Irradiated Food Irradiating (照射)fruits, vegetable, pork and chicken to kill insects and bacteria has been approved by the Food and Drug Administration over the past decade or so. Irradiation of other meats, such as beef and lamb, is being reviewed. Federal approval dose not require that industry adopt the process, and few food processors presently offer irradiated products. Market studies have shown that many consumers are afraid that eating irradiated food may cause cancer, despite scientific studied that prove the safety of treated food. Some people argue that more severe government inspection, higher food-safety standards, and more careful food-preparation practices by consumers are all that is needed to ensure that food is safe. Consequently, companies cur rently see no need to spend millions of dollars outfitting(配备) processing plants with the equipment necessary for a process that very few shoppers are in favor of. All supermarkets that sell irradiated food must label that food either directly on the packaging or in the case of bulk items like fruits and vegetables by placing a sign nearby. There is no requirement for the labeling of irradiated food served by chain restaurants or hospitals that buy directly from distributors, nor any regulations for products that contain irradiated ingredients. Presently, the FDA allows food to be treated with types of radiation-gamma rays, high-energy electrons, and X-rays-and sets limits on doses(辐射量) depending on the type of food. The principle is that the does to be used for a certain type of food should not exceed the amount that is sufficient to kill most harmful insects and bacteria present in it. Different types of food, because of their different molecular(分子) compositions, may require different doses of radiation. According to the passage, killing insets and bacteria present in food by irradiating ______.