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Cancer from Cellphones?
GET YOUR HEAD ROUND THIS...
By David Concar
Forget the hype--there's still no evidence that mobile phones will mangle your memories or give you cancer. But the microwaves they emit may be up to something. Meet the fast-growing worms and boozing rats that have the experts baffled...and discover why a phone call might make you quick on the draw
FOR ANYONE WHO USES a mobile, these are worrying times. "Mobile phone killed my man," screamed one headline last year. In February came claims that an unpublished study had found that cellphones cause memory loss. And last month, a British tabloid devoted its front page to a picture supposedly showing how mobiles heat the brain.
But speak to the scientists whose work is the focus of these scares and you hear a different story. First, there is no evidence that mobiles cause cancer or any other illness in people. You can also forget about mobiles "cooking" your brain--a mild bout of exercise will heat your head more than the puny microwaves that the devices emit. And finally, the study fuelling the latest claims about mobile phones scrambling the mind in fact shows nothing of the kind.
What we do have, however, are some tantalising results suggesting that cellphones' emissions have a variety of strange effects on living tissue that can't be reconciled with conventional radiation biology. And it's only when the questions raised by these experiments are answered that we'll be able to say for sure what mobiles might be doing to your head.
One of the weirdest effects comes from the now famous "memory loss" study, published this week in the International Journal of Radiation Biology (vol 75, p 447). Alan Preece and his colleagues at the University of Bristol clamped a device that mimicked the microwave emissions of analogue or digital mobile phones to the left ear of volunteers. Contrary to the press reports that appeared in February, the volunteers were as good at recalling words and pictures they had been shown on a computer screen whether or not the device was switched on. Preece says he still can't comment on the effects of using a cellphone for years on end. But he rules out the suggestion that mobiles have an immediate effect on our cognitive abilities. "I'm pretty sure there is no effect on short-term memory," he says.
But the microwaves did have one completely unexpected effect: they decreased the time subjects took to react to words flashed onto the screen. When "yes" or "no" was displayed, the volunteers were quicker at pressing a matching button if the headset was switched on. The improvement was small--about 4 per cent when the device was set to mimic an analogue phone--but unlikely to be a freak finding, because it was seen in two groups of volunteers.
This seems like good news. But if microwave emissions can influence reaction times as they pass through the skull, what else might they be doing?
It's a good question, because in theory mobile phone emissions shouldn't do anything to living tissues (see "Explaining the inexplicable", p 23).
Preece speculates that the improvement in reaction times is caused by microwaves somehow speeding the flow of electrical signals through an area of the cerebral cortex known as the angular gyrus, which connects brain areas involved in vision and language. But he has no idea why this should happen.
This finding joins a growing list of unexpected effects ascribed to mobile phone emissions. Some of the most intriguing results come from David de Pomerai and his team at the University of Nottingham. They have been beaming microwaves at tiny nematode worms, chosen because their developmental and cell biology are well understood.
In one series of experiments, the team found that larvae exposed to an overnight dose of microwaves wriggled less and grew 5 per cent faster than larvae that were not exposed, suggesting that the microwaves were speeding up cell division.
The researchers now intend to examine mammalian cells to see if they divide more rapidly when exposed to microwaves--a finding that would raise fears about cancer. But de Pomerai insists that there is no reason to panic about the nematode data. "As a proportion of life span, exposing a nematode worm to microwaves overnight is like exposing a human continuously for an entire decade," he says.
De Pomerai is also trying to work out how microwaves could affect nematode biology. He already has evidence that "heat shock" proteins are produced in the exposed worms' cells. Despite their name, heat shock proteins are produced by cells in response to many kinds of stress that damage proteins, not just excessive heat. The heat generated by the microwaves in de Pomerai's experiments was too low to stimulate their production, so he believes microwaves do something else that induces stress.
Support for the idea that microwaves can trigger biochemical stress at low energies comes from a team led by Henry Lai at the University of Washington in Seattle. He claims that rats exposed to microwaves produce natural painkillers called endorphins and are more likely to binge on alcohol or react strongly to morphine and barbiturates. His team also has evidence from rats that exposure to microwaves unleashes corticotropin releasing factor, a stress hormone, and disrupts the ebb and flow in the brain of acetylcholine, a neurotransmitter involved in memory and alertness, among other things.
According to Lai, the changes are similar to those in rats exposed to stressful blasts of white noise and help to explain why rats exposed to microwaves take longer to learn the position of a submerged platform in cloudy water--another of his findings.
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