Long-term users of mobile phones are significantly more likely to develop a certain type of brain tumour on the side of the head where they hold their handsets, according to new research.
A large-scale study found that those who had regularly used mobiles for longer than 10 years were almost 40 per cent more likely to develop nervous system tumours called gliomas near to where they hold their phones.
The new research, to be published later this year in the International Journal of Cancer, is the second study to suggest increased risks of specific types of brain tumours in regions close to where mobile phone emissions enter the head.
However, a number of other studies have found no increased health risks associated with mobile phone use.
Prof Lawrie Challis, the chairman of the government-funded Mobile Telecommunications Health Research (MTHR) programme, said last week that most research had shown that mobiles were safe in the short term but that there was a "hint of something" for longer-term users.
Prof Challis, who is negotiating funding for a long-term international study, said last night: "I agree with the authors that this is a hint that needs further exploration. It's further reason why a long-term study is necessary."
Louis Slesin, the editor of Microwave News, a US newsletter on radiation and health that reported the new study, said: "We now have two tumour types found among people who use mobiles for more than 10 years shown by two different research groups. That is compelling evidence."
Researchers from the Radiation and Nuclear Safety Authority in Finland compared the mobile phone use of 1,521 people with gliomas with that of 3,301 people without the cancers.
Before separating out long-term users or looking at the different risks of developing tumours on the side where users held the phone, the scientists found no link between mobile use and gliomas.
However when they looked only at people who had used a mobile for 10 years or more, they found that they were 39 per cent more likely than average to get a glioma on the side of their head where they held their handset.
Prof Anssi Auvinen, an epidemiologist involved in the study, said: "It seems credible as it was after long-term exposure — which makes sense in terms of the length of time it takes for tumours to develop — and it is localised to the side of the head where the handset is held."
A spokesman for the Mobile Operators Association said: "The overall results of this study do not show increased brain tumour risk in relation to mobile phone use.
"The findings related to tumour location are difficult to interpret."
