Around 25 per cent of mobile phone users are under 18, yet they are most vulnerable to damage caused by radiation because their brains are still developing.

According to a report in The Ecologist, absorption of micro-waves of the frequency used in mobile phones is greatest in an object about the size of a child"s head. And because children have thinner skulls, radiation penetrates more deeply into their brain.

As their nervous system is still developing and their immune system is less robust, they"re more vulnerable than adults to the health risks of radiation, such as memory impairment, DNA damage and immune system dysfunction.

Worryingly, such risks may include cancer - a study of around 1,600 Swedish cellphone users with brain tumours in June this year reported a near threefold increase in tumours on the same side of the head as the mobile phone was held.

How to defuse: Reduce mobile phone use to an absolute minimum at any age; ensure the antenna is as far as possible from the head - half an inch makes a huge difference; when indoors, use the phone near a window; use a hands-free kit but keep the phone away from the body.