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
2017-06-11
61
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 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, 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 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.
The view-point of the EPA is______
选项
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.
答案
A
解析
由文章第二段第三句,环保署目前的结论是据科学证据指出极低频电磁场——具有长波的电磁场——和白血病,淋巴瘤及脑癌之间有着难以确定的联系,因此电和致癌有一定难以确定的关系。故选A。
转载请注明原文地址:https://kaotiyun.com/show/ryFO777K
0
考博英语
相关试题推荐
Insteadofbeingsituatedatafixedcampus,theCityUniversityconductsclassesatvarioussitesdeemedconvenienttostudents.
TheBushcrowdbristlesattheuseofthe"Q-word"—quagmire(沼泽)—todescribeAmericaninvolvementinIraq.Butwithoursoldiers
Educationaldevelopmentisboundupwitheconomicprogress.
Theimagewasriveting,asjusticeJohnPaulStevens,aChicagonative,presentedit.Agangmemberandhisfatherarehangingo
FoodanddrinkplayamajorroleinChristmascelebrationsinmostcountries,butinfewmoresothaninMexico.Manyfamiliesov
EdithSmithofNewYorkwasconcernedabouther18-month-olddaughter,Amanda.Thedaughterdidnotrespondwhenherparentsspok
Everyoneitseemshasahealthproblem.AfterpouringbillionsintotheNationalHealthService,Britishpeoplemoanaboutdirty
Thegoalistousecrops,weedsandevenanimalwaste______thepetroleumthatfuelsmuchofAmericanmanufacturing.
EvenbyDavidCameron’sstandards,itwasaswiftU-turn.Firstthingyesterday,DowningStreetwasstillrefusingtopublisha
Whatdotheextraordinarilysuccessfulcompanieshaveincommon?Tofindout,welookedforoperations.Weknowthatcorrelation
随机试题
A型超声提供的信息
患者,男性,75岁。确诊COPD已10多年,本次因COPD急性加重2天急诊入院。查血气分析(刚吸氧约15分钟)示:pH7.32,PaO249mmHg,PaCO272mmHg,AB35mmol/L,BE+16mmol/L。目前患者病情稳定,准备出院,医生
下列关于DR较CR更具优点的描述中不正确的是
某市技术监督局在抽查本市市场上的饮料时发现,除三种名牌饮料外,其余饮料均不合格,该局在当地新闻媒体上对检查结果进行了详细介绍,导致一些厂家生产的饮料销量急剧下降。下列说法中正确的是( )。
企业应当按照与重组有关的直接支出确定预计负债的金额,这些直接支出包括留用职工岗前培训、市场推广、新系统和营销网络投入等。()
作为研究者的教师在教育教学活动的自然状态下,根据研究的问题进行有目的、有计划的看、思、记,这种方法叫作()。
根据以下资料,回答下列题。2011年全国批准建设用地61.2万公顷,其中转为建设用地的农用地41.05万公顷,转为建设用地的耕地25.3万公顷,同比分别增长13.5%、14.8%、8.5%。2010年转为建设用地的农用地占批准建设用地的比重
新时代党的建设伟大工程,要结合伟大斗争、伟大事业、伟大梦想的实践来进行,以政治建设为统领,全面推进党的政治建设、思想建设、组织建设、作风建设、纪律建设,把制度建设贯穿其中,推动全面从严治党向纵深发展。推动全面从严治党向纵深发展,需要
软件设计包括软件的结构、数据接口和过程设计,其中软件的过程设计是指______。
A、Intherestaurant.B、Inahotel.C、Inasupermarket.D、Inashoppingmall.B
最新回复
(
0
)