Using a mobile phone will not increase your chances of contracting cerebral cancer, a four-year study conducted in the UK has concluded.

The results of the study, published today in the British Medical Journal, indicate that no matter how long you have used a phone for, or how frequently you make and take calls, your risk of developing a brain tumour remains the same.

The survey, conducted by the Leeds, Nottingham and Manchester Universities in conjunction with London's Insititute of Cancer Research, focused on the incidence of glioma - the most common form of brain tumour - in phone users.

The researchers interviewed 966 people, aged 18 to 69 years, with glioma brain tumours and 1,716 randomly selected healthy individuals. They were all asked about their mobile phone usage, including how long they had used mobile phones, the number and duration of the calls they made, and what make and model of phone they had used. The interviews took place between 1 December 2000 and 29 February 2004, and included people in the Thames region, southern Scotland, Trent, the West Midlands and West Yorkshire.

The results contradict earlier studies exploring potential relationships between brain tumour risk and mobile phone usage. For example, a Swedish study suggested an increased risk of tumours among phone users in rural areas - where base-stations are typically further apart, requiring handsets to operate at higher power. The UK study found no evidence to indicate such a link.

However, past studies have pointed to an increased incidence of tumours on the side of the brain closest to where users hold their phones, and the UK study also observed a "significant excess risk" here. However, the results indicate a parallel "significant reduction in risk" of tumours on the other side of the head, from which the researchers concluded that there is currently insufficient evidence to indicate whether the phenomenon is a real effect or may simply be a case of tumour sufferers attributing their cancers to their mobile phone usage.

The researchers also cautioned that widespread mobile phone usage has not been going on sufficiently long to provide a risk assessment beyond the short and medium term. ®