Mobile phones do not raise risk of brain tumours in adults, but harms among highest users need investigating

A 10 year study into the health effects of mobile phone use has found no increase in the risk of developing brain tumours, but it concludes that further investigations are needed, as the analysis hints at possible elevated risk among heavy users.

Christopher Wild, director of the World Health Organization’s International Agency for Research on Cancer, which coordinated the Interphone study, said that although the findings were negative, the agency did not “rule out a risk of brain cancer from mobile phone use.”

He added, “Observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied by Interphone, particularly by young people, mean that further investigation of mobile and brain cancer risk is merited.”

The interview based, case control study is the largest investigation of the effects on health of mobile phone use to date (International Journal of Epidemiology doi:10.1093/ije/dyq079). It included 2708 patients with glioma and 2409 patients with meningioma together with 7658 matched controls from 13 countries, including the United Kingdom, Australia, Japan, and Canada. It was partly funded by the mobile phone and mobile network industries.

Elizabeth Cardis, research professor in radiation epidemiology at the Centre for Research in Environmental Epidemiology, Barcelona, and principal investigator of the study, told reporters on 17 May that users in the Interphone study “were light users compared with today.”

The median lifetime cumulative call time among users in the study was around 100 hours, with a median of around 2 to 2.5 hours of reported use per month.

However, among the heaviest 10% of users (>1640 hours over 10 years), use corresponds to about 30 minutes a day, it says.

The study found “some evidence of an elevated risk of glioma in the highest decile of cumulative call time [odds ratio 1.4 (95% confidence interval 1.03 to 1.89)], with the highest estimates seen for tumours in the temporal lobe and for subjects who reported having used their mobile phone mainly on the same side as that on which the tumour occurred.”

But it also emphasised that biases and errors limit the strength of the conclusions.

Dr Wild said, “You cannot change current [health] advice based on the Interphone study.”

But he added that national studies are ongoing and that in May 2011 “we will integrate all information—experimental and epidemiological—to make a full evaluation.”

The Interphone group is also examining the relation between mobile phone use and tumours of the acoustic nerve and parotid gland, said Dr Cardis.

She said that given the concerns about the increasing use of mobile phones among people aged 10 to 20 years, who were not included in the Interphone study, her research agency is also 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.

WHO says that given that an estimated 4.6 billion people use a mobile phone, “it is important to investigate, understand, and monitor any potential public health impact.”