Results from the largest study of its kind show that the risk of developing certain types of brain tumour are increased with the use of mobile/cell phones.
The worrying news has come out of research conducted by the International Agency for Research on Cancer which is part of the World Health Organisation (WHO).
Researchers report that the chances of developing a malignant tumour are "significantly increased" for people who have used a mobile phone for ten years or more.
They found that long term use of the phones was associated with an increased likelihood of developing a specific type of brain tumour known as a glioma.
This is a tumour affecting the glial cells of the central nervous system (CNS). These cells typically referred to simply as 'glia' act as a support network for neurones, the other major cell of the CNS which are responsible for carrying messages in the form of electrical signals. The glia serve to anchor neurones in place, supply them with nutrients and oxygen, insulate one neuron from another, and to destroy pathogens and remove dead neurons.
French scientists came to the conclusion after looking at data from 13 different countries and comparing the incidence of various types of cancerous tumours with mobile phone use.
Researchers admit the exact cause is currently unknown, but it is thought that biological changes that ultimately lead to the development of cancer could result from radiation given off by handsets. Mobile phones emit ultra high frequency (UHF) radio signals in the microwave range.
Professor Elisabeth Cardis, who led the study, said: "To underestimate the risk would be a complete disaster."
Last month a study in Sweden concluded that children and teenagers are five times more likely to get brain cancer if they use mobile phones. Scientists involved warned that young people may suffer an "epidemic" of the disease in later life.
Other experts have been cautious in jumping to conclusions however.
Commenting on the latest research, Professor Patricia McKinney of the University of Leeds told the British media that: "Reasonable use is unlikely to increase the risk of tumours."
Nevertheless, these studies are certainly worrying as mobile phones and other wireless devices such as those using Wi-Fi networks become a more and more integral part of everyday life.
Along with the potential risk for cancer development the wireless radiation on which these deveices rely may be causing other health problems. Indeed some people may be made chronically ill by exposure to such radiation. These individuals are said to suffer from electrical hypersensitivity.