Экология/ 3.Радиационная безопасность и социально-экологические проблемы

Tovtin E. I.

Vlasova I. A.

Donetsk state university of economics and trade

after Michael Tugan-Baranovsky, Ukraine

Genetic Modification of Food

Genetic Modification of Food, the alteration of the genome of plants grown for food in order to produce crops with specific advantages such as improved yield or resistance to herbicides and insect pests. We have been modifying the genetic material of crops since the dawn of agriculture, by selection of seeds from better yielding plants, then later by deliberate cross-pollination to select desirable characteristics. The difference with modern genetic modification (recombinant DNA technology) is that we can now introduce specific genes, for a defined purpose, not only from another strain of the same plant, but from a totally different species (see Genetic Engineering); genetically modified (GM) organisms are sometimes known as transgenic. The gene donor may be another plant, an animal, or a micro-organism. This raises potential problems of both the safety of consuming food from the modified crop, and possible environmental hazards. There are also ethical questions to be considered and wider political and economic issues related to the control of modified crops and seeds by powerful corporations, and their control over small farmers, particularly in developing countries. As more information on the function of plant genes becomes available, so more precise genetic modification to introduce desirable characteristics will be possible. The complete genome of Arabidopsis thaliana (thale cress) was elucidated in December 2000, providing a model for dicotyledonous plants (see Dicots). Rice is the model for monocotyledonous plants (see Monocots); it has the smallest genome of the major grain crops, and provides the dietary staple of half the world's population. The rice genome sequence was completed in 2001. Concerns have been raised about the business ethics that may drive the application of these powerful technologies, especially since the products concerned are often staple foods. Many people are unhappy about an herbicide-resistant crop being developed and marketed by a company that also manufactures the herbicide, raising the suspicion that the main beneficiary will be the company concerned rather than the consumer. Equally, many people are extremely unhappy about the development of the so-called “terminator gene”, which causes seeds from genetically modified crops to be sterile. This would force farmers to buy fresh seed from the supplier each year, instead of keeping a proportion of the harvest for the next season’s seed. The major plant biotechnology companies have (at least at present) undertaken not to pursue further development of terminator genes, although a number have been planted. Once the gene for the desired characteristic has been identified and isolated, it has to be introduced into the plant that is to be modified, together with a control (promoter) region that will ensure the new gene is expressed in the plant. These techniques for introduction of DNA into cells are far from perfect, and there has to be a simple way of detecting those cells in which the gene transplant has been successful, so that these can be grown up, and those in which the procedure has failed can be discarded. All that is needed is to culture the plant tissue in the presence of the herbicide; only cells in which the gene has been introduced successfully will grow. In other cases a marker gene is introduced together with the desired gene. This is commonly a gene conferring antibiotic resistance, so that growth in the presence of the antibiotic will eliminate those cells in which the procedure has failed. Increasingly, other marker genes, such as those conferring the ability to grow on unusual sugars, are being used. In this case, selection of those cells in which the gene has been introduced successfully is by culturing the cells on a medium providing only the unusual sugar, so as to eliminate those that cannot use this substrate. United Nations expert committees and national and international authorities have proposed clear guidelines for testing for possible hazards, while noting the considerable potential advantages in terms of increasing world food supplies to feed the ever-growing population of the world. In response to consumers’ concerns about genetically modified crops, a number of major food retailers have announced that they will not include any in their own-brand products. In advance of legal requirement many instituted a policy of voluntary labelling of foods containing ingredients from genetically modified organisms, so as to permit consumers to make a conscious choice. EU legislation introduced in 2003 requires that all foods made from or containing more than 0.9 per cent GM material must be so labelled; this includes highly refined oils from GM plants, even though they contain neither DNA nor protein. Foods made using (as opposed to containing) GM organisms do not have to be labelled as such - this includes, for example, cheese made using “vegetarian rennet”, an enzyme derived from GM bacteria that does not remain in the cheese. There remains the problem that GM and conventional crops may be mixed before coming to market, so that it may not be possible to ensure that foods are indeed produced only from conventional crops.With wind-pollinated plants, such as maize, it is generally assumed that a relatively small crop-free zone will provide protection against transfer to other crops, since such crops generally have to be grown relatively close together to achieve maximum pollination. However, this does not exclude the possibility that pollen may travel a considerable distance in the wind, and so could spread far beyond its intended target area. The risk of cross-pollination is higher for insect-pollinated crops. Insects may travel a considerable distance during a day, collecting nectar and pollen; pollen from genetically modified crops has been found in beehives several kilometres from the nearest source. Before the widespread introduction of genetically modified crops there is an obvious need for a significant number of carefully controlled trials, in isolated areas that can be monitored closely, in order to determine whether or not these risks pose any real environmental hazards. While there have already been a considerable number of such trials, there is not yet any clear evidence of safety or otherwise. In the UK and elsewhere there have been some incidents of environmentalist protestors destroying fields of trial crops. There has been criticism also of agricultural biotechnology companies, some of which have admitted to ignoring or breaking the regulations governing trials, for example by not allowing an adequate buffer zone between GM trial crops and conventional crops. There has been at least one occasion when GM seeds were, apparently accidentally, mixed with conventional seeds and sold for commercial cultivation. Despite the widespread cultivation of GM crops in the US and elsewhere, governments in Europe and Africa are cautious about permitting their introduction before the evaluation of stringently controlled trials