Image caption Are mobile phones safe?

Mounting evidence suggests there is no link between mobile phones and brain cancer, according to a review by the Institute of Cancer Research.

It stated that despite near universal mobile phone use, there had been no jump in the number of tumours.

Its report, in Environmental Health Perspectives, also identified flaws in many studies investigating a link.

A few weeks ago the World Health Organization said mobiles were "possibly carcinogenic".

The decision by the WHO's International Agency for Research on Cancer (IARC) put mobile phones in the same category as coffee, in which a link could not be ruled out, but it could not be proved either.

Heavy users

One of the biggest studies into a link was Interphone, a comparison of 2,708 patients with a brain tumour (glioma) with a similar number of people without.

The study concluded that mobile phone users were less likely to get brain tumours, but heavy users had an increased risk.

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Professor Anthony Swerdlow, from the Institute of Cancer Research, said there was a risk of bias when patients with brain tumours answered questionnaires about their phone use.

Ten patients in the study said they were on the phone for more than 12 hours per day.

He added that in the space of 20 years, mobile phone use had gone from being rare to 4.6 billion users worldwide.

Yet evidence from many Western countries showed "no indication of increases in brain tumour incidence".

Professor Swerdlow said: "The trend in the accumulating evidence is increasingly against the hypothesis that mobile phone use can cause brain tumours in adults."

Childhood exposure

The report admits that there is still some uncertainty.

Continued research is needed... but the news so far is good Professor David Coggon, University of Southampton

Studies have looked at a link associated with 10 to 15 years of mobile phone use and it remains a possibility that longer exposure could cause cancer.

However, Professor Swerdlow argues that if studies looking at longer exposure produce similar results, then a link will become "increasingly implausible".

He adds that "there is far less evidence of the effect of childhood exposure, but there is no reason to believe it causes tumours".

Cancer Research UK's Dr Joanna Owens said: "Although these researchers admit that we can't entirely rule out the idea of a link between mobile phones and brain cancer, they remind us that in most of the research, including their large international study, mobile phone users don't seem to be at increased risk.

"We don't yet have data on very long-term use of mobile phones, or for the effects on cancer risk in children, so it is probably wise to encourage children to limit their mobile phone call time."

Professor David Coggon, University of Southampton, said: "This is a carefully considered review, and the conclusions are justified.

"Mobile phones appear not to cause brain cancer in the first 10-15 years after people start using them.

"Continued research is needed in case there are harmful effects in the longer term, but the news so far is good."