|Betreff: A lesson from the study|
|Von: Iris Atzmon
|Datum: Fri, 27 Jul 2007 14:55:16 +0300|
"There have now been at least 31 blind and double-blind studies" [what?? where are they? I.A.] and the overall result is a clean bill of health, according to Dr James Rubin [[another pyschologist]] , of the Mobile Phones Research Unit at Kings College London: 'The Essex study is one of the largest and most detailed of these experiments and its findings, that mobile phone signals are not responsible for the symptoms that some people describe, are in line with those from most other previous experiments."
Mobile phone masts do not cause harmful short-term health effects, according to a study of people who say they experience symptoms when they are close to them. The study deals another blow to the notion that low-level electromagnetic fields from cellphones or base stations are dangerous.
The researchers looked at 2G and 3G phone masts in a lab setting where both the participants and researchers did not know whether the equipment was turned on. The set-up was designed to mimic the output from a phone mast at 20-30 metres from the subject. "It looks like there was pretty good evidence that people couldn't detect the signals," said Elaine Fox at Essex University, who led the study, published yesterday in the journal Environmental Health Perspectives.
Of the 159 people who took part in the experiment, 44 said they were sensitive to electronic equipment. At first the participants were told when the electric field was turned on while being tested. Under these conditions, the electrosensitive participants reported unpleasant symptoms such as headaches and nausea. In three further tests the researchers subjected them to 2G radiation, 3G radiation or no radiation under "double blind" conditions, meaning that no one involved knew whether the equipment was switched on. Under these conditions two of the electrosensitive group and five of the control group correctly identified whether the electricity was on every time - no better than you would expect by chance alone.
The team also measured heart rate, blood volume pulse (a measure of pressure) and the sweatiness of the subject's skin. All of these should go up when the participants are experiencing unpleasant symptoms or anxiety. The electrosensitive individuals had generally higher scores than the control group for all three, but they did not change when the 2G or 3G radiation was switched on.
Anti-phone mast campaigners said the results were skewed by the fact that 12 volunteers who claimed to be sensitive to electronic equipment dropped out. "Even a child can see that by eliminating 12 of the original 56 electrosensitive volunteers - over 20% of the group - the study integrity has been completely breached," the campaign group Mast Sanity said in a statement. It argues that these people were presumably the ones most sensitive to the radiation.
Professor Fox counters that her team was still able to test 44 people, and of the dropouts none was able to identify correctly when the radiation was on or off in the first double blind test. The reduced numbers do mean that the statistical power of the experiment was compromised, though. Prof Fox estimates that there is a 30% chance that the experiment missed a real effect because of the smaller numbers.
Some anti-mast campaigners have been impressed by the study. "The Essex team have carried out one of the best-designed and executed studies to date," the campaign group Powerwatch said.
Prof Fox said that scientists and sufferers should now concentrate on finding the real cause of the symptoms. "If people are convinced that they are suffering because of mobile phone masts they don't investigate other causes," she said.
One survey found that 4% of people in the UK claim to be sensitive to electronic equipment. Many experience flu-like symptoms such as headache, streaming eyes or a burning sensation and for some these are so bad they opt to shield their homes with foil-lined wallpaper or even move to the country.
Flu-like symptoms blamed on mobile phone masts may be all in the mind, say scientists.
Campaigners claim up to five per cent of the population suffer from extreme sensitivity to the electromagnetic fields emitted by masts, televisions, hairdryers and other everyday items.
The effects can include headaches, joint pain, depression and fatigue.
In severe cases, sufferers may change job or even move home to try to cut the amount of radiation to which they are exposed.
But research suggests the condition may be psychosomatic.
In one of the largest studies of its kind, scientists from the University of Essex looked at whether proximity to mobile phone masts triggered symptoms in a group of 44 electrosensitive volunteers.
They carried out the same tests on 114 healthy men and women. They found that those with electrosensitivity felt unwell and complained of anxiety, discomfort and fatigue when they were placed near a mast that was switched on.
However, their symptoms remained unchanged when the mast was switched off.
Crucially, physical symptoms such as heart rate and blood pressure did not change whether the mast was on or off.
Lead researcher Elaine Fox said that while there was no doubt the electrosensitive individuals felt unwell, phone mast radiation was not at the root of their problems.
Instead, it is possible they are thinking themselves ill.
Professor Fox, whose work was part-funded by the mobile phone industry, said: 'We do know there is a very large literature showing that the placebo effect, the power of belief, is very powerful.
'There's nothing magical about that. There are real clinical, biological effects.
'If you really believe something is going to do you harm, it will.
'I'm pretty confident that it's not the electromagnetic field causing these symptoms.'
The professor, who is a psychologist, said it was natural for people to try to explain away their ills. She said: 'They might have a headache, and they notice on the train that someone has a mobile phone, so they immediately make the attribution, that it must be the mobile phone causing the problem.
'It is very natural to try to support a hypothesis rather than find evidence against it.
'We all do this but it becomes quite dangerous when it's to do with health symptoms.'
The results are published in the journal Environmental Health Perspectives.
However, campaigners questioned the validity of the findings, pointing out the figures may have been skewed by electrosensitive volunteers dropping out when their health deteriorated part-way through the study.
Alasdair Philips of Powerwatch, which investigates the alleged health effects of electromagnetic radiation, added: 'Good science isn't necessarily looking at people in a lab somewhere for a short time.
'I think now we're going to have to look at longer term exposure, using information from GPs in the community.'