Time spent in front of PCs at work could result in runny noses, itchy eyes and short-term memory loss, users were warned last week.
But the research that prompted the warning was dismissed by a prominent academic as rubbish.
Professor Derek Clements-Croome of Reading University and ergonomic consultant John Jukes carried out a study at the Southampton Health Authority, in which 100 workers were divided into two groups.
One group used PCs fitted with a device said to reduce the effect of radiation and the other with machines using dummy devices.
After four weeks, participants were asked whether they had suffered from any of a range of 19 symptoms, including backache, runny nose and short-term memory loss.
The real devices and dummies were then swapped for a further four weeks, and everyone was again quizzed.
Researchers did not release to PC Week full figures from the survey, detailing exactly what symptoms were reported by whom. They said only that the number of symptoms experienced by those with the real screening devices dropped by an average of 36%.
The device said to reduce monitor radiation is the Tecno AO, which can be bought for £67. It reportedly contains crystals that vibrate at the same frequency as the human body, countering radiation.
Jukes told PC Week: "The low-frequency magnetic field emitted from VDUs causes circulating currents in the body, which mimic and confuse the body's own bio-electricity and shift brain pattern into a higher level, simulating stress." This stress then causes the symptoms that the survey reported.
But Dr Derek Roger, a York University stress specialist, labelled this theory "crap".
"There is no real evidence that electromagnetic fields cause changes in the body," he said, "and even if they did, it would not cause stress. Stress stems from emotional upset."
See leader comment, p20.
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