Safe Food_ Bacteria, Biotechnology, and Bioterrorism - Marion Nestle [104]
Industry scientists working on early food biotechnology projects considered their work fundamentally similar to conventional genetics. If the foods did pose risks, these would be small and outweighed by benefits. Indeed, industry leaders believe that the projects are so interesting and potentially beneficial (and, of course, economically viable) that they raise no safety issues whatsoever. Critics disagree. In particular, they question the safety of genetic engineering manipulations that use (1) genes from bacteria responsible for diseases in plants, (2) genes for antibiotic resistance as “selection markers” (see page 176), and (3) regulatory DNA sequences transferred from one organism to another. They wonder whether “in the transgenic plant the harmonious interdependence of the alien gene and the new host’s protein-mediated systems is likely to be disrupted in unspecified, imprecise, and inherently unpredictable ways.”11
Critics ask whether the new proteins made by genetically modified plants might cause allergic reactions. They question the wisdom of planting vast areas of land with crops modified to resist herbicides or insects: will such plants transfer herbicide resistance to unwanted weeds, or toxin resistance to harmful insects? Government regulations do not require agricultural biotechnology companies either to answer such questions in much detail or to do very much to identify the potential consequences of releasing transgenic foods into the environment (consequences such as those that occurred with StarLink corn). The government not only fails to require labeling of genetically modified foods but actively opposes attempts to label such foods. All of this means that companies can decide for themselves what foods to produce and market, and consumers have little choice in the matter. Questions of safety, therefore, cannot be addressed without dealing with issues of regulation, oversight, trust, and control—politics. With politics in mind, we can now examine the principal safety issues: allergenicity, antibiotic resistance, and harm to the environment.
Allergens
It makes sense to think that introducing the DNA for a new gene into a food would also cause that food to make a new protein. That, after all, is the function of genes and the very purpose of food biotechnology. It also makes sense that some people might develop allergic reactions to the new protein; some proteins are allergens. In theory, any food protein can be allergenic. In practice, however, just eight foods cause 90% of food allergies: milk, eggs, soy, and wheat in children, and peanuts, tree nuts, shellfish, and fish in adults. When susceptible people eat these foods, most react with mild symptoms (itching, for example), but for others the result can be deadly. True food allergies—those that involve components of the immune system and threaten life—are relatively rare. Doctors diagnose them in less than 8% of children and 2% of adults in the United States.12
Whether the new transgenic proteins in foods might cause allergies is not easy to answer, mainly because many of the transgenes come from microbes never used as food. Furthermore, food allergies are a highly neglected area of medical research, and depressingly little is known about the structural features of proteins that induce immune reactions. Because exceptions are frequent, the few generalizations are highly tentative: allergenic proteins appear to occur in high concentrations in foods, to share some structural similarities, to be less easily