Safety Concerns and Genetic Engineering in Agriculture
Federal agencies are considering various regulations to protect the public from environmental and health problems that might arise from the release of genetically engineered organisms. Concern has been expressed because several agricultural practices, such as the widespread use of DDT in past decades, (1), have caused serious problems that were unintended and unexpected. Also, movement of weeds and insect pests into new environments has created problems that have become difficult to control. Examples include kudzu, hydrilla, the gypsy moth, and the Japanese beetle. Because of these experiences, it is necessary to consider the potential effects of releasing organisms containing genes from related and unrelated genera. This article will focus on the safety issues involved in using genetically engineered plants and microorganisms (bacteria and fungi) to benefit agriculture. Other applications to which the same principles should hold with respect to safety issues include the use of genetically engineered organisms for mining, waste treatment, and detoxifying chemical spills.
The economic and environmental benefits expected to accrue from agricultural use of recombinant organisms are great (2) and should be considered in relation to the potential risks. By splicing foreign genes into plant chromosomes it may be possible to create plants resistant to a wide array of pests. The hope and expectation is that they will lead to decreased use of chemical fungicides and insecticides, many of which are toxic to man. Recombinant DNA techniques may be used to develop plants that utilize fertilizers more efficiently, thereby minimizing fertilizer runoff into streams and lakes. In many crop species a relatively narrow base of germplasm is being used to develop varieties. There is concern that this has created genetic vulnerability to disease (3). Genetic engineering can be used to introduce new genes and thereby increase genetic variability for the future. The time it takes to develop new plant varieties should be greatly decreased by this new technology.
Genetically engineered bacteria and fungi also have potential value. For example, Rhizobium strains isolated from many locations around the world are being applied to soils in large numbers so that legumes can produce high yields without needing expensive nitrogenous fertilizers. Several approaches are being considered to increase legume yields with genetically engineered Rhizobium (4). Other microbes, such as mycorrhizae, Pseudomonas, and Frankia (5), are also promising candidates for use in agriculture, and there is a good chance that the value of these organisms can be increased through recombinant DNA technology as well as traditional mutation and recombination techniques. As in traditional agriculture, the value of the new plants and microbes can be assessed only after they have been tested under a variety of field conditions. This article will discuss ways to predict the safety level of an organism that has received several foreign genes.
Of particular concern in the introduction of new organisms is the potential to self-perpetuate and spread. For the purpose of this discussion, however, a problem plant that gets no farther than the next field is not defined...
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