首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Can electricity cause cancer? In a society that literally runs on electric power, the very idea seems preposterous. But for more
Can electricity cause cancer? In a society that literally runs on electric power, the very idea seems preposterous. But for more
admin
2011-02-10
44
问题
Can electricity cause cancer? In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields, which are generated by everything electrical, from power lines and antennas to personal computers and micro-wave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate or the worst kind of paranoia.
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 causal 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 lose 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, it 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 far 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.
The main idea of this passage is ______.
选项
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 cancer
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/HkcO777K
本试题收录于:
NAETI中级口译笔试题库外语翻译证书(NAETI)分类
0
NAETI中级口译笔试
外语翻译证书(NAETI)
相关试题推荐
Professionalsinvolvinginsuchdevelopmentshouldhaveauniquesenseofinnovation,theabilitytoassimilatenewinformation,
OneofFreud’sgreat______intothehumanpersonalitywasthediscoveryofhowitisinfluencedbyunconsciousprocesses.
Allofusinresearchhavefocusedonadrugthatisso______thatitcanchangebrainchemistry.
ItisrumoredthatMr.Smith,thegrandsonofthefounderoftheuniversityandaprofessorofphilosophy,willbe______aspresi
Japanandthenewlyindustrializedcountriesarepassinglabor-intensivesectsasgarment-makingovertolessdevelopednations
Wearenotconsciousoftheextentofwhichworkprovidesthepsychologicalsatisfactionthatcanmakethedifferencebetweena
Whattheseyoungmenandwomenneedtodonowistodevelopamentalitytoreconciletheiridealswithreality.
Somecorruptedofficialstheworldover,whatevercrimestheyhavecommitted,canalwaysgetawaywith______.
Theprisonguardswerearmedandreadytoshootif______inanyway.
JohnCramer,aresearcherattheUniversityofWashington,hascreatedtwodifferentexpositionsofwhatthebigbangmighthave
随机试题
象皮腿曲氏试验I
冠桩的长度一般为根长的可保留的牙齿其牙槽骨吸收不能超过根长的
明确提出“法治应当优于一人之治”的学者是:()。
债券的偿还期限一般分为()。
下列选项在性质上属于政府综合统计机构的包括()
计算净资本,要求证券公司保持充足、易于变现的流动性资产,可以满足紧急需要并抵御潜在的()。
下列各项中,企业应确认为无形资产的有()。
智化寺的“京音乐”的价值?
简述南京国民政府诉讼审判制度的特点。
设f(x)在[0,1]上满足f"(x)>0,则f’(0),f’(1),f(1)-f(0)或f(0)-f(1)的大小顺序为()。
最新回复
(
0
)