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  3. The food irradiation process is a simple one. The new US plant, Vindicator o

The food irradiation process is a simple one. The new US plant, Vindicator o

游客2023-07-18  54
问题     The food irradiation process is a simple one. The new US plant, Vindicator of Florida Incorporated in Mulberry, Fla. , uses a material called cobalt (钴) 60 to irradiate food. Cobalt 60 is radioactive isotope (同位素) (form) of the metallic element cobalt. Cobalt 60, which gives off radiation in the form of gamma rays, is also used for radiation therapy for cancer patients and for sterilizing (消毒) hospital equipment. The radioactive isotope is created by bombarding cobalt with subatomic particles in a nuclear reactor. However, irradiation plants do not themselves contain nuclear reactors.
    In the irradiation plant, food is exposed to thin rods of cobalt 60. The rods give off gamma rays, which disrupt chemical processes in contaminating organisms. The disruption breaks down the cell walls of organisms or destroys their genetic material. The dose, set by the US Food and Drug Administration (FDA), is enough to kill organisms on food, but not enough to produce significant changes in the food itself.
    Although irradiation slightly decreases the nutritive value of foods, the loss is less than that produced by some other methods of food preservation. Canning, for example, results in a much greater loss of nutrients.
    Those who object to irradiation say that the process may create substances not found in non-irradiated food. Since the 1960’s researchers have studied irradiated food at microscopic levels to try to find such substances, called unique radiolytic (辐射分解) products. After reviewing these studies, the FDA determined that compounds formed during irradiation were similar to substance found in non-irradiated foods and were not dangerous to consume.
    Destruction of microorganisms that cause illness is an important goal of irradiation. About 250 million cases of food poisoning or 1 per person — occur every year in the US, according to FDA estimates. Food poisoning can cause vomiting (呕吐), diarrhea (腹泻), fever, headache — and, occasionally, death.
    Because of the apparent safety of food irradiation, and the problems presented by contaminated food, scientific groups — including the American Medical Association, the World Health Organization, and the United Nations Food and Agriculture Association — have voiced nearly universal support for the process. Worldwide, 38 nations have approved irradiation for 355 products.
    Like microwave ovens, food irradiation has aroused apprehension and misunderstanding. Yet it has been scrutinized (审查) more thoroughly than other methods of food treatment that we have come to regard as safe, and it appears to be a method whose time has come. [br] Gamma rays used to irradiate food______.
选项 A、are generally not strong enough to destroy contaminating organisms
B、do not bring about significant changes in the food itself
C、may destroy some of the nutrients in the food
D、should be submitted to FDA for approval
答案 B
解析 可定位在第2段最后一句：The dose，set by the US Food and Drug Administration(FDA)，is enough to kill organisms on food，but not enough to produce significant changes in the food itself(由美国食品及药品管理局规定的照射量足以杀死食物上的细菌，但却不能对食物本身产生很大影响)，该句中的The dose，指的就是题干中的Gamma rays used to irradiate food(用于照射食物的伽马射线)，故选项B正确。
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