A media frenzy surrounded the "mobile phones are good for you" study and the recent BBC Panorama, featuring the research with a negative spin. The reality is that Dr Alan Preece's long awaited research at Bristol University on the effects of mobile phone radiation on cognitive function published on April 8 proved to be something of a damp squid.

This was mainly due to the pathetically inadequate funding (£3000) from the Department of Health (DoH), which only allowed him to carry out two exposure tests of 25 to 30 minutes each, with two groups of 18 subjects. Both groups were exposed to either a simulated analogue or a digital mobile phone signal at 915 MHz, or no signal at all, and then tested on 15 different cognitive tests.

The only significant finding, for both groups, was a 4 per cent decrease in reaction time on a choice reaction test, which was more pronounced for the analogue exposure than the digital.

Different press reports interpreted this as everything from a beneficial effect to a hazard.

In fact, the result may simply reflect the effect of the very brief exposure time and may disappear or reverse with prolonged exposure in the same way that alcohol in small doses is a stimulant, but in large quantities is a depressant.

Despite previous media misreporting, Preece did not observe any short term memory loss (Int J Radia Biol, 1999; 75: 447-56).

The small number of subjects and and the limitation of exposure time are obvious flaws in the study, so finding a statistically robust effect with such brief exposure is worrying especially since it could indicate a non thermal effect, a possibility that both the National Radiological Protection Board (NRPB) and industry currently deny.

Preece suggests that it might have been produced by a heating effect, as the temperature in the head has been estimated to rise between 0.5 to 2 ¡C over 30 minutes when exposed to a mobile phone.

But once the blood flow through the head is taken into account, a temperature rise is very small indeed ranging from 0.01 to 0.1 ¡C. The NRPB generally considers a thermal effect to be one that raises the temperature by at least 1 ¡C.

However, if one takes account the enhancement effect of metal specifically, amalgam and other metal fillings, earrings and eyeglasses (especially the metal rimmed variety) the amount of absorption of waves could be considerably increased, causing "hot spots" on the head easily above the NRPB's thermal guidance. This is a possibility that researchers have completely ignored to date.

But from this experiment, no useful conclusion can be made, mainly because Dr Preece did not receive enough funding to use the complete pulsing characteristics of a standard digital phone.

The real story missed by the media, and the key factor which Preece's research and that of others does not address is this low frequency pulsing, which a growing number of independent researchers believe is a main cause of health problems.

Pulsing effects occur below the level of heating and are generally denied by the NRPB and the industry. The non thermal effects produced by the low frequency pulsing is what many researchers believe to be one of the principle ways, for instance, that mobile phone radiation can affect brain function.

Based on previous research notably Prof Ross Adey's findings in the US on magnetic fields producing calcium ion influx in the brain this frequency might produce other cognitive effects. In 1994, Prof Salford in Sweden found changes in the permeability of the blood brain barrier at levels as low as 0.016 watts per kg which is well below the level of heating.

Recent work by Adey's long time colleague, Dr Carl Blackman, has also shown an effect of magnetic fields on apoptosis programmed cell death.

It is important that any further research the DoH decides to support is underwritten by enough funds to ensure some meaningful results for the 14 million Britons who currently use a mobile phone every day.

Instead of a paltry £3000, it should provide something nearer to the £113,000 it was able to find for research at Porton Down's secret military research laboratory on learning deficits and changes in brain physiology in rats the results of which will doubtless never be fully disclosed.

In the meantime, to reduce your exposure, when you dial a number, wait until it has connected before putting the phone to your head. While it is searching to contact a base station, the phone is operating at maximum strength 2 watts.

Only once it connects does it "power down" to about a hundredth (0.02w) of this level. By holding it away from the head for the four to five seconds before it connects you will avoid taking a four to five second 2 watt "hit" to your brain each time you ring, with possibly 10 "hits" a day.

If you are in a good reception area, the phone should automatically "power down". However, in a bad area, it will stay at near maximum strength of 2 watts. So when calling (or receiving) in a bad reception area, keep the call as quick as possible.

Finally, consider getting a shield or remote earpiece to cut radiation remember you are talking about a lifetime's cumulative exposure.

!ASimon Best