So called "edible vaccines" and "biopharming" (i.e. the production of vaccines or other bioactive substances in edible crops) can be put to hostile use. In the past decade, genetically engineered plants have been investigated as a means to produce and deliver vaccines. There are already a variety of research reports demonstrating that engineered plants can elicit an immune response in humans, and clinical trials on humans are currently underway to test vaccines produced in edible crops. These vaccines may be isolated from the plant for further processing or directly delivered to the patients by consumption of the engineered plant.
Vaccines are only one type of bioactive substances being produced in edible crops. Several US companies are using genetically engineered crops to produce industrial enzymes, growth hormones, and other potent pharmaceutical compounds. These techniques pose a serious risk to human health and the environment, especially when the highly active pharmaceuticals are introduced into edible crops.
The possibility of abuse of these crops and/or the underlying technology for hostile purposes is serious. In long term conflicts, it may be tempting to weaponize engineered crops, spiking them with, for example, disease-inducing (e.g. cancer) or debilitating compounds (e.g. affecting human or animal fertility) or built-in deficiencies that could lead to crop failure. Such "weaponized" germplasm may thereafter be introduced in the target country's seed supply and consequently its food supply through covert actions or simply by means of seed sales or humanitarian aid. This may not be possible with crops that are exported by the target country, as, given today's global market, the spiked food/feed could end up in the aggressor's food supply...