How dangerous is it to use a mobile phone?
There are more than 3000 million mobile phones in use all over the world. Hence today, it is clearly the most common mode of telecommunication. Increased use has also raised concern about possible harmful effects of the radiofrequency radiation of cell phones or their base stations. In fact, mobile phones are the most important source of exposure to radiofrequency radiation. The power of mobile phones is low, at most 0.25 W but because the device is often held next to the head, the surface parts of the head to a depth of 2 cm may be exposed to a significant degree.
Exposure by mobile telephones is regulated in many countries. The Radiation and Nuclear Safety Authority (STUK) in Finland has regularly tested all mobile phones on the market, and they conform quite well to the regulations. Still in its position paper, STUK recommends that children should favour the use of text messages rather than calls, and parents should limit the number and duration of calls made by their children. In addition, the use of hands-free devices is recommended, because it reduces the head exposure significantly. All of these are merely precautionary measures, and they may be most valuable for reasons other than health concerns.
Warming of the head
In any tissue, the electromagnetic fields of radiofrequency cause a warming effect. This is similar in principle to a microwave oven. Electromagnetic and thermodynamic models suggest that the temperature increases a little on the surface of the brain. The worst-case maximum warming is about 0.2 to 0.3 °C on the brain surface and slightly more on skin surface (subjective feeling of heat is, however, mainly due to the warming of the phone and the negligible air flow between it and the ear). Physiologically this is not very meaningful, because the daily variation of temperatures in the inner parts of the body including the brain is about 0.5 °C. Moreover, a healthy young person in good condition may experience a temporary heating of even 2 to 3 °C without any harm during exercise in hot weather, to say nothing of taking a sauna bath.
It is not, however, quite certain that the temperature increase induced by radiofrequency electromagnetic fields would be quite the same as normal warming up of the tissues. In some in vitro studies, greater changes have been detected in the synthesis and activity of so called heat shock proteins than a mere temperature increase would evoke. This does not tell anything of health effects yet, and must be confirmed. Rather extensive information based on both cell culture work and population studies indicates that radio-wave fields are only harmful if they exceed by several-fold the limit values given for occupational exposures. Occupational limit values are five-fold higher than the limit values set for mobile phones.
In a Swedish study, a benign tumour in the acoustic nerve was found to be more common in those people who had used a portable phone during the past ten years. The problem is that the exposure assessment was based on questionnaires. It is typical that patients tend to remember exposures differently from control persons. Furthermore, a Danish study did not find any similar association. Exposures due to the older NMT phones were also manifold higher than the situation with the present phone models. As a whole, the evidence on acoustic tumours is not very convincing. There is no evidence of any risk for tumours of the brain. However, as people have been exposed to RF fields from mobile phones for a relatively short time and some cancers take many years to develop, further follow-up is useful to address possible risks associated with very long-term (>>10 years) exposure.
Base stations
The exposure emerging from base stations is at least one hundred times and typically ten thousand times lower than the present limit values. Nevertheless, some people feel that they experience different symptoms of malaise both around cell phones and base stations. When testing such persons, no indication has been found that there would be any direct effects on their tissues. In addition, there is no plausible hypothesis for a biophysical mechanism that could explain how such a weak field could influence living cells.
The human mind is much more powerful factor than most people believe. If one is concerned about something, it will have an effect. Thus the best explanation regarding the health effects of mobile phones is that it is all in the mind.
One level up: Here a risk, there a risk, everywhere risks, risks!
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