In general, the foods produced through genetic engineering techniques are less likely to have unforeseen undesirable traits than foods developed through traditional breeding techniques, because of the greater precision that gene transfer allows.
Some of the concerns about the safety of genetically engineered food plants include:
Marker genes are a way to determine if the insertion of the desired DNA was successful. For example, when Calgene developed the FLAVR-SAVR tomato, they used a kanamycin-resistance gene in the transgenic tomato plant. They linked the desired gene with a kanamycin-resistance gene. They grew the transgenic plants in media containing kanamycin, an antibiotic. Seeds with the kanamycin-resistance gene were able to grow, while seeds that lacked the kanamycin-resistance gene were killed by the kanamycin. Thus they were able to be sure that the plants growing in that medium were successfully transformed (i.e., had the desirable gene).
However, concerns have been raised as to the safety of kanamycin-resistance. If bacteria in the digestive tract, for example, were to acquire the kanamycin-resistance gene, then kanamycin would no longer be clinically useful against those bacteria. The FDA evaluated the kanamycin-resistance marker gene and concluded that 1) the chance of a bacterium acquiring the trait was very small, and 2) kanamycin is a very toxic antibiotic and has very limited oral clinical use; it can only be used in situations where patients are not consuming food.
A study published in the New England Journal of Medicine(Nordlee-J-A. Taylor-S-L. Townsend-J-A. Thomas-L-A. Bush-R-K. Identification of a Brazil-nut allergen in transgenic soybeans N-Engl-J-Med. 1996 Mar 14. 334(11). P 688-92) demonstrated that an allergen from a food known to be allergenic can be transferred into another food by genetic engineering. To improve the nutritional quality of soybeans, methionine-rich 2S albumin from the Brazil nut was introduced into soybeans. The soybean extract showed allergenic properties when it was tested on patients who were known to be allergic to Brazil nuts. The FDA believes that proteins derived from commonly allergenic sources should be presumed to be allergens and special labeling would be required, unless scientific evidence demonstrates otherwise.
Back to Safety of Products of Plant Biotechnology
Prepared Summer 1997 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.