Why are transgenic organisms different from conventional ones?

Why are transgenic organisms different from conventional ones?

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By Ana Lucía Bravo

The spread of transgenic organisms such as foods causes alarm and concern, as there are arguments to indicate that its approval has revolved around a letting go of the international scientific community and regulatory entities.

Genetic engineering is a totally different technique than the practices that have been used in conventional plant breeding since the initial development of agriculture 10,000 years ago, which have evolved over millions of years of development. The risks associated with genetic engineering are inherent in the first place to the same technology that develops them since they are based on the principles of Molecular Biology established by Francis Crick, according to which:

* Genes determine the characteristics of an organism in a unidirectional and irreversible way;
* Genes and genome are stable, information is transmitted unchanged, except for rare mutations;
* Genes are not modified by the environment, nor do they act in response to it, but change at random;
* Genes are stable and do not undergo variations; After being inserted into a new organism, the genes do not change places, they remain where they were introduced. (Ho, 1999)

However, at the beginning of the eighties, this central dogma began to be debated, then the concept of the "fluid genome" appeared, according to which:

* Genes work in a much more complex network where causality is not linear but multidimensional and there is feedback, that is, the whole system is connected: genes influence other genes, proteins influence other proteins and even proteins can influence in the genes;
* Genes are subject to regulation and influence by the physiology of the organism and the environment; * Genes are dynamic fluids that change according to the pressure of the environment;
* Genes jump horizontally between unrelated species, that is, not due to the vertical transfer of genes from parents to children that occurs in reproduction but through infectious processes in which DNA takes naked DNA and incorporates it into another organism. (Ho, 1999)

From this perspective, the change of a characteristic can cause a series of changes or interferences in the genome of the recipient organism.

Secondly, there is the technique used that allows genetic material to be recombined in the laboratory between species that do not interbreed in nature. New genes and combinations of genetic material are introduced into the recipient organism; These artificial constructs are derived from the genetic material of pathogenic viruses and other gene parasites, as well as bacteria and other organisms, and include genes that encode resistance to antibiotics. Constructs are designed to break down species barriers and overcome prevention mechanisms that prevent the insertion of foreign genetic material into genomes. In other words, the transgenic organism does not only include the gene that gives it a new characteristic, but rather a set that contains several different components is included. Additionally, the artificial constructs are integrated into the genome of the recipient organism in a random way, giving rise to unpredictable effects, including significant abnormalities in both animals and plants, as well as the appearance of unexpected toxins and allergens in food crops. Consequently, it is impossible to perform a quality control, even more so if the instability of transgenic lines is considered, which makes it practically impossible to carry out a risk assessment. (Ho, 1999)

Health risks

The spread of transgenic organisms such as foods causes alarm and concern, as there are arguments to indicate that its approval has revolved around a letting go of the international scientific community and regulatory entities.

Ho and Steinbrecher (Ho, M., Steinbrecher R., 1998) point out that a “safety assessment” was conducted as opposed to precaution, intended to give rapid approval of transgenic organisms at the expense of safety considerations. In other words, the studies on which the safety of GMOs is based have been criticized for omitting certain considerations, for ignoring scientific evidence and for being carried out by the same companies.

The Joint Report of FAO and WHO on Biotechnology and Food Safety, resulting from an Expert Consultation held in October 1996 in Rome, is the document that has served as a model for the evaluation of food safety. However, this has been questioned for several reasons: a) talk about the benefits of technology; b) evade responsibilities of food safety, or aspects such as the production of nutraceuticals; c) erroneously argue that genetic engineering does not differ from conventional breeding; d) not taking into account long-term impacts on health; e) ignore the existing scientific evidence on hazards already identified, such as horizontal transfer and recombination of transgenic DNA (Ho, M., Steinbrecher R., 1998)

The most controversial point and the one that has attracted the most criticism from Ho and Steinbrecher is the adoption of the “Principle of Substantial Equivalence”. This principle implies that a new food or food component is substantially equivalent to an existing food or food component, it can be treated in the same way as this in relation to safety. In other words, the new food or component is as safe as the conventional one. However, it remains to specify which are the comparison parameters. The report does not state what tests will be required, what specific tests will be performed.

“Establishing substantial equivalence is not a safety assessment itself, but a dynamic, analytical exercise in assessing the safety of a new food relative to an existing food. The baseline traits for substantial equivalence comparisons should be flexible and will change over time according to the changing needs of manufacturers and consumers and with experience. "

In practice, companies are free to compare anything, run the least rigorous tests to quickly claim substantial equivalence. For example, detailed molecular characterization of the transgenic insert is avoided to establish genetic stability, gene expression profiles, metabolic profiles, etc., which would have revealed the presence of unintended negative effects.

This principle, according to the authors, leads, for example, to the approval as substantially equivalent of potatoes that in field tests showed marked deformities in the morphology of the sprout and low tuber yield with the presence of few small and deformed tubers, because the quality of the tuber did not suffer major variations.

The approval process for transgenic foods by the US Food and Drug Administration, FDA, took place based on this same principle. Thus the commercialization of the transgenic tomato Flavr Savr from the Calgene company was approved. This process has been questioned by Belinda Martineau, the scientist who conducted the safety studies, who states that: “Calgene's tomato should not serve as a safety standard for this new industry. No genetically engineered product should do. " (Martineau B, 2001)

In fact, according to a secret FDA memorandum, it was learned that the Flavr Savr tomato had not passed the required toxicological tests and that the FDA had ignored the warnings of its own scientists that genetic engineering is a new area and poses risks. new. (Independent Science Group, 2003)

Since then, very few serious and independent studies have been carried out in relation to the safety of transgenic organisms. However, it is known from two reports that revealed harmful effects in animals fed transgenics. The first showed that rats fed transgenic Flavr Savr tomatoes had ulcer onset in the stomach lining. The second one carried out with male mice of months of age and fed with transgenics revealed a process of cellular proliferation in the lower small intestine. (Fares, N; Sayed. A., 1998).

The next major study is being conducted by Arpad Puztai of the Rowett Institute with funding from what was then the Scottish Office of the Agriculture, Environment and Fisheries Department (SOAEFD) to assess environmental and health risks. lines of transgenic potatoes modified, by a group of British scientists, in the same experiment with the aim of giving them resistance to aphid pests. Studies have shown the following (Puztai, 2002):

• The two lines of transgenic potatoes were not substantially equivalent in composition to each other or to the parental (conventional) lines.
• The diet containing transgenic potatoes interfered in some cases with the growth of young rats and with the development of some of their vital organs. Promoting changes in the intestinal structure and function and reducing its immune response. This is in contrast to another group of rats that were fed conventional potato and the transgenic protein was added, which did not present problems.

These facts show on the one hand that, as indicated above, the concept of substantial equivalence does not offer any guarantee of safety and, on the other, that the changes that occurred were due to the genetic modification itself, that is, to the genetic construction inserted in the DNA of the potato genome, and not to the action of the introduced gene. (Pusztai, A; Bardocz, S; Ewen S. 2003)

These tests also showed that it is possible to carry out “toxicological studies and that the safety of transgenic foods must be established from the short and long-term feeding of young animals and from the metabolic and immune response studies of the same, since they are the most vulnerable and the most likely to respond to and manifest any nutritional and metabolic stress that affects development ”. (Independent Science Group, 2003)

This last sentence deserves all the attention, since many of the transgenic products have the target population of infants, children and pregnant mothers (in which case the fetus is developing). So far there are no studies that demonstrate the safety of transgenics in these groups. As the former FDA employee puts it, “Simply claiming that these foods are safe and there is no scientific proof to the contrary is not the same as saying that numerous tests have been done and here are the results” (Martineau B, 2001) . Similarly, Stanley Ewen, histopathologist at Grampian University Hospital Trust and head of the Colon Cancer Research Pilot Program in the Grampian Region, summarized the situation as follows: “It is regrettable that there are very few trials available in transgenic food animals for humans, both in the public domain and in the scientific literature. The corollary is that transgenic foods have not been shown to be risk-free and, indeed, the experimental scientific results available are cause for concern ”. (Ewen S., 2002)

Therefore, contrary to what is constantly argued, GM foods never passed the necessary tests that could have established their long-term safety. On the other hand, the few tests carried out give indications of the potential impacts that they can cause to health.

In the short term, one of the health risks is the appearance of allergies. At present, only a dozen foods can cause allergic reactions, mainly due to proteins present in those foods, but with genetic engineering this number can increase considerably, since non-traditional proteins are incorporated into foods for which there is no information whatsoever. on its allergenic properties. Therefore, it is possible that the commercialization of foods that contain genetically modified products, causes that particularly sensitive individuals develop allergies to foods that they previously consumed without danger. If anaphylactic shock occurs, an allergy can be fatal. (Ho and Tapesser, 1997)

On the other hand, the use of antibiotic resistance genes as part of the genetic insert may lead to an increase in resistance to antibiotics for some bacterial diseases in humans. This fact is already a public health problem for some diseases today. (Tschape, 1994)

A sample of the concern around these two issues is the pronouncement of several of the most recognized and prestigious health agencies in the world, such as: the French Agency for Food Safety, the Royal Society of Canada and the Association British Medical.

The three agencies (AFSSA, 2001) (The Royal Society of Canada, 2001) (BMA, 1999) in different reports indicate that more rigorous tests should be conducted on long-term toxicity, questioning the current procedure of substantial equivalence. They point out that measures must be taken to reduce the risk of allergies and that the use of genes with resistance to antibiotics is a minimal but unacceptable risk that consumers should not be subjected to. Finally, they call for the use of the Precautionary Principle to avoid irreversible damage.

Ana Lucía Bravo from the Network for a GMO-free Latin America


AFSSA, 2002. Agence Française de Securité Sanitaire des Aliments, Résumé del’avis de l’AFSSA sur l’evaluation des risques relatifs à la consommation de produits alimentaires composés or issus d'organismes genetically modified. January 31 2002.;

Brithish Medical Association, 1999. Council on Science and Education. The Impact of Genetic Manipulation on Agriculture, Food and Health. Recommended Position Document.

Ho, M.W., 1999. Genetic Engineering Dream or Nightmare? The Brave New World of Bad Science and Big Business, Gateway, Gill & Macmillan, Dublin.

Ho and Tapesser, 1997. Cited by Ho, "La insanta Alianza", The Ecologist, vol.27, No. 4. (Madrid: July / August 1998).

Independent Science Group, 2003. In defense of a sustainable world without transgenics. Written by Mae-Wan Ho and Lim Li Ching. July 2003. London.

Video: Why Meat is the Best Worst Thing in the World (July 2022).


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