Using your mobile for more than 15 hours a month triples the risk of getting brain cancer, scientists have revealed.
Intensive users, especially workers in the sales industry, are most at risk of developing brain tumours compared to those who are hardly use their phones, according to French experts who based the findings on 450 cases.
The results were published in the journal Occupational and Environmental Medicine.
Past studies have linked mobiles to cancer but have failed to provide conclusive evidence when other factors such as smoking were highlighted.
Isabelle Baldi, one of the lead researchers, said: "Our study is part of that trend, but the results have to be confirmed."
Researchers examined 253 cases of glioma and 194 cases of meningioma – the main types of brain tumour - between 2004 and 2006. These patients were compared with 892 healthy individuals.
Roger Salamon, of the University of Bordeaux, insisted: "There is no reason to panic. This does not mean that everyone who makes a call with a mobile phone is going to get a brain tumour."
In contrast to previous research the study found that cancer occurred on the opposite side of the brain to where the phone was used.
Scientists also conceded that despite the rapid evolution of technology leading to an increase in the use of mobile phones handsets now give out lower intensity radio waves.