Now the alarmists have gained some qualified support from the U.S. Environmental Protection Agency. In the executive summary of a new scientific review, released in draft form late last week, the EPA has put forward what amounts to the most serious government warning to date. The agency tentatively concludes that scientific evidence"suggests a casual link" between extremely low-frequency electromagnetic fields—those having very longwave-lengths—and leukemia, lymphoma and brain cancer, While the report falls short of classifying ELF fields as probable carcinogens, it does identify the common 60-hertz magnetic field as "a possible, but not proven, cause of cancer in humans."
The report is no reason to panic—or even to lost sleep. If there is a cancer risk, it is a small one. The evidence is still so controversial that the draft stirred a great deal of debate within the Bush Administration, and the EPA released it over strong objections from the Pentagon and the White House. But now no one can deny that the issue must be taken seriously and that much more research is needed.
At the heart of the debate is a simple and well-understood physical phenomenon: When an electric current passes through a wire, tit generates an electromagnetic field that exerts forces on surrounding objects, For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak. The ELF magnetic field generated by a video terminal measures only a few milligauss, or about one-hundredth the strength of the earth's own magnetic field, The electric fields surrounding a power line can be as high as 10 kilovolts per meter, but the corresponding field induced in human cells will be only about 1 millivolt per meter. This is far less than the electric fields that the cells themselves generate.
How could such minuscule forces pose a health danger? The consensus used to be that they could not, and for decades scientists concentrated on more powerful kinds of radiation, like X-rays, that pack sufficient wallop to knock electrons out of the molecules that make up the human body. Such "ionizing" radiations have been clearly linked to increased cancer risks and there are regulations to control emissions.
But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect. Though there is a body of laboratory work showing that exposure to ELF fields can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found.
The Pentagon is for from persuaded. In a blistering 33-page critique of the EPA report, Air Force scientists charge its authors with having "biased the entire document" toward proving a link. "Our reviewers are convinced that there is no suggestion that (electromagnetic fields) present in the environment induce or promote cancer," the Air Force concludes. " It is astonishing that the EPA would lend its imprimatur on this report." Then Pentagon's concern is understandable. There is hardly a unit of the modern military that does not depend on the heavy use of some kind of electronic equipment, from huge ground-based radar towers to the defense systems built into every warship and plane.
1. The main idea of this passage is
[A]. studies on the cause of cancer
[B]. controversial view-points in the cause of cancer
[C]. the relationship between electricity and cancer.
[D]. different ideas about the effect of electricity on caner.
2. The view-point of the EPA is
[A]. there is casual link between electricity and cancer.
[B]. electricity really affects cancer.
[C]. controversial.
[D].low frequency electromagnetic field is a possible cause of cancer
3. Why did the Pentagon and Whit House object to the release of the report? Because
[A]. it may stir a great deal of debate among the Bush Administration.
[B]. every unit of the modern military has depended on the heavy use of some kind of electronic equipment.
[C]. the Pentagon's concern was understandable.
[D]. they had different arguments.
4. It can be inferred from physical phenomenon
[A]. the force of the electromagnetic field is too weak to be harmful.
[B]. the force of the electromagnetic field is weaker than the electric field that the cells generate.
[C]. electromagnetic field may affect health.
[D]. only more powerful radiation can knock electron out of human body.
5. What do you think ordinary citizens may do after reading the different arguments?
[A].They are indifferent. [B]. They are worried very much.
[C]. The may exercise prudent avoidance. [C]. They are shocked.
答案詳解：
1. D 電力對癌癥影響的不同觀點。文章一開始就提出了“電會致癌嗎?”這個問題。十多年來，一大批科學(xué)家和新聞界人士都指出：研究結(jié)果似乎表示：接觸電磁場可能會增加患白血病和其他惡性腫瘤的危險性。所以說到目前為止還難以確定電力對健康的影響究竟是理性的，還是杞人憂天。見難句注釋1。第二段公布了環(huán)保署的報告，見難句注釋3。第三段說明：即使有致癌危險也是極微的。但應(yīng)予以認(rèn)真對待，進行更多的研究。而第七段中空軍方面的科學(xué)家還沒有被說服(見難句注釋9)，明確提出，我們的評論員認(rèn)為沒有跡象說明環(huán)境中存在的電力會誘發(fā)或促發(fā)癌癥。A. 對致癌因素的研究。 B. 致癌原因方面有爭議的觀點，這兩項根本部隊，和文內(nèi)電力毫無關(guān)系。C. 電力和癌癥的關(guān)系，文中涉及的是電力究竟會不會致癌的兩種觀點，而不是兩者之關(guān)系。
2. A. 電和致癌有一定難以確定的關(guān)系。答案在第二段第三句，環(huán)保署目前的結(jié)論是據(jù)科學(xué)證據(jù)指出極低頻電磁場——具有長波的電磁場——和白血病，淋巴瘤及腦癌之間有著難以確定的聯(lián)系，見難句注釋3。A. 電確實致癌，不對。 C. 有爭議的。說的不夠清楚，爭議什么。 D. 低頻磁場是一個可能致癌因素。這只是論點的一面。
3. B. 現(xiàn)代軍事的任何部門都一直依賴于應(yīng)用大量應(yīng)用電子設(shè)備。五角大樓和白宮所以反對環(huán)保署公布報告之理由就在此?？哲姺矫娴膶＜宜哉f環(huán)保署方面的報告“歪曲了整個文件以證明兩者之間的關(guān)系”也在此。見難句注釋4。所以文內(nèi)說“角大樓的關(guān)注是可以理解的。”A. 報告會在布什政府內(nèi)引起大規(guī)模的辯論，這是結(jié)果。 C. 五角大樓的關(guān)注是可以理解的，這不是原因。 D. 他們有不同的觀點。
4.A. 磁場力太弱不會產(chǎn)生有害作用。答案在第四段第二，三句，當(dāng)電流通過電纜，產(chǎn)生磁場，對周圍物體產(chǎn)生(影響)力。許多年來，科學(xué)家把任何有關(guān)“這些力可能有害的想法”置于一邊(不予考慮)，主要是因為它們(所產(chǎn)生的力)非常弱。B. 磁場力比細胞產(chǎn)生的電磁場弱。只是明確指出的事實。 C. 磁場力對人的健康有害。不對。 D. 只有更強的輻射才能把人體中的電子擊出來。不對。
5. C. 他們會采取謹(jǐn)慎小心避開電器的途徑。因為他們不可能象A項那樣漠不關(guān)心。這種問題直接影響人的生命。B. 他們非常擔(dān)憂。 D. 他們感到震驚，這兩項都不可能，因為還在爭議中，唯一的途徑是盡量避開和電器接觸。
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