研究生科技英语阅读答案6.doc

Unit 6 Are Cell Phones Safe? I. comprehension and Appreciation 1. Are you a cell phone user? How long do you talk on it per day? 2. Why is there a controversy as to the safety of using cell phones? What should we do according to the experts? Some studies have suggested that frequent use of cell phones causes increased risk of brain and mouth cancers, others have found no such links. But since cell phones are relatively new and brain cancers grow slowly, many experts are now recommending taking steps to reduce exposure. 3. Why are cell phone users able to choose and interpret the results of using cell phones they prefer and ignore the ones they don’t? With some 4 to 5 billion cell phones now in use worldwide and hundreds of studies seeking evidence of their health effects published in peer-reviewed journals over the last 10 years, there’s precious little scientific certainty over whether cell phones pose any danger to those using them. For nearly every study that reports an effect, another, just as carefully conducted, finds none. 4. Why is it difficult to assess the effects of cell phones? The effects of cell phones have proven difficult to assess because they are relatively new, the way and the amount they’re used continues to evolve, and the problems that cell phones might cause are hard to detect. 5. What kind of radiation do cell phones produce? Is there any potential damage to DNA? Cell phones produce “non-ionizing” radiation, which, unlike X- or gamma rays, doesn’t damage DNA by stripping away electrons from molecules in cell tissue. Radiofrequency energy does, however, produce heat and, at high enough levels, can damage cell tissue.6. Both the U.S. FCC and the ICNIRP in Europe set some limits on cell phones’ SAR, is there still some question remained? It is true that the U.S. FCC and the ICNIRP in Europe set some limits on cell phones’ SAR — the measure of the amount of radiofrequency energy a cell phone user absorbs — at, respectively, 1.6 and 2.0 watts pe