Safety of Genetically Modified Food

1. Safety has utmost priority

Genetically modified (GM) food, food additives, and processing auxiliaries are subject to comprehensive safety tests before they can enter the marketplace. The same applies to animal feeds made using genetically modified crops, an aspect that shall be covered soon by the Novel Feed Regulation currently being elaborated. Applicants for a marketing licence are obliged to show, on the basis of tests that have been conducted, that the products in question do not entail any risk for humans, animals, or the environment.
Germany and the EU have at their disposal strict and comprehensive regulatory conditions in the area of genetic modification legislation. GMO foods, GMO food additives, GMO processing auxiliaries, and animal feeds produced using genetically modified plants all require official approval, which can be issued only after an exhaustive scientific appraisal of safety-related issues has been made.

2. Allergies

Techniques of genetic modification have allowed food allergies to be much better researched than was the case a few years ago. Roughly 2% of all adults and 5% of all children exhibit allergic reactions after the consumption of certain kinds of food.
The naturally occurring allergens of most relevance are found in only ten different kinds of food. These allergens are responsible for 90% of all food-related allergies

Source: Publication of the "Schwerpunktprogramm Biotechnologie" of the Swiss National Foundation "Gentechnisch veränderte krankheits- und schädlingsresistente Nutzpflanzen. Eine Option für die Landwirtschaft?" (1996), p 56.

Many of the most relevant food allergens have been characterized. One relatively new finding is that allergens share similar properties, such as molecular size or the speed with which they are degraded in the gastrointestinal tract.
These facts make it possible to identify allergens using biochemical testing methods.
Genetic modification is used to introduce individual genes with known properties into a plant so it is possible to precisely test the risk of allergic potential in connection with genetically modified food products.
By comparison when vegetable products such as potatoes, rice, maize, or more recently exotic fruits such as papayas or kiwis were first consumed, the human immune system came into contact with thousands of new proteins that had never before been part of our diet.
The results of comprehensive investigations have revealed no increased allergy risk connected with genetically modified plants that have been approved so far compared with conventional plants and their products.
Neither do the genes and proteins that have been used so far (herbicide- and antibiotic-resistance genes, insecticidal proteins from Bacillus thuringiensis, or viral proteins) originate from sources with an allergenic potential, nor have comparisons with known allergens demonstrated any similarities. Most of the specified proteins have already been part of the human diet.
In the approval procedure for genetically modified food, the allergenic potential of the protein introduced into the plant must be investigated. The following tests are carried out:

Allergenicity testing:

Genetic modification can be expected to contribute towards the avoidance of food allergies as allergens can be inactivated or completely eliminated by these techniques.
This is being attempted in Japan with rice, which contains proteins that trigger an allergic reaction in Japanese people in particular. Efforts to cultivate such a hypoallergenic rice variety are currently being undertaken in various laboratories; as yet, however, these efforts have yielded only partial success, since it has not been possible to fully eliminate all allergens.
Genetic modification is also very helpful in the areas of diagnosis and elucidation of the causes of allergies.
A number of new anti-allergy pharmaceuticals have already been developed; these are currently undergoing clinical trials

3. Toxic substances

Some plant toxins have a closely defined spectrum of activity; in other words they have a toxic effect only on a specific range of pests and pathogens. Others have a relatively broad spectrum of activity, being effective against a wider number of pests, but also in many cases against animals and humans. Defence toxins produced in genetically modified crop plants - for example insecticidal proteins from Bacillus thuringiensis (Bt maize) - have a highly selective and specific effect against only a few pests.
The Bt protein has been an ingredient of our diet for a considerable time, having been in use in ecological farming to combat pests for some 40 years. So far we have consumed it without any harmful consequences. With genetically modified plants it is possible to subject the products of the newly introduced resistance gene to specific toxicological investigations. These investigations are a constituent part of the official approval procedure for genetically modified foods.
In a risk-benefit assessment, the potential toxicological risk entailed by new genetic modification resistance strategies must be weighed up against the risks posed by alternative strategies on a case to case basis.

4. Antibiotic resistances

Genetically modified crops in some cases contain antibiotic-resistance genes as marker genes. Critics of genetic modification techniques fear that these genes could be transferred to intestinal bacteria when such foods are eaten and the antibiotics in question would become ineffective when administered normally. So far, however, no such a gene transfer has been observed. Comprehensive and exhaustive scientific investigations have shown that genetic material is degraded and thus deactivated by digestion The probability that genes survive digestion intact and are then taken up by intestinal bacteria and stably incorporated in their own genetic material, is extremely low.
It is thus highly improbable that antibiotic-resistance genes from genetically modified plants are transferred to intestinal bacteria after the plant in question is eaten by humans or animals. (Although bacteria exchange genetic material with each other, comprehensive scientific investigations under natural conditions have not shown a single case of transfer of genetic material to microorganisms as a result of the consumption of vegetable foods or the decay of vegetable material).
The resistance genes employed in genetically modified crops occur naturally on a widespread basis in the environment, including within the human gut. Genetic modification would not result in any appreciable rise in the number of resistant bacteria, even if there were any transfer of resistance genes to bacteria, which itself is highly improbable.
An example of an investigation in this connection involves the assessment of the safety of the FlavrSavr® tomato. In a worst-case scenario, the genes survive their passage through the digestive system, are taken up by gut bacteria, and subsequently incorporated into their genetic material, with the protein responsible for the resistance then being produced as a consequence. Even if this highly improbable event were to take place, the maximum increase in the number of antibiotic-resistant bacteria resulting from the consumption of FlavrSavr® tomatoes with our nutrition would be 0.000001%.
Medical treatment with antibiotics is thus not in the least impaired as a result of the consumption of genetically modified plants containing antibiotic-resistance genes.

5. Emergence of resistant pests

The adaptation of pests to plant resistance due to selection pressure is a phenomenon that has been known to science for a long time. The emergence of resistant pests does not depend on the method of cultivation. It therefore does not matter whether the plant-protection mechanisms have been implemented by traditional or by genetic-engineering methods. Bt-resistant pests for example, were present before the use of genetically modified crops. The emergence of resistant pests depends on nature of the resistance strategies (e.g. one or more resistance genes), the biological characteristics of the pest, and the cultivation conditions (e.g. monocultures).
Clearly, manufacturers of genetically modified plants have a vested interest in avoiding or at least considerably slowing down the emergence of resistant pests. A possible strategy to defer the onset of resistance in a pest population is the development of refuges: a section of the field is reserved for non-resistant plants to serve as a refuge for the pest in question. The reduced selection pressure can then slow down the emergence of resistance. Research includes the incorporation of several resistance genes and the development of a temporally and locally restricted production of the resistance-mediating proteins in the transgenic plant in question.

6. Gene transfer

The transfer of genes between plants of related species is a natural occurrence. Exchange of disease and pest resistance for example, from arable crops to related wild species and vice versa, has always taken place.
The emergence of new species with a "weed character" is also known in conventional cultivation (e.g. derivatives of cultivated sugar beets and wild beets). Extensive field trials in the UK and elsewhere have indicated that the likelihood of genes from GM crops spreading into the non-farm environment is no different from that of the conventional crops from which they are derived.
The likelihood of gene transfer to wild relatives therefore depends on the species of crop and the location in which the crop will be grown. The transfer of genes is only possible in cases in which related partners are flowering in close proximity. There are some plants (e.g. maize, soybean, tomato, potato) that have no related wild species in Europe. The transfer of a new gene to wild plants can thus be discounted in these cases. In the case of plants such as sugar beet, oilseed rape, and alfalfa the exchange of genes with related wild plants is possible. For example, relatives of oilseed rape can be found growing near crops in the UK, whereas cereal relatives are rare. It may therefore be necessary to take special measures with the former. The transfer of genes between cultivated and wild plants means that the newly introduced gene spreads from the agricultural ecosystem into the natural ecosystem. In such cases, studies must be undertaken before large-scale agricultural cultivation of genetically modified plants, to investigate whether the wild version of the plant could be given a competitive advantage by the gene acquired from its cultivated relative.
Although comprehensive investigations have been conducted under natural conditions, it has at no time been possible to demonstrate that the consumption of vegetable foods or the decay of vegetable materials has resulted in the transfer of plant genes to microorganisms (horizontal gene transfer, abbreviated to HGT).
Consequently, new risks associated with the HGT phenomenon are excluded among the genetically modified crops and related products that have so far been given marketing approval. The eating of genes does not entail any hazard to our health. Each day we eat genes in our food.
The same thing happens to the genes that have been newly introduced into transgenic plants -which after all originate from nature - in our digestive tract as happens to all other genes that we consume with our food: they are rapidly broken down into their basic constituents. Every normal meal we eat - for example a portion of roast beef - contains about one gram of genetic material, an amount equivalent to roughly one teaspoonful of DNA.