Genetic modification can transfer allergies from foods that people know they are allergic to foods they think are safe. About 2% of adults and 8% of children have true food allergies and about one quarter have reacted adversely to some type of food.
Failure to label GM foods," says the CI campaign kit, "would mean that people with allergies have no way of knowing whether they are eating potentially risky foods or, in the event of problems, what ingredient provoked the reaction
Activists also highlight the uncertain long-term effects on nutrition and health posed by GM foods. They point to the use of antibiotic-resistant genes as "markers" (to track the gene carrying the trait being transferred) in GM crops. This, they say, could add to the problem of antibiotic resistance. Genetic manipulation could also increase levels of natural plant toxins in foods or create entirely new toxins in unexpected ways.
GM organisms also threaten to diminish biological diversity, say the activists. The cultivation of GM organisms, they add, could lead to the wiping out of weeds and insects. If that happens, the species that depend on them will also suffer.