People who believe that mobile telephone masts are causing them to feel unwell are deluding themselves, according to a study at Essex University.

The three-year study, one of the largest of its kind, found that such people do experience symptoms when they know that they are exposed to radio waves, but they cannot detect when the waves are turned on and off, disproving their belief that they are “radiosensitive”.

In double-blind trials – in which neither participants nor experimenters knew whether the signals were on or off – no health effects were detected. The finding adds to earlier research suggesting that radiosensitivity is an illusion.

Professor Elaine Fox said that radiosensitivity complainants had genuine symptoms, but phone masts were not the cause. In the past, she said, similar symptoms were reported in relation to TV sets and microwave ovens.

It appears that about 4 per cent of the population claim to experience symptoms and tend to project them on to new technologies. The project was designed to investigate whether the effect was caused by phone masts.

Volunteers who claimed to be radiosensitive were matched against those who did not. Both groups were told when the signals were being switched on and off. The radiosensitive group reported headaches and malaise, but the team concluded that the symptoms were triggered by the knowledge of exposure.

The researchers then conducted the double-blind trials. If radiosensitivity were a real phenomenon, alleged sufferers should have been able to detect changes and report symptoms. They did not.

Two of the 44 sensitive individuals, and 5 of the 114 controls, judged correctly when the mast was on or off in all six 50-minute tests – exactly the proportion expected by chance. Professor Fox said: “Belief is very powerful. There are real, clinical effects.”

David Coggon, of the University of Southampton, said: “This is consistent with earlier research in suggesting that symptoms of electrosensitivity are psychological in origin.”

The study was funded by the Mobile Telecommunications and Health Research programme, with half of the money provided by Government and half by the mobile phone industry.

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