We love our mobiles... but are we being told all the facts about how safe they are?
They are both fashion accessories and an essential part of our lives. Yet since they first became widely available in the 1990s, there have been nagging doubts about just how safe they are.
Could they cause cancers in the brain? Does living near a mobile phone mast raise your risk of other cancers? Despite official reassurances, we still don't seem to be any closer to a definite answer.
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Dangerous call? Opinion is divided on the safety of mobile phones
Last September, the Mobile Telecommunications and Health Research (MTHR) programme, which is funded jointly by the Government and the industry, concluded that mobile phones, base stations and masts "have not been found to be associated with any biological or adverse health effects".
This conclusion was based on the findings of the working of the cells in our bodies. A major UK report eight years ago warned that children could be especially vulnerable to mobile phone emissions because of their thinner skulls and developing nervous system.
However, the Health Protection Agency, which is responsible for safety in this area, has stated that as far as adults are concerned, wi-fi, phones and radio masts all operate on a power level that is well within the accepted guidelines, and that there is no evidence that they pose a threat to people's health.
Speaking last September, the chairman of the MTHR programme, Professor Lawrie Challis, said: "There is no evidence for immediate or short-term health effects" — though he added there was a "slight hint" of increased risk of brain tumour among long term users.
There have not been any official studies on children, but because children have been shown to react differently to environmental stimuli, Professor Challis said it was "possible that they were at greater risk".
The advice to parents is to limit children's use of mobiles, and ensure that those under the age of eight do not use them at all.
For some experts, this warning does not go nearly far enough. Professor Denis Henshaw, head of the human radiation effects group at Bristol University, says: "We are steeped in denial over the safety of mobile phones and related technologies."
He points, as an example, to a recent Austrian study which found a raised risk of breast cancer near phone masts. "We have emission levels in the UK similar to those in Austria — and yet there is no warning to people of possible dangers."
Contrast the UK position with that in other countries, where at the very least they take the approach that when it comes to this new technology, better safe than sorry.
The German government has taken a more cautious line over wi-fi. Last September, the German environment ministry recommended that people should keep their exposure to radiation as low as possible by replacing wi-fi with a cabled connection.
In 2006, the city of Frankfurt decided not to install wireless systems in schools until there was more health research.
In Austria, there is a much greater level of professional concern about the possible dangers. Three years ago, the Vienna Chamber of Doctors put up more than 21,000 posters in surgeries and other places with very specific warnings about mobile phones, such as: "Use your phone as little as possible" and "Men - never keep a phone in your trouser pockets as it can reduce fertility."
A study reported last month found that out of 360 men attending an infertility clinic, those who used their mobile the most had the poorest sperm quality.
The Austrian Medical Association is currently lobbying against the installation of wi-fi in schools. "Children using a laptop that is broadcasting wi-fi are very close to the antennae," says Dr Gerd Oberfeld, the association's spokesperson 23 research projects.
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Yet there has been a considerable amount of other research suggesting the technology might not be so safe after all.
For instance, last October, two Swedish professors pulled together the results of 11 studies involving people who had used mobiles for more than a decade and found they were 20 per cent more likely to develop a benign tumour in the inner ear, and 30 per cent more likely to develop a type of brain tumour known as a malignant glioma.
Last summer, a group of 25 international scientists — known as the BioInitiative Working Group — carried out a major review of the evidence for the effect of microwaves on health.
They found evidence for a raised risk of brain tumour from mobile phones, and also expressed concern about a possible raised risk of breast cancer, changes to genes, and inflammation in the blood vessels associated with conditions such as heart disease.
And it's not just mobiles and phone masts that are being implicated. Some experts are concerned about wi-fi networks which allow you to connect your computer directly to the internet without the need for wires.
These wi-fi networks are found increasingly in homes, offices and schools, as well as in cafes, hotels and other public places.
Last month, this long-running issue was given a new twist with the publication of a survey which found that cordless phones - used in millions of homes and offices - give off more radiation than mobile phones. The reason is that the base acts like a mini mobile phone mast, constantly broadcasting a signal.
All of these - mobile phones and masts, cordless phones and wi-fi networks - use microwaves. The fear is that these might affect on environmental issues. "There is a huge amount of evidence that being that close to an aerial poses a danger to human health."
The local government authorities of the province of Salzburg have already advised schools not to install wi-fi. Oberfeld says: "There are some perfectly good, safe alternative ways of connecting to the internet, such as infra-red."
Infra-red uses light, which our bodies are used to, rather than microwaves. Eighteen months ago, nearly 50 scientists at a meeting of the International Commission for Electromagnetic Safety in Benevento, Italy, agreed on a statement warning about the dangers of microwave emissions.
The scientists came from a range of top academic institutions, including COlumbia University in the U.S., the Karolinska Institute in Sweden and the University of Washington in Seattle.
There was now evidence, the commission said, that long-term use of mobile phones could raise the risk of cancer in children and brain tumours.
These scientists called on governments to promote alternatives to wireless systems, tell people about the potential risks of mobile and cordless phones, and to limit their use by children and teenagers.
But while part of the debate is about which bits of research to take notice of and which shoudl be ignored, there is also a more fundamental difference over what are "safe" levels of intensity of microwave exposure.
The UK's levels are well within the recommended levels set by the International Commission on Non-Ionising Radiation Protection in 1998 - so how can there be any risk?
These levels were aimed at preventing any possibility of heating damage through microwaves.
But the big question now is whether microwaves can affect us not by heating, but by interfering with the activity of cells in our bodies at a power level way below the current safety levels.
The possibility of these "non-thermal" effects was raised eight years ago in a major report on mobile phone safety by Sir William Stewart, then chairman of Tayside University Hospitals NHS Trust and now head of the Health Protection Agency, the body responsible for monitoring microwave safety.
However, the report by the Mobile Telecommunications and Health Research programme last September concluded that there was no evidence for an effect other than heating and that there was "no need to support further work in this area".
It's not a view shared by the Benevento scientists in their statement in 2006: "Arguments that weak (low intensity) electromagnetic fields cannot affect biological systems do not represent the current spectrum of scientific opinion."
Indeed, the BioInitiative review last summer went further and called for safety levels to be lowered to reflect these non-thermal effects of microwaves on our bodies.
Last month, the Irish Doctors Environmental Association said that the current thermal-based guidelines were clearly no longer appropriate and called on the government to "immediately start research into the non-thermal effects of exposure to electromagnetic radiation".
"There is absolutely no doubt these effects exist," says Dr Andrew Goldsworthy, a biologist and expert in low frequency microwave radiation, and honorary lecturer at Imperial College in London.
"For instance, we've known for more than 30 years that electromagnetic fields affect the behaviour of calcium in living cells."
He claims that this could explain the symptoms reported by people who say they are affected by pulsed microwave radiation - the sort emitted by mobile phones.
"The textbook symptoms of too little calcium - such as fatigue, muscles cramps, irregular heart rhythm and gut problems - are very similar to those reported by people who say they are affected by microwave radiation," he says.
Professor Henshaw of Bristol University agrees. The idea that microwaves don't affect our health is "a total red herring", he says.
"The real question is: Why should anybody who understands physics and biology be surprised that low level radiation has an effect on health?
"We need to start thinking about microwave radiation the way we think about atmospheric pollution caused by cars," suggests Henshaw.
"We know that cars emit harmful chemicals: we can even calculate the number of premature deaths caused as a result (around 20,000). But we have rules and regulations on emissions - with the result that while car numbers continue to rise, pollution levels have fallen.
"Mobile phones and the rest aren't going to go away, but could we do more to acknowledge the possible problem so people can make an informed choice about using them and can learn to deal with the effects?"
The need for better warning is echoed by electromagnetic research group Powerwatch, which believes that mobiles should come with a health warning, like cigarettes.
"The evidence that passive smoking causes harm is actually much weaker than the evidence for damage by pulsed low frequency microwaves,' claims Graham Philips, Powerwatch's technical manager.
The media is sometimes accused of creating false debates over health and safety, setting the opinion of one or two renegade scientists against the evidence-based authoritative view of the majority.
The authority of the scientific sceptics suggests this isn't what is going on here. The one thing that both sides more or less agree on is the need for more research.
The last word, then, to the Health Protection Agency. "I've not seen any evidence that suggests I should be worried about my personal health as a result of using a mobile phone," says the agency's spokesman Dr Michael Clark.
"Street lamps emit radiation and I'm not worried about them. Radio waves are just next to microwaves on the electromagnetic spectrum and I'm not worried about listening to Radio 4 either. But I keep an open mind on the subject."
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