Biological Effects of Radiofrequency Electromagnetic Field

Radiofrequency electromagnetic field=radiation (RFR) covers a large segment of the electromagnetic spectrum and falls within the nonionizing bands. Its frequency ranges between 3KHz and 300GHz. Cellular phones, wireless transmission towers for radio, TV, and telecommunication, radar and many other applications emit RFR. Different frequencies of RFR are used in different applications. For example, the frequency range of 540–1600KHz is used in AM radio transmission, while 76–108MHz is used for FM radio. Cell phone technology uses frequencies mainly between 800MHz and 3GHz, and RFR of 2450MHz is used in microwave cooking. Because of the proliferation of wireless communication in recent years, a large population of people is exposed to RFR constantly. There are two major concerns on the possible biological=health effects of RFR: the effect of RFR absorbed during cell phone use and the exposure to RFR emitted from transmission towers. These two situations represent very different exposure conditions. The close proximity of a cell telephone antenna to the user’s head leads to the deposition of a relatively large amount of radiofrequency energy in the head.The relatively fixedposition of the antenna relative to the head causes a repeated irradiation of a more or less fixed amount of body tissue. Exposure to RFR from cell phones is of a short-term, repeated nature at a relatively high intensity, whereas exposure to RFR emitted from transmission towers is of long duration but at a very low intensity and, in general, the whole body of a person is exposed. Biological effects of RFR depend on how energy is deposited in the exposed organism. There are three major physical parameters: frequency, intensity, and duration of exposure. To understand the possible health effects of exposure to RFR, one needs first to understand the effects of these different parameters and how they interact with each other. These are discussed in this entry.