First, it is essential to exclude the evaluation of pharmaceutical products such as oral vaccines, immune modulating proteins, hormones, antimicrobials and growth factors from the present considerations. Such products should be considered separately and reviewed independently from the current annex; they are inherently hazardous and require special consideration under a separate annex.
Plants modified for nutritional or health benefit should include only those with enhanced vitamins, minerals, antioxidants (for example plant phenolics (flavonoids) known to fight cancer) and enhanced primary metabolites such as essential amino acids and health promoting reduced linolenic fats. Recombinant genes derived from a plant used to modify another plant species should not automatically be deemed safefor humans. This is highlighted in a recent investigation in which a protein from bean was found immunogenic when expressed in pea . Specifically, immunological assessments carried out for the firsttime on a transgenic protein revealed that post-translational processing subsequent to gene transfer into an alien species introduced new antigenicities that turned a previously harmless protein into a strong immunogen. In addition, the transgenic protein promoted immune reactions against multiple other proteins in the diet.
As practically all the transgenic proteins involvecross-species gene transfer, they will be subjected to different post-translational processing, and hence they too, will have the potential to become immunogenic. And yet, none of the transgenic proteins that have been commercially approved has been tested. This omission is a most serious public health issue, and the Independent Science Panel has already called for an immediate ban on all GM food and feed until proper assessment on the immunogenicity of the transgenic proteins has been carried out . This should apply all the more so to GM crops coming to the market that are meant for human consumption.
Nutritional enhancement and traits for improved health may be developed using conventional breeding or marker assisted selection then those traits combined with recombinant traits such as herbicide tolerance and/or insect resistance. Monsanto’s Vistive soybean, for example, combines natural genes reducing the oil content of linolenic acid, but also has transgenes conferring the Roundup Ready trait. The transgene activity is known to affect the precursor pools leading to formation of trans fatty acids . Thepoint is that when nutritional or health traits are combined with transgenic ones, the interaction of the two should be fully evaluated. Interactions between transgenic nutrition and health traits and other genetic modifications within a cultivar should be carefully evaluated, as should interactions between conventional nutritional or health traits with transgenes in recombinant strains with which they are combined. A number of nutritional- and health-related transgenic plants are being developed (see Box). We must ask if these developments provide real benefits for people,and whether there are safer, cheaper and moreeffective alternatives for producing thenutritional/health benefit. More importantly, in every single case, it is necessary to assess the GM plant, the transgene and protein for toxicity and immunogenicity, for reasons given above.
Animal studies should be undertaken with every modified crop or in crosses between modified crops and crops bearing genes for nutrients or health products that have been enhanced using conventional breeding or marker assisted breeding. It has become common practice to used crude measures of size to evaluate the outcome of feeding experiments. That is notacceptable. Full tissue and organ necropsy is required in every case to detect cell damage and to identify pre-cancerous lesions. In addition, immunogenic and toxicity tests must also be carried out.