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  3. Arsenic, a naturally occurring poison and carcinogen found in ground water, is strongly linked to adult-onset diabetes, U. S. re

Arsenic, a naturally occurring poison and carcinogen found in ground water, is strongly linked to adult-onset diabetes, U. S. re

admin2011-02-25  81
问题     Arsenic, a naturally occurring poison and carcinogen found in ground water, is strongly linked to adult-onset diabetes, U. S. researchers said on Tuesday. Odorless, tasteless, colorless and easily soluble in water or wine, arsenic has long been a feared poison. A heavy dose is detectable in a corpse, but researchers say small amounts of arsenic may sicken people gradually.
    Dr. Ana Navas-Aeien and colleagues at Johns Hopkins University in Baltimore found a " relatively strong " association between commonly found levels of arsenic in urine and type 2 diabetes in a study of American adults. " It seems there is maybe no safe level of arsenic. " Navas-Acien said in a telephone interview. " Worldwide it’s a huge problem, " she said. " As water becomes a scarce resource. the situation becomes even more serious. "
    Arsenic raises the risk for cancers of the bladder, lung, kidney, skin and, possibly, the pros tate, Navas-Acien said. The 20 percent of nearly 800 study participants who had the most arsenic in their bodies, a tolerable 16. 5 micrograms per liter of urine, had 3. 6 times the risk of developing late-onset diabetes than those in the bottom 20 percent, who had 3 micrograms per liter. Levels of arsenic were 26 percent higher in people with late-onset, or type 2, diabetes than those without the disease, the study found.
    The U. S. government sets a limit for drinking water at 10 micrograms of arsenic per liter,  which is exceeded in the water consumed by 13 million Americans who mostly live in rural areas that rely on wells to bring up ground water, the researchers wrote in the Journal of the American Medical Association. Arsenic contaminates drinking water for millions of people in Bangladesh, parts of Central Europe, Chile, Argentina and the western United States, where ground water is the source of drinking water and the land has higher concentrations of arsenic.
    Overall, 7. 8 percent of Americans are believed to have diabetes, although some do not know it. At least 90 percent of cases are the type 2 variety, in which the body loses its ability to use insulin properly. Navas-Acien said arsenic may play a significant role in diabetes incidence, but it is difficult to say how much. Arsenic can accumulate in the body, and can ruin the body’s ability to use insulin and perform the vital task of converting blood sugar into energy. Normally, insulin fits into cells via molecular doorways called receptors, which in turn signal the cell to move glucose inside, but arsenic enters the cell and somehow blocks the activity. Seafood is another source of arsenic, but the organic form found in shellfish and some fish has a carbon molecule attached and poses no risk to health, she said.
It can be inferred from the passage that the function of insulin is to______.
选项 A、digest seafood
B、change blood sugar into energy
C、accumulate arsenic in the body
D、protect the cells from arsenic
答案B
解析 推论题；从原文中，我们阅读到“Arsenic can accumulate in the body，and can ruin the body’s ability to use insulin and perform the vital task of converting blood sugar into energy”等相关信息，我们可以推论出insulin的主要任务是“task of converting blood sugar into energy”，比较阅读4个选项，B选项的表述是符合原文的含义的，是正确答案。需要考生注意的是，其他几个选项都和原文最后一段中的某个细节信息有关联，但是不符合我们题目考查的要求，不能入选。
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