Letter: Unique peril of engineered food crops

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Sir: I write in an effort to dispel the common myth that the use of genetic engineering to produce new varieties of crops and farm animals is a natural extension of traditional cross-breeding methods (Suzanne Moore, 20 September; J Stocker, letter, 23 September).

In contrast to traditional methods, genetic engineering involves transfer of genetic material between totally unrelated organisms. Genes from viruses, bacteria, animals as well as unrelated plants have been engineered into crops. This circumvents natural species barriers and brings about combinations of genes that would never occur naturally.

This could be hailed simply as yet another great advance for modern agriculture if is wasn't that this is an imperfect technology with inherent dangers. The generation of genetically modified ("transgenic") plants and animals not only involves the use of artificial genetic combinations (such as parts of plant viruses linked to bacterial genes), but also its random splicing into the DNA of the host organism. This gives rise to an unpredictable component with regard to the functioning of both the host and introduced gene unit. (Normal gene control is preserved during cross-breeding of closely related species).

Furthermore, it is assumed that the protein product of the newly introduced gene will function in exactly the same way as it does in its native host, which frequently will not be the case. It is therefore not surprising to find that genetic engineering can result not only in reduced nutritional value but also in the unexpected production of novel toxins and allergens. It is the unpredictability of these outcomes that is most worrying. This argues strongly for general toxicity testing, perhaps something similar to that used for pharmaceuticals, and full labelling for all of these products. This will also allow the consumer to make an informed choice and truly "vote with their supermarket trolley" (leading article, 20 September).

Given that we have safe natural alternatives we should not be surprised to find that the Prince of Wales and others questioning the use of this technology, since once out in the field genetic pollution cannot be cleaned up and will be passed on to all future generations.


Senior Lecturer in Molecular Biology

London SE1