With every emerging technology are associated potential risks. The relevant question is not whether there are risks but whether the perceived risks can be effectively managed. If the perceived risk is inevitable, is it a new one? If it is, does it pose more harm than the current risks being faced? Below are some of the main issues of concern about the introduction of GM crops.

Issue:
The possibility that transgenic crops with antibiotic resistance marker (ARM) gene may generate antibiotic resistance in microbes, especially in the gut microflora of humans.

Response:
The greater and real problem regarding antibiotic resistance is the indiscriminate use of antibiotics in humans. With GM crops, development of antibiotic resistance is only a far and very unlikely possibility.

In GM foods where the ARM gene is used, the possibility that the plant genes will be integrated into bacteria’s genetic material is extremely remote. This is because bacterial genes are very dissimilar to plant genes. Plant genes contain introns while bacterial genes don’t. (Introns are nucleotide sequences that do not code for amino acids). The preferred genetic codon usage in plants is different from that of bacteria. (Codons are triplets of nucleotides that code for amino acids). Furthermore, plants and bacteria use different kinds of regulatory sequences (promoters and teminators). This immense dissimilarity in the genetic level of plants and bacteria makes it virtually impossible for the ARM gene to be transferred. Besides, it is almost inconceivable that a large chunk of DNA could survive in the extensive hydrolytic breakdown during digestion in the human gut.

Moreover, as a substitute to ARM, there is now a wide array of selectable marker genes that technology developers can use or are already using. New GM products no longer use the ARM technology.

Issue:
Danger of unintentionally introducing allergens and other antinutrient factors

Response:
It is important to keep in mind that conventional foods like egg, peanuts, bread and coffee have certain levels of allergens, toxins or antinutrients. A GM peanut with an insect-resistance trait still contains the allergens that a non-GM peanut normally has because only the insect-resistance gene is added. A naturally allergenic food will remain allergenic in its GM form – unless it has been modified so that the genes encoding for the allergens are removed.

The level of risk of allergen, toxin or anti-nutrient production in GM foods is evaluated by standard toxicological methods as included in current risk assessment paradigms. To date, there has been no documented case where a human allergen was introduced into a commercially released food component by genetic engineering.

Issue:
Likelihood of transgenes escaping from cultivated crops into wild relatives

Response:
Some are concerned that the transgene might escape from the cultivated GM crop into wild relatives. In the case of herbicide-tolerant crops, the gene responsible for herbicide tolerance might move to nearby relatives, thus creating “superweeds”.

Although the transfer of genes from the GM crop to the non-GM wild relatives is a legitimate concern, the development of resistance to herbicides already exists as a result of natural selection, evolution and long-term exposure to certain herbicides. Whether the crop plant is GM or not, the continued development of new and safer herbicides is required. So far, no threats from “superweeds” have arisen so far as a result of GM herbicide-tolerant crops.

Issue:
Potential for pests to evolve resistance

Response:
Crop pests naturally develop resistance to insecticides over a long time, whether the crop plant is GM or not. When insecticidal sprays are continuously used on non-GM crops, resistant insect strains will eventually emerge. The same process occurs in GM crops.

This problem, however, can be managed. In Bt sprays (not the GM Bt corn) for example, it has been shown that Bt resistance is linked to several different genes on different chromosomes. Thus, in order to keep those genes at low levels, an emerging Bt-resistant insect must mate with a non-resistant one. This can happen when part of the field is planted with the non-GM counterpart. This area, called a refuge, is where the Bt susceptible insects can survive to mate with the resistant ones coming from the GM crop-planted part of the field. Planting of a refuge therefore delays the emergence of BT resistant pests.