280w ago - Mobile phone use does not raise the risk of brain tumours, a Japanese study suggests.
The research is the first to look at the effects of hand set radiation levels on different parts of the brain.
Tokyo Women's Medical University found no increased risk of the three main types of brain cancer among regular mobile phone users.
The study, comparing 322 brain cancer patients and 683 healthy people, appears in British Journal of Cancer.
The cancer patients had one of the three most common types of brain tumour - glioma, meningioma or pituitary adenoma.
The researchers rated each subject according to how many years they had been using a mobile phone, and how long they spent talking on it each day.
They studied the radiation emitted from various types of mobile phone, and placed them into one of four categories relating to radiation strength.
And they also analysed how each phone was likely to affect different areas of the brain.
Lead researcher Professor Naohito Yamaguchi said: "Using our newly developed and more accurate techniques, we found no association between mobile phone use and cancer, providing more evidence to suggest they don't cause brain cancer."