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 …