops. The corn borer is a prominent pest that is responsible for most of the damage caused to corn crops in the U.S. corn belt and mid-Atlantic states, as well as Canada. The genetically modified corn seed produces an insecticide protein that comes from the bacterium Bacillus thuringiensis (Bt). This bacterium is naturally found in soil worldwide. The crystalline proteins it produces have a high specificity for certain groups of insects. Once digested, enzymes within the insects’ stomach activate the toxic form of the protein, killing the pest in a short period of time. The protein is particularly toxic to the larvae of the corn borer. This highly effective method of pest control has been utilized in pesticide sprays that contain Bt for over thirty years. However, the performance of this form of pest control is subject to alteration by UV radiation, heat, and inadequate coverage of a field, and is less effective against insects in later stages of growth.
  • Life Cycle of European Corn Borer
    • http:// /
    New Eggs 1 st Generation Larvae 2 nd Generation Larvae 5 th Instar Larvae Adult Target stages of Bt toxin
  • Damage Report
    If this doesn’t kill the plant, the increased susceptibility to disease might. Corn borer damage increases the plant’s vulnerability to fungi and bacteria. There is a possibility that infected corn seeds could get fed to livestock, which might put these disease-causing organisms into our food supply. The European corn borer is responsible for the largest amount of corn crop damage in the United States and Canada. Monetary losses due to damage and control of the corn borer add up to more than $1 billion yearly. The larvae burrow through the corn stalks and ears, and eat through the leaves of the plant. Stalk lodging is often a consequence of corn borer infestation.
    Stalk Lodging: Damage that occurs when the stalk of the corn plant breaks below the ear of corn, leading to decreases in the yield of a harvest, an increase in the amount of time it takes to harvest a crop, and an increase in the required drying time. Grain quality may also be negatively affected.
  • Danger Will Robinson? Humans and animals cannot be harmed by the Bt protein, since it is specific for receptors found only in the gut of certain insect species. Bt corn can safely be fed to livestock and poultry, for this same reason. An allergic response to Bt is extremely unlikely, since the protein is easily digested in the stomach and is degraded by high temperatures. In addition, there is no worry of causing any resistance to antibiotics, since the genetically modified corn does not have antibiotic-resistance genes. Groundwater contamination will not be an issue, since the Bt protein will bind to soil particles before it reaches the underground water supply. Here it will either be destroyed by acids in the soil, or by heat and radiation from the sun. There are, however, some potential problems with these transgenic crops. The possibility of the corn borer building up a resistance to the Bt protein has been investigated. No pest resistance has been observed in clinical trials, but testing periods have only lasted a few years thus far. It has been discovered that Lepidopteran insects such as the Monarch butterfly are susceptible to the Bt protein if pollen from the transgenic corn finds its way onto milkweed plants (usually found growing near corn fields). Preliminary research indicates the caterpillars that feed on these Bt-pollen-dusted milkweed plants either die or have stunted growth compared to those not exposed to the pollen. More research is needed to determine how Monarchs and other non-target species are affected.
    • http://
  • Roundup ® Ready Soybeans
    • http:// / content/media/pubs/ rrsoybean_ffsafety.pdf
    Another example of a genetically modified plant is the Roundup® Ready soybean, which was developed by the Monsanto company in 1996. These plants have been genetically altered to be resistant to the herbicide Roundup®, another product of the company that is a primary source of revenue. This resistance would allow fields to be sprayed with large doses of the weed killer without causing damage to the soybeans being grown. The sale of these soybeans would bring the company enormous profits as farmers who plant the seeds switch to the herbicide Roundup®.
  • Environmental Effects
    • http:// / biotechnology_archive/page.cfm?pageID =361 The use of Roundup® Ready products gives farmers an easier way to control weed growth, since most herbicides tend to damage soybean plants. Time is saved by being able to spray entire fields to rid them of weeds, instead of having to spray more selectively. In addition, only one application of one herbicide is needed at a time. However, many do not believe the benefits of the Roundup® resistance crops outweigh the disadvantages. Atrazine is currently one of the most widely used herbicides in the United States. However, it contains chemicals that are detrimental to both the environment and to our health. Monsanto advertises its product Roundup®, which contains the slightly less toxic compound glyphosate, as an alternative to atrazine. Those opposed to the Roundup® Ready soybeans claim that a switch from one herbicide to another is not a benefit at all, arguing that glyphosate is still highly toxic to plants and fish. It is very unlikely that an attempt will be made to develop a genetically modified plant that would decrease the need for a company’s herbicide products. For this reason, many believe our agriculture will always be dependent upon heavy usage of chemicals.
  • Flavr Savr ® Tomatoes
    • http:// =Show Prod&data =FLAVR+SAVR Calgene, Inc. developed a genetically modified tomato that was approved for market by the FDA in 1994. The Flavr Savr® tomato has an extra copy of a gene that codes for the enzyme polygalacturonase (PG), except it has been inserted in the antisense orientation (essentially, in backwards order). The PG enzyme is responsible for the breakdown of pectin within the cell walls of plants, which causes fruits to become soft as they ripen. By incorporating the antisense PG gene, the expression of PG in ripening fruit is decreased. The result of this genetic alteration is tougher skin. Traditional shipping methods require tomatoes be picked before they are ripe, so that they may be shipped without fear of damage. Once they have reached their destination, they are sprayed with ethylene, a natural ripening agent. With more durable skin and longer ripening times, Flavr Savr® tomatoes can be allowed to ripen on the vine, yielding a much better tasting product. A gene for resistance to the antibiotic kanamycin is also included in the hybrid for reasons discussed earlier.
  • The Controversy
    • Several safety questions were brought up with regards to the Flavr Savr® tomato during its development and introduction to the food supply. FDA testing confirmed the protein products of the inserted genes did not resemble any known food allergens, were produced in low quantities, and were quickly digested in the stomach. Thus, no foreseeable health risks were associated with the consumption of the GM tomatoes. The nutritional value of the Flavr Savr® was comparable to that of natural tomatoes, with unchanged production of lycopene and beta-carotene. Flavr Savr® tomatoes had a longer shelf-life, enhanced flavor, and a greater resistance to fungal disease than natural tomatoes. The Flavr Savr® tomato was taken off the market in 1997, after Monsanto bought up Calgene and decided not to focus on the production of this product. Reasons for this include supply problems, inconsistent quality of products, and poor sales of the hybrid.
  • “ Golden Rice”
    • http://
    The so-called “Golden Rice” is a genetically modified crop that was developed by Swiss and German scientists in 1999. This breed of rice was engineered to produce higher levels of beta-carotene, the precursor of Vitamin A in the human body. Increased levels of this substance give the rice its characteristic “golden” color. Millions of people around the world suffer from vitamin A deficiency (VAD), with the majority living in developing countries. Advanced VAD can lead to blindness, while minor cases of VAD cause the patient to be more susceptible to disease by weakening their immune system. Pregnant women and children are especially vulnerable. VAD is responsible for blindness in about 350,000 children and over a million deaths each year. Upon its introduction, Golden Rice was thought to be a miracle cure for VAD. However, several drawbacks have been discovered that may cast a shadow on these hopes.
  • Miracle or Mirage?
    • http:// /content/full/ 125/3/1157 Studies show that although the levels of beta-carotene are increased in Golden Rice, they are insufficient to provide any sort of cure for VAD. At the current level of 2.0 μg beta-carotene/g of rice, a woman would need to consume over 15 lbs. of this rice a day to get her required Vitamin A dosage, and a small child would have to eat almost the same amount. If they were to eat a normal amount of this rice every day, it would provide them with less than 10% of their required Vitamin A intake. Pregnant women would receive an even smaller percentage of this amount. Genetically altered rice seeds are currently being provided to poor subsistence farmers in developing countries free of charge and restrictions. Many people see this as an enormous problem, since the spread of the altered genes will not be under any type of regulation in these countries. Opponents to GMOs consider the distribution of Golden Rice to these countries as a “Trojan horse” that will pave the way for future GM products to make it to market. Their main strategy to undermine the success of Golden Rice has been to chip away at consumer acceptance.
  • Conclusions Advantages Disadvantages Genetically modified crops have the potential for increased crop yields due to decreased damage by pests and herbicides, and could provide an additional food source for malnourished populations around the world. Enhanced nutrition and flavor of GM foods provide benefits for all consumers. Genetically altered foods hold many possibilities for the future. For example, foods containing vaccines are being developed. Applications of this that are currently under study include genes that will produce HIV-transmission blockers, antibodies for rabies, and antibodies for Hepatitis B. There are several drawbacks to using GM foods, most of which are due to the unknown effects they may have on human health and the environment. There is still considerable doubt that there will be no long-term effects of consuming GM foods. One of the gravest concerns is the potential allergenicity of these products. The reason for the immune system’s violent allergic response to otherwise harmless substances is not entirely understood. The introduction of new organisms (ie, GM foods) to our population could have devastating results if an allergenic molecule is produced by the product. In addition, the development of a “superior” breed of an organism could lead to a loss of biodiversity, which could throw off balance the entire world’s ecosystem.
  • It remains to be seen how well genetically modified products will become integrated into our society. The main deciding factors are the safety of the product for both humans and the environment, the cost of development, and the acceptance of the consumer.
  • Additional References