Phone and cancer link elusive

One of the most comprehensive studies into the dangers of mobile phones has found no link between how often they are used and the risk of developing brain tumours.

But scientists said although they could not establish a link between the two, they could not rule out the possibility that mobile handsets may cause long-term health problems, and even head cancers.

Researchers questioned more than 1200 people, of whom 822 were healthy and 427 had brain tumours.

When they compared the two groups they found the risk of developing a brain tumour was not related to the frequency of mobile phone calls or the number of years the phones had been used.

Christoffer Johansen of the Danish Cancer Society in Copenhagen said the findings supported earlier studies that found no links between brain tumours and mobile phones.

"I think we're becoming more convinced that the use of mobile phones does not pose a risk in terms of brain cancer," Professor Johansen said.

"In terms of brain tumours the door is now more closed than it was on the question, but before we can turn the key in the lock we would need to study a high number of long-term, heavy users of mobile phones."

The Danish study looked at the two main types of brain tumour - glioma and meningioma - and found neither was related to mobile phone use.

They also found no association between the side of the head habitually used by a mobile phone user and on which side of the brain a tumour developed.

By checking the mobile phone bills of 27 people with brain tumours and 47 people without tumours, the researchers were also able to assess how good their memory was in terms of how they recalled using their phones.

They found that people accurately remembered the number of calls they made but did not accurately remember the length of those calls.

The scientists also checked to see whether patients with tumours were more likely to exaggerate their mobile phone habits than healthy patients - they were not.

"We've no reason to believe that the people who took part in the study were not reporting their phone use faithfully," Professor Johansen said.

Several laboratory studies have suggested that the radiation from mobile phones could damage living tissues.

One in particular demonstrated that a long conversation on a mobile phone can cause small temperature rises in the brain.

But most large-scale epidemiological studies have failed to find a link between ill health and mobile phone use.

Nevertheless, some have found a statistically significant association, Professor Johansen said.

"There have been a few studies that found an increased risk of brain tumours with cellphone use, but those studies have been criticised for problems with the study design.

"Taken together, the weight of evidence does not indicate that cellular telephones are a risk factor of glioma or meningioma of the brain.

"Nevertheless, in all the studies the numbers of long-term users and heavy users are limited, obviating any firm conclusion.

"In our study, few people reported regular cellular telephone use for 10 years or more.

"We won't be able to make any firm conclusions until we can confirm these results with studies with more long-term and heavy cellphone users," he said.

An official inquiry into the health risks of mobile phones in Britain has recommended that children under 8 should not be allowed to use phones and older children between eight and 14 should use them only when absolutely necessary.

Professor Johansen said the latest study published in the journal Neurology was the most comprehensive and detailed so far but it did not include children.

As well as studying long-term adult users, Professor Johansen said the next phase of the research was to investigate the small number of children with brain tumours to see if they could be linked with mobile phone use.

Cellphones and tumours

* The study found no link between mobile phone use and the two main types of brain tumours in adults.

* The authors say a link cannot be ruled out until a study is made of heavy, long-term users of mobile phones.

- INDEPENDENT