A new study has found no increase in the incidence of brain tumours during the years immediately following the introduction of mobile phones in Nordic countries.
Scientists at the Institute of Cancer Epidemiology in Copenhagen analysed the annual incidence rates of two of the most common types of brain cancer - glioma and meningioma - among over-20s in Denmark, Finland, Norway and Sweden.
They found that 59,984 men and women out of a population of 16 million adults were diagnosed with one of these types of cancer between 1974 and 2003.
The use of mobile phones increased sharply in the mid-1990s in these countries, yet the incidence of brain cancer did not rise between 1998 and 2003, as would have been expected if the devices increased the risk of the disease within five to ten years of use.
The findings, which are published in the Journal of the National Cancer Institute, support other studies, which indicate that mobile phone use does not increase the risk of brain tumours in the short or medium term.
But the authors cautioned that conclusions cannot be drawn from their study about the long-term effects of regular mobile phone use. And their analysis did not take into account the levels of individual people's mobile phone use.
"Because of the high prevalence of mobile phone exposure in this population and worldwide, longer follow-up of time trends in brain tumour incidence rates are warranted," the study authors wrote.
Dr Alison Ross, Cancer Research UK's senior science information officer, commented: "Overall, the scientific evidence tells us that using mobile phones for less than ten years does not increase the risk of cancer and this large study supports that conclusion.
"However, brain tumours often take a very long time to develop so we will need to look for any future changes in incidence rates to see if mobile phones could pose any longer-term risks."