Radio signals for the next generation of mobile phone services can cause hea

游客2023-10-09  22

问题     Radio signals for the next generation of mobile phone services can cause headaches.
    A study was carried out recently by the Dutch Technological Research Institute. The study was the first to look for the impact of mobile phones on health. It was also the first study to find a significant negative impact from 3G base stations, which is set up for fast data transfer. Fast data transfer will enable services such as video conferencing on a mobile device.
    The study compared the impact of radiation(辐射) from base stations used for the current second generation mobile telephone network with that of base stations for the third generation (3G) networks.
    A base station, which usually covers a "cell" area of several square kilometers (miles), transmits(传播) signals to mobile phones with an electromagnetic field(点磁场)。
    If the test group was exposed to third generation base station signals, there was a significant impact. They got headaches and felt nauseous.
    There was no negative impact from signals for current mobile networks.
    Follow-up research was needed to confirm the findings as well as to look at any long-term health effects and biological causes.
    The double-blind laboratory tests—meaning no one in the survey knew if a 3G-like base station was actually transmitting signals—exposed test subjects to expected level of average radiation for 3G networks.
    Existing research gives no scientific evidence that second—generation phones cause cancer while a long-term study by the International Agency on Research on Cancer is not expected to give results before 2004.

选项 A、do not receive signals transmitted with an electromagnetic field
B、can receive signals from a larger area than 3G mobile phone
C、cause worse impact when they are used close to the head
D、have no negative impact on human health

答案 D

解析
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