(Excerpt from: Assessing the safety and nutritional quality of genetically engineered foods by John Fagan)
To protect the health and safety of the consumer, it is necessary to ascertain that all genetically engineered foods are free of allergens and toxins, and are unaltered in nutritional value before they are placed on the market. To assure the safety of genetically engineered foods, it is essential to test for health hazards derived from all three sources of risk presented above, (1) risks foreseeable based on the characteristics of the unmodified organism, (2) risks foreseeable based on the characteristics of the gene source, and (3) risks due to unintended changes in functioning of the food-producing organism caused by genetic manipulations, themselves.
At present, regulations in most countries governing the safety testing of genetically engineered foods focus almost entirely on health hazards that can be anticipated from the characteristics of the unmodified organism, and the gene source. However, accidental introduction of allergens and toxins through genetic manipulations and unintended alterations in nutritional value resulting from genetic manipulations constitute a very real source of health risk from genetically engineered foods. Therefore safety testing should be structured in such a way as to detect and eliminate products that contain these hazards. The discussion below presents science-based arguments that establish the actuality of these genetic engineering-induced hazards, and presents testing strategies capable of protecting consumers from these as well as other hazards.
"Genetically Engineered Food - Safety Problems"