| Hold the Phone |
| Wednesday, 26 April 2006 | |
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Gemma Simpson explores the myths and realities of mobile phone use You probably use one every day, but is it putting your health at risk? There are rumours that your mobile could be frying your brain with every call, that children living near mobile masts have an increased risk of cancer and, sorry boys, that leaving your mobile in your trouser pocket could be damaging your vital organs.  Credit: Equinox Graphics The problem in determining whether mobile phones are a risk to health lies in the difficulty of simulating and replicating conditions in which they are used. Add to this the fact that mobile phones have only been in use for the past decade, and finding the long-term effects becomes even more complicated. So what are we worrying about? One of the most notorious links is that using a mobile phone might increase one’s risk of developing a brain tumour and many studies are looking into this possibility. But so far, the evidence suggests that mobile phone use is not putting your health at risk. The Interphone study is an international project coordinated by the European Union and the International Union Against Cancer, involving some 13 countries.The study has been examining data from 1998 onwards to ascertain whether there is a link between brain tumours and regular mobile phone use. Last month British researchers issued their findings as part of the Interphone study and suggested that regular mobile phone users were at no greater risk of developing brain tumours than less frequent users. Another worrying hypothesis is that the radiation emitted from mobiles can cause DNA strands to break and genotoxic effects to occur.These effects cause genetic mutation and might contribute to the development of tumours. An earlier international study called REFLEX suggested that radiation coming from your mobile phone could damage the DNA in cells. The original study involved 12 groups from seven European countries, all supposedly carrying out identical experiments. But experts believe the results were far from conclusive as the different groups were not completely standardised due to financial constraints. The study found that animal and human cells exposed to electromagnetic fields showed a significant increase in DNA damage that could not always be repaired by cell repair mechanisms. This genotoxic effect was observed in some cell lines, but not in others. “In my opinion, the results are rather unusual for a genotoxic agent and might be due to an indirect effect,” states Professor Guenter Speit, who is currently trying to replicate the REFLEX findings. Since REFLEX, many other groups have been trying determine whether or not our DNA really is deteriorating with every phone call we make.The good news is that no one seems able to find evidence of disintegrating DNA. Professor Guenter Speit and his colleagues at the University of Ulm in Germany have, thus far, been unable to find conclusive evidence that genotoxic effects are occurring.“At present the problem of the conflicting results is not solved,” states Professor Speit. The team is currently working with Professor Rüdiger, of the original REFLEX study, in Vienna, to try and solve this prickly problem. Does you ear feel warm after a call? Don’t worry; this is probably just due to the battery heating up as the phone is used. But there is some concern that microwave radiation emitted from a mobile phone might be causing heating effects that are less favourable inside the body. High intensity microwave fields are well known for their ability to heat up biological materials—this is how a microwave oven works. For temperature increases above 1°C damaging thermal effects will occur, but there is a grey area for temperature changes around 0.5°C. Mobile phones are low intensity microwave sources and only cause increases in temperature between 0.1°C and 0.3°C.“These small temperature differences are generally dismissed as insignificant, and any apparent effects of exposure are described as ‘non-thermal’,” states Dr David de Pomerai of the University of Nottingham. Dr de Pomerai was the first to credibly report that microwave heating could possibly induce cells to produce heat shock proteins, another genotoxic effect. But even his results have turned out not to be what they originally seemed. “Unfortunately, our ‘convincing’work on microwave radiation causing cellular damage turns out to have been a rather subtle thermal artefact… [that] undermines any effect of microwave fields whatsoever,” states Dr de Pomerai. Other researchers think that it might be possible that ‘hotspots’ are forming in the brain’s tissue. Although it seems pretty unlikely, researchers at the Mobile Telecommunications and Health Research Programme (MTHR) are currently investigating the possibility. But even if low levels of radiation from mobile phones can damage DNA, does it actually make a difference to your health? Research suggests that it does not. But for a better idea of what exactly is going on we need the remaining Interphone study results.As one of the largest studies on brain tumours ever performed it is hoped that the Interphone study will at last provide some conclusive results on mobile phone safety. The study’s conclusions should be released in the next couple of months. As both research efforts and bickering amongst scientists continue, there is hope that a massive international study, organized by the World Health Organisation, will help answer queries about the potential health hazards of mobile phones.The study is due to begin this year and will monitor around 200,000 mobile phone users, both infrequent and frequent, hopefully for the rest of their lives.What makes this study different is that, unlike Interphone and other studies, it does not rely on the human subjects having to remember their mobile phone use.With memories being prone to bias, it is hoped this study will give more representative results. Unfortunately, it could be years before results emerge. One of the real concerns is that children are at more risk from the adverse health effects of using mobile phones. A child’s brain is still developing and their skull is thinner, so radiation produced by a mobile phone handset can penetrate with more ease.Additionally, if they start using mobile phones at an early age then their cumulative lifetime use will be higher than for new adult users.“Chronic diseases such as cancer have a long latency period,” states Professor Franz Adlkofer, who was involved with the original Interphone study.“While adult people may die before the outbreak of the disease, this may not be the case with children.” Consequently, children are advised to use mobile phones only in an emergency. Advice from the MTHR recommends that children under nine years of age should not be given a mobile phone at all. But what about mobile phone masts; do the children living nearby really have an increased chance of cancer? Not necessarily. A mobile mast is intended to serve areas that are at least 50 metres away. Therefore if you do live very close to a mast the powerful main beam will just pass directly over your head. If you live within 50–200 metres away then you may be exposed to the beam, but the intensity of the radiation will be greatly reduced. “I fail to see how the much lower exposures from mobile phone masts (usually 0.1–1.0% of the dose received from a handset) could possibly be causing the wide range of adverse health effects that anti-mast campaigners claim,” states Dr de Pomerai. Although conclusive evidence has not yet been produced it seems that the telecommunications companies are concerned. The mobile phone industry has spent millions on investigating the safety of their handsets and it is still resolute that there is no link between the use of mobile phones and any adverse health effects. It seems that no one can make up their mind about whether the mobile phone really is a threat to health. “Uncertainty is the major concern,” comments Professor Adlkofer. “We do not know much about the effects of mobile phone radiation and whether they might constitute a risk to the health of people or not. The actual problem is that no scientist is at present in the situation to exclude such a risk with certainty.” So what do you think about mobile phones? A fantastic advancing technology, or an unknown danger to our health? “Reluctantly I’m coming to the conclusion that this is a huge non-issue, generating far more hot air than light in the process,” states Dr de Pomerai.Most other experts seem inclined to agree. “Nobody can predict the future. Findings from studies have been reviewed together by expert committees and these reviews concluded generally that there is no evidence for risk to date,” states Dr Minouk Schoemaker, of the Institute of Cancer Research, who is heading the British part of the Interphone study. “Longer-term studies are needed… [and] it is important that all evidence is reviewed when evaluating health risks of mobile phones, rather than selectively focusing on a few studies.” With mobile phone sales continuing to rise, it seems most people consider the benefits of using a mobile outweigh any potential health hazards.And by the time we know if there is a health risk, will any of us be able to cope without our mobile phones? Gemma Simpson is a PhD student in the Cavendish Laboratory
References and ResourcesAnswering the cell phone debate, New Scientist Mobile ‘don’t raise cancer risk’, BBC News Q&A: Mobile phone safety, BBC News How cell phones work, howstuffworks.com Phone radiation may push cells around, New Scientist ‘Conclusive’ study of cell phones fuels controversy, New Scientist Schoemaker, M.J. et. al., Mobile phone use and risk of acoustic neuroma: results of the Interphone case-control study in five North European countries. British Journal of Cancer, 93, 842-848 (2005) Quotes and other information from interviews/ correspondence with: |
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