I've hopefully debunked a lot of pseudoscientific myths over the years, I've even done it in the pages of Materials Today with an item on the nonsense that is cold fusion. Another issue that needs debunking is the notion that using a mobile phone (cellphone) will somehow fry your brain. I've covered that topic in my new book Deceived Wisdom (http://sciencebase.com/dw).

The World Health Organization (WHO) has classified the cellphone as a possible carcinogen, adopting as ever, the precautionary principle. But, just because someone takes precautions doesn't mean there was ever an issue in the first place. There is no evidence of anyone frying their brain with a cellphone or even increasing their risk of brain cancer however marginally. A physicist friend in Canada was musing on a possible mechanism through which electromagnetic fields from an active cellphone might somehow have a biochemical effect.

Cellphones don't deal in the kind of ionising radiation that is often associated with tissue damage and increased cancer risk. There are no X-rays nor gamma rays to sever chemical bonds and disrupt DNA. But, is it possible that certain wavelengths of non-ionizing radiation could nevertheless split bonds and so increase the risk of cancer ever so slightly? After all, during mitotic cell replication, during the copying of DNA and new chromosome construction bonds are being broken and re-made all the time, generally catalysed by enzymes and fuelled by ATP, adenosine triphosphate with no radiation being necessary. During this process, could radiation energy transfer to the DNA (e.g. through resonant heating) and so damage the DNA. If that could occur and the damage was not repaired by enzymes or didn't kill the cell outright then it might just be possible that uncontrolled cell replication might result from a mutation that occurred.

It should be pointed out that random DNA mutations occur all the time because of natural reactive species in our bodies and cosmic rays pounding us constantly. But, might electromagnetic radiation of a particular wavelength allow DNA fragments to re-orient and/or migrate too quickly if the energy transfer is resonant for a particular molecule and so lead to damage? If evidence were found for such a hypothesis then it might suggest that children (and fast-growing tissues in adults) would be more vulnerable than slow-reproducing tissues. So, what might those wavelengths or frequencies be?

The water molecule has a strong resonance at 2.45 GHz, which is why microwave ovens use this frequency and very high power to great effect in spinning up the water molecules and leading to a heating effect is that excitation is lost as vibration, heat, to surrounding "food" molecules. DNA, RNA, and protein fragments are much bigger entities than water molecules and so any effect would be at lower frequencies although whether they would be microwave/rotationally active is a different matter, if they were susceptible the frequencies might lie between a few MHz and a few hundred MHz. The 50 or 60 Hz frequencies of mains electricity would have no appreciable effect except at extremely high field strengths.

Frequency and field strength must be taken into account, however. Microwave ovens are obviously made to be powerful so that they can heat and cook food. They radiate at about 1 kilowatt in confined space. Broadcast radio transmitters emit at 10s or even 100s of kilowatts but by the time such emissions reach the audience they are very weak at the order of microwatts or even nanowatts. Cellphone transmitters fall somewhere in between perhaps producing bursts of power at around 1 Watt. Road traffic officers using speed trap radar guns might have more to worry about than cellphone users as those devices have higher transmission power. And anyone standing in front of an air traffic control radar system should get out of its way as quickly as possible.

David de Pomerai of the University of Nottingham offered some additional insights, "The power from a cellphone mast falls off roughly as the square of the distance, and since the beam is directed outwards rather than downwards the very safest place to be is right underneath the mast!" he explains. The actual microwave fields encountered in urban areas where there are lots of transmitters, but also reflections off buildings are of the order of microwatts and certainly no more than a milliwatt.

In order to find evidence for any of the putative health effects of all this chemistry and physics with respect to cellphones, we will have to study a large population over many years and compare the rates of cancer originating in the head among regular cellphone users and non-users (if we can find any of the latter). De Pomerai adds that, some research claims to see effects (although it is usually rather marginal) while others studies reveal no changes whatsoever.  "The whole field is extremely messy, with no one taking the trouble to replicate (exactly) any positive effects reported," he says. "Instead, different groups use dozens of test systems (different organisms, cell lines, frequencies, field strengths and exposure equipment), so it's hardly surprising that the overall picture is confused."

De Pomerai's own team began their work about 12 years ago with what looked like a robust and reproducible effect but once they had calibrated their exposure equipment it revealed a very slight (just 0.2 degrees Celsius) extraneous heating effect when the field was switched on. They took steps to minimise this heating and the whole putatively detrimental effect they thought they had found disappeared.

"I don't think many people have looked with sufficient care for other possible explanations of apparently positive findings," De Pomerai adds.
"Many, I suspect (but perhaps not all), would evaporate if subjected to really close scrutiny." The radiation risks due to flying, medical X-rays and the general background radiation are all fairly well established and reproducible in a way that exposure to cellphones is not. It could be that worrying about the minuscule bursts of non-ionising radiation from a cellphone is akin to someone on the Titanic worrying about splashing water on the floor while taking a bath in their cabin.

David Bradley blogs at http://www.sciencebase.com and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".