After months of anticipation and rumour, the Interphone Study Group has published its results into the risk of brain tumours (glioma and meningioma) in relation to mobile phone use. Those results, printed in the International Journal of Epidemiology, have the following conclusions:

Overall, no increase in risk of glioma or meningioma was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation.

The research also appeared to show that mobile phone use actually reduced the overall risk of developing a brain tumour… but we'll come back to that in a moment.

Interphone started in 2000, following a feasibility study by the International Agency for Research on Cancer (IARC). The objective was to determine whether mobile phone use increases the risk of tumours in tissues that most absorb RF energy emitted by mobile phones.

The Interphone Study Group concluded with the following message:

A reduced OR (odds ratio) for glioma and meningioma related to ever having been a regular mobile phone user possibly reflects participation bias or other methodological limitations. No elevated OR for glioma or meningioma was observed ≥10 years after first phone use. There were suggestions of an increased risk of glioma, and much less so meningioma, in the highest decile of cumulative call time, in subjects who reported usual phone use on the same side of the head as their tumour and, for glioma, for tumours in the temporal lobe. Biases and errors limit the strength of the conclusions that can be drawn from these analyses and prevent a causal interpretation.

Interphone notes that the majority of subjects were not heavy mobile phone users by today's standards. The median lifetime cumulative call time was around 100 hours, with a median of 2 to 2½ hours of reported use per month. The cut-point for the heaviest 10% of users (1640 hours lifetime), spread out over 10 years, corresponds to about a half-hour per day.

It also says average usage has increased since the survey began, although this increasing use is tempered by the lower emissions, on average, from newer technology phones and the increasing use of texting and hands-free operations that keep the phone away from the head.

Dr Christopher Wild, Director of IARC, said "An increased risk of brain cancer is not established from the data from Interphone. However, observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied by Interphone, particularly in young people, mean that further investigation of mobile phone use and brain cancer risk is merited."

Professor Elisabeth Cardis, the IARC Principal Investigator, said "the Interphone study will continue with additional analyses of mobile phone use and tumours of the acoustic nerve and parotid gland. Because of concerns about the rapid increase in mobile phone use in young people − who were not covered by Interphone −, CREAL is coordinating a new project, MobiKids, funded by the European Union, to investigate the risk of brain tumours from mobile phone use in childhood and adolescence."

[PDF document; International Journal of Epidemiology]