Radiation Types
There are two sorts of radiation: ionising and non-ionising. Ionising radiation is able to modify tissue, and is known to be dangerous. All the radio signal from mobile phones is non-ionising, and its only known effect is a small heating effect. You certainly couldn't boil an egg with it: you wouldn't even be able to appreciably warm one with the power transmitted from a mobile phone.
The fact is that although we don't know the long-term effects of using mobile phones, if there are effects they may not be related to the radio signals they use. There is a long history of using radio transmitters, both high-powered broadcast ones, and personal hand held units. Both have been used for fifty years, although hand held units used to be far more powerful than modern ones are.
There are clearly laid out safety standards for exposure to radio frequency signal levels, which set the maximum at only 20% of what is believed to be safe. Mobile phones don't even approach these limits. Standards are set by National Radiological Protection Board (NRPB) in the UK, and by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) on a global scale.
How is it monitored?
In the UK, the NRPB have statutory responsibility for monitoring radiation exposure, and the Radio Authority (RA) regularly surveys mobile phone base stations to check that the limits are not being approached.
Any risk from mobile phone use is thought to be probably related to the heating effect of the Radio Frequency (RF) signal, though various theories have been advanced that suggest other methods. To date, none of these effects have been verifiably detected.
A government report on the subject
In May 2000, the Stewart Report was published. This was a government-sponsored report that basically said There is no evidence of any risk, but recommended that a precautionary approach should be taken. The health worry identified was that people were worried about mobile phone radiation, and the worry could affect their health. The report said "drivers should be dissuaded from using either handheld or hands-free phones whilst on the move" and that masts under 15 metres high should require planning permission. The report summary is available here.
Comparative power levels
Mobile phones work at 900 MHz or 1800 MHz: broadly similar frequencies to those used for TV broadcasts. The power levels are very low indeed. The maximum power is 2 watts (900) or 1 watt (1800) but this is for very short pulses, and the maximum average power is 0.25 watt (900) or 0.125 watt (1800). Because the mobiles use power control, it is normal for them to transmit at one hundredth of the maximum, and of course only during calls whilst you are speaking or for very short bursts to keep in touch with the network.
To put this into perspective, a TV transmitter has a typical power of 2,000,000 watts, continuously for 24 hours every day.
A domestic microwave oven is permitted to emit around 10 watts at a frequency specifically chosen to heat tissues.
The big difference is that the mobile is far nearer you, and the signal level falls away rapidly with distance.
If you do the maths, it works out that using a mobile phone is probably putting about the same power into your head as a TV transmitter a few miles away. It is hard to prove a negative, but there is no good evidence to suggest that either source of radio signal is a risk to health. There are plenty of research projects in progress, but to date, the results have not been conclusive.
Phone makers are keen to make the signal avoid the user, not because it is dangerous, but because it wastes scarce battery power and reduces the handset's ability to keep in touch with the base.
See also [ Safe to Use? ] : [ Base Station Danger ] : [ Phone Shields ]
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