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转基因食物是否安全
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转基因食物是否安全
这已不是什么新话题了，
右侧为美国普林斯顿大学分子生物化学系的文章。可能更接近实际情况。
右侧中下部分的英文的中文红字！ （政府的立场受资本左右，学者也多数是。但后者可能有例外。）
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INTRODUCTION The use of biotechnology to genetically modify food is a very controversial subject. There are many pros and cons associated with this practice, and each side makes very strong points. It is important that people have an understanding which food is and has been genetically altered, and of the risks and benefits associated with this ability. Genetically changing food is viewed in a manner similar to cloning, but unlike cloning, the practice of genetically altering food will have a direct impact on everyone, which is why education and awareness is so important. Many people are not aware of this topic, and most have no idea how prevalent genetically altered food is already. Biotech companies such as Monsanto invest considerable amounts of money in this practice. Many genetically modified foods have already been approved. It is estimated that as many as 60-70% of packaged foods already contain ingredients from genetically-altered organisms. Essentially every grain, vegetable, fruit, and legume have already been genetically altered in the laboratory, along with many organisms that are used either directly as food or in production. Some examples of genetically modified foods are modified yeasts (used in bread, food supplements, beer, and many other processed foods), several herbicide and pesticide resistant crops (such as maize, corn, potatoes, etc…), and modified food additives and enzymes (such as amylase, catalase, and lactase, and are all used in many products) just to name a few. Genetically modifying food can have many possible beneficial and negative effects. These effects will be spread throughout the human population and will impact every person.
Possible Benefits of Genetically
Modified Foods The ability to genetically alter foods has the potential to be a very potent and useful tool in our arsenal to combat the world’s problems. There are many possible benefits of genetically altering foods ranging from enhancing disease and pest resistance to increasing the nutritional value of food. Production improvements are one possible benefit. Growth rates and yields will be increased, which will allow more food to be produced from the same amount of land. Another benefit is enhancing resistance to pests, weeds, and diseases. Introducing genetics that increase resistance will allow more crops to be grown, and potentially less chemical herbicides and pesticides to be used. Genetic engineering may also allow crops to be grown in a wider range of environments, especially less fertile and harsher areas. This would obviously increase the amount of land open for agriculture. Another benefit is that food would be cheaper, and have a longer shelf life. All of these benefits will increase the efficiency of agriculture, lower the costs of foods, increase the nutritional and medicinal value of food, and increase the quantity able to be produced. Clearly, this would be of global importance in a time of incredible population growth and overcrowding. Some other benefits are that engineering could improve physical aspects of food, such as taste, texture, and nutritional quality. Certain amino acids could be increased in food items, making them more nutritious and possibly lowering the mount of food intake actually needed per person. In effect this would increase food supplies. Another possible benefit is that crops and animals could be used to produce novel substances for other uses. One example of this is genetically engineering cows to produce milk that contains antibiotics, vaccines, or other medicinal qualities. Foods could be used to vaccinate entire populations, and used to increase the immune function of people, making them healthier. For example, there have been plans to insert a rabies gene into crops which are fed on by wild animals. Theoretically, this would immunize wild populations against rabies, and that would lower the incidence among humans. There are a number of substances that can be obtained through genetic modification, such as certain detergents (from fatty acids), substitute fuels, and petrochemicals, to name a few.
There are many food engineering projects underway at present. These include development of resistant crops (maize, soybean, cotton, rapeseed, potato, tobacco, rice and tomato) and projects to speed up traditional breeding and development of plants, to create healthier, more digestible and nutritious foods, and create hardier crops. Also research in producing organisms with medicinal value is progressing. Projects on implanting a diabetes vaccine into tobacco and potatoes, and potatoes that provide immunity to cholera, both show great promise. Also promising are studies on genetically modified biodegradable plastics grown in plants, which could potentially replace plastics generated from fossil fuels in the near future. Genetically modified plants are also being used to restore heavily polluted lands through phytoremediation, which is a process by which plants remove toxic compounds from the earth. Clearly,
there are many possible benefits that could be derived from genetically
modifying foods. It is an especially valuable asset in today’s world when
starvation, overcrowding, and disease are so prevalent. The possible benefits
are nearly endless and can potentially be applied to nearly every aspect of
human life. Some of the Ethical Problems with
Genetically Modified Foods There are also other more general ethical problems. Many people are concerned that one of the genetically modified foods will never reach the hungry third world nations who may need them most. The fear is that genetically enhanced foods are not aimed at the third world, but at the profitable supermarkets, and that the benefits will never be felt in impoverished countries. Another
concern is that modified foods (especially transgenic foods) can cause ethical
objections in certain religious and ethnic groups. If such objections
prohibited consumption of genetically modified foods, it might put these groups
at a significant disadvantage. Other Potential Problems with
Genetically Modified Foods The complex ethical concerns are only one type of potential problem with genetically modified foods. There are many others. Many problems could result from genetically altering food producing organisms. It is very difficult to predict the results of genetic engineering. There are often completely unforeseen consequences to such endeavors, which may only be discovered after the problem has occurred. A result of uncontrolled integration of new genetic material into a genome can be completely unanticipated secondary and pleiotropic effects that can have a strong impact on the biology of the host organism. Some potentially dangerous results of the introduction of genetic material include the production of completely new and possibly toxic products, a species with new allergenic properties, and decrease in nutritional value. Studies have shown that the risk of new and unprecedented allergies is much higher in transgenic plants than in ungenetically modified plants. In addition to unanticipated effects, genetic ‘pollution’ is another problem. Short unwanted genes that may have deleterious effects can hitch a ride with the target genes and be integrated along with the desired genetic material, which can compound potential problems. If these deleterious genes are transmitted by any mechanism to other organisms or wild populations, they can have drastic effects on the fitness of various species and ecosystem stability, which in turn will effect the environment and human health. There are several examples of such effects. For example, when modified to have a three-fold increase in a certain enzyme, yeast S. cerevisiae, which is used in food production, experienced a 40-fold increase in the toxic substance methylglyoxal, which may cause damage to the DNA of a consumer. Another organism, Klebsiella planticola, was altered to produce ethanol out of plant residues. However, when released into the field, the organism caused several ecological problems such as outcompeting other natural organisms (resulting in lower biodiversity and lower productivity of the soil), persistance in the soil, and causing the death of plants growing in the soil. Genetically engineered tryptophan, a food suplement modified to speed up production, caused eosinophilia-myalgia syndrome, which resulted in 37 deaths and 1500 permanently disabled people. All of these results were completely unanticipated. 警告 Horizontal gene transfer is another potentially big problem. Certain genetically engineered organisms (especially microorganisms and plants) have the potential to readily pass genetic material between each other both horizontally and vertically. This means that such organisms could potentially pass modified genes to other unmodified organisms, which would alter those organisms and can have serious results. It was recently demonstrated that a genetic parasite occurring in yeast suddenly jumped into many unrelated species of higher plants. As of 1995, this parasite was thought to be confined to yeast, but in a recent study, it was shown that it has spread to at least 48 new species of plants. This is a mechanism that is especially a problem in terms of the transfer of antibiotic, pest, and disease resistance genes, and could result in the formation of super-weeds or diseases. A plant could be modified to be resistant to pests or certain diseases, but as a result of hybridization (a common occurrence in the plant and animal world), this trait could be passed to other plants, which could result in a super-weed that cannot be controlled by traditional methods. Studies have also shown that there is a possibility that such horizontal transfer can occur in the intestinal tract of animals (and possibly humans), which may have serious health effects, especially in terms of antibiotic resistance. （横向的基因传递是一个潜大的大问题。特定的基因工程有机体，特别是微生物和植物，具有潜在的在水平和垂直方向进行传递遗传物质的能力。这意味着这些转基因食物可能会将改造的基因传给另处未经改造的有机体，从而改变其基因，这可能造成严重的后果。近期的实验证实：酵母中的基因“寄生虫”突然跳到不相关的高等级植物物种上。这个机制特别见于抗生素与病源微生物之间的传递上（耐药性），和抗病物种的产生，和超级害虫和病种。 一个物种可以改造成抗病、抗虫，但作为一个杂交的结果，这些特性可传递给别的植物，其结果往往不能人为控制。如果传给人，可能会有严重的后果，如耐药菌种的出现。） One of the big problems is that once such modified crops or microorganisms either are released or escape into the wild, they can never be fully recalled or contained. The introduction of modified organisms into the environment can have severe and unforeseeable consequences. Modified crops can hybridize with other unwanted plants, transferring beneficial genes to undesirable organisms. The genes of such modified organisms are then in the gene pool and can be further passed on to other organisms, and will persist for a long time in nature. For example, genetically engineered salmon that have deformities and biological problems escaped in Canada, and are interbreeding with natural populations, and the effects on salmon populations could be enormous and fisheries could be severely damaged. These types of occurrences could cause long lasting and severe ecological problems that, as is often the case, eventually have strong impact on human health. Also, the fact that engineered crops are usually designed to have higher resistance to chemicals seems to actually encourage increased use of those chemicals to control pests. Soybeans and canola oil in stores are from plants that have been modified to be resistant to herbicides, which allows more chemicals to be used on them with out killing them. This causes many problems such as reduced soil fertility, toxicity in plants and animals, and leads to increased contamination of the food, soil, and water. Increased incidence of chemicals in the environment can lead to human health threats such as immune system problems, reproductive problems, and increased fetal damage. ，
改造的基因，如果逃逸到野外，失去人的控制，则后果无法预料。 Summary There are many potential problems with genetically modifying food. Imprecise technology, unforeseen side effects, creation of new toxins and allergens, possible decreased nutritional value, antibiotic resistant organisms, increased use of chemicals in crops, genetic pollution, and widespread ecological damage are some of the big problems that may be associated with this practice. However, the potential benefits are mindboggling. Genetic engineering has the potential to deal with, at least to some extent, most problems facing mankind today. Part of the problem is that this technology is new and relatively untested. Researchers seem to have dove right into this endeavor often without fully considering the consequenes, as is apparent from several of the health problems that have already arisen such as the tryptophan disaster, increasing allergies, and resistance in pests.. We simply do not have enough experience and knowledge to fully evaluate either the beneficial or deleterious potential of this practice. People can philosophize and ponder the potential results, but we simply do not know enough to go either way. However, the threats are significant enough that caution is demanded, and absolutely every precaution must be taken if research and application are to be continued.
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