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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  36
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.
The passage may be taken from______.
选项 A、a news report
B、a textbook of food processing
C、a book of popular science
D、a manual of food irradiation
答案D
解析 全文的主题词就是food irradiation(辐照食物消毒法)，谈及其定义、过程、可能引发的问题、人们的误解、在当今社会的应用等，显然应该是推广介绍辐照食物消毒法的宣传资料，而其他选项a news report(新闻报道)，a textbook of food processing(关于食物加工的教材)和a book of popular science(大众科学书籍)都过于笼统，故正确选项为D。
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