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  3. The food irradiation process is a simple one. The new US plant, Vindicator of Florida Incorporated in Mulberry, Fla. , uses a ma

The food irradiation process is a simple one. The new US plant, Vindicator of Florida Incorporated in Mulberry, Fla. , uses a ma

admin2012-08-10  12
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.
Cobalt 60, besides irradiating food, is also employed to______.
选项 A、detect metallic flaws
B、run a nuclear reactor
C、cure cancer patients
D、strengthen concrete walls
答案C
解析 可定位在第1段第4句：Cobalt 60…is also used for radiation therapy for cancer patients and for sterilizing hospital equipment(钴60……也用于对癌症病人进行放射治疗以及对医院仪器设备进行消菌杀毒)，在众选项中，只有C项cure cancer patients(治疗癌症病人)符合题意，故正确选项为C。
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