Mobile phone danger seems to be a perennial story in the media. I got my first mobile phone before the world wide web had been invented, but I am sure that there must have been people running off fliers on their Roneo machines warning of the dangers and then attaching them to lamp posts with sticky tape. It is a subset of the general electromagnetic radiation scare story and has itself two components - radiation from the phones themselves and radiation from the towers.
Let's start off by looking at how the spectrum of electromagnetic radiation is made up. Shorter wavelengths mean higher energy and it is generally accepted that cancer caused by DNA disruption requires wavelengths less than that of visible light. Above ultra-violet the photons simply do not possess the necessary energy.
People worried about electromagnetic radiation seem to be quite happy with the visible part of the spectrum, although it is always a nice joke to ask the most strident "we don't need any EMF here" campaigners if they really are opposed to all wavelengths and frequencies. If you are feeling particularly spiteful you can point out that the usually harmless chemical dihydrogen monoxide can become dangerous if exposed to enough radiation at wavelengths just longer than visible light. That same radiation can also cause nasty burns on your feet if you go to sleep in front of the radiator. ("Radiator"! The name alone should be a warning.)
Above visible light there seem to be several spectrum bands which cause concern. Quite rightly nobody seems too worried by the television and broadcast radio signals which fill the air around us. While they might be pushed out by quite high-powered transmitters there doesn't seem to be any incentive for scaremongers to frighten people, or perhaps they realise that arguing for the elimination of television might be a hard sell.
The things that cause concern are microwaves, low-frequency emissions from power lines, low-power communication such as WiFi and Bluetooth, and the big one, mobile phones.
There is good reason for non-scientists to fear microwaves, because everyone has seen how a microwave oven heats things quickly and has mandatory safety features to keep the waves inside. Most people, however, are happy to accept that the radiation stays inside the oven (even if they don't understand how this is achieved), so, like television and radio, it would be a very hard sell to get people to give up the convenience.
The power line problem is another perennial but it seems to be quiet at the moment. Maybe the explanation behind the headline "Rare cancer in children doubled near power lines" when the rate has gone from 1 per million to 2 per million because one more case has occurred has finally got through to the journalists who report these scares. Or perhaps people really do like to have the lights on and be able to eat microwaved food in front of the television and are prepared to accept the risk from the wires.
The WiFi and Bluetooth scares seem to usually involve some school administration which has refused to have a wireless network installed because of threats of legal action by parents if the kids ever show signs of not growing up geniuses. Again, this seems to be a quiescent problem at present, maybe because the almost ubiquity of home wireless networks has educated people to the fact that convenience outweighs the risk.
That leaves mobile phones, and as I said above, this means two types of problems - towers and handsets.
Opposition to towers is relatively easy to understand. They look like something out of a science fiction movie and they obviously push out a powerful signal because they need large power supplies Yes, they are quite powerful transmitters, but to put yourself at risk you would have to climb up and put your head right in front of one of the directional antennas, and even then your biggest risk would come from falling off.
Apparently there are more mobile handsets in Australia than people, so if there is any problem with them then it has the potential to be a very big problem indeed. The facts are, however, that the power of an individual handset is very low (your microwave oven puts out about 4,000 times as much power) and the wavelength of the radiation means that it cannot destroy DNA or the cells around it. (The latter also applies to the towers.) The number of handsets in use around the world, the decades over which the phones have been in use, and the apparently almost unmeasurable rate of problems like brain cancers which can indisputably be blamed on the phones should be enough to make people feel safe using them. Until the next scare story in the paper comes along.
This article was published as the Naked Skeptic column in the July/August 2011 edition of Australasian Science