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THERMAL VERSUS NON-THERMAL EFFECTS frequency "carries" another signal—in this case, at 217 Hz— The whole of the debate over mobile phones and, indeed, con- which generates a regular, low-frequency pulsing effect into the cerning other sources of non-ionising radiation such as VDUs, brain. In fact, there are further subtle, harmonic pulses and fields power lines, etc., centres on the evidence for and against thermal to which the user is exposed. It is these, as well as other parame- versus non-thermal biological effects. ters of the signal, which are causing concern and are not properly A thermal, or heating, effect on tissue is currently accepted by taken into account in current guidance advice. most scientists in this area to be the only significant way by which The proposed new TETRA system, mainly for the emergency electromagnetic fields (EMFs) can pose a hazard to the body; and services, some corporate networks and the London Underground, thus all guidance, both national and international, continues to be is especially alarming in this respect, since it uses not only a 420 based on this assumption. Even the Stewart Report has not chal- MHz signal (producing a waveform that maximises radiation lenged this view. absorption for three-to-six-year-old children) but also a pulse at However, a growing body of evidence and opinion over the last 17 Hz, right in the brain's beta rhythm! This, despite a complete decade indicates that effects can lack of research on possible health occur at levels well below that at effects. which tissue begins to heat up, and that these non-thermal effects can The whole of the debate over SIGNIFICANT NEW FINDINGS pose significant risk. But before mobile phones and, indeed, It is not possible to go into great some of this is discussed, it is impor- . detail about recent research findings tant to understand how a mobile concerning other sources of (these are covered in depth in issues phone basically works. non-ionising radiation such as of Electromagnetic Hazard & The frequencies used by digital (as . Therapy), but some recent studies are opposed to the older analogue) VDUs, power lines, etc., centres significant. mobile phones (900 megahertz for on the evidence for and against In 1998, Dr Kjell-Hansson Mild at the GSM system used by Vodafone the National Institute of Working Life and Cellnet, and 1800 MHz for the thermal versus non-thermal in Umea, Sweden, reported a study of PCN system used by Orange and biological effects 11,000 users in Norway and Sweden, One2One) fall into the microwave comparing symptoms according to region of the electromagnetic duration of use of both analogue and spectrum. This frequency range, as GSM phones.* Concentrating on the well as the much lower range used by VDUs and power lines, etc., latter (since they represent 95% of phones sold), he found a sig- is termed "non-ionising" because the frequencies do not contain nificant dose-response relationship between reported symptoms sufficient energy to strip electrons from atoms. By contrast, beta (fatigue, headache, warmth behind or on ear, burning skin sensa- and gamma radiation, from nuclear fission and other sources, does tion) and duration of use, covering less than 2 minutes, 2-15 min- have enough energy to do this and is hence termed "ionising", and utes, 15-60 minutes and over | hour. For example, those Swedes it poses well-known, accepted hazards. It is partly this distinction using a phone for more than an hour were 22 times more likely to that has caused many orthodox scientists to believe that non- report an increase in warmth behind the ear than those using them ionising radiation implicitly posed little hazard, except in its for less than 2 minutes; the equivalent figure for Norwegians was capacity to heat tissue. 16-fold (see table 1). But, in the case of mobile phones, there is a further reason for These results clearly show that a heating effect does occur, concern in that the signal is "pulsed". This means that the main although how far it penetrates into the brain and whether this effect itself is responsible for all the report- ed symptoms is still unclear. Book ? Other research, also in Sweden, by Is IT...15 Professor Leif Salford at Lund University, IT SOMETHING shows that radiation at mobile phone fre- ZT SAID? quency can change the blood-brain barrier that normally allows certain chemicals to cross and keeps others out. Professor Salford observed that after only two min- utes’ exposure to mobile phone intensities, rats displayed changes in the permeability of the blood-brain barrier This is clearly a worrying finding, suggesting a non-thermal effect as has been claimed. In the USA, Professor Henry Lai and Dr = | Narandra Singh, at the University of —— Washington in Seattle, reported increased L< : strand breaks in DNA in rats' brains after J rats were exposed to mobile phone frequen- €el —Y cies,’ although some researchers are claim- ing not to be able to replicate the effect. Meanwhile, in the UK, Dr Alan Preece at Bristol University reported in April that he ° \ sy 18 = NEXUS THERMAL VERSUS NON-THERMAL EFFECTS The whole of the debate over thermal versus non-thermal biological effects. DECEMBER 2000 — JANUARY 2001