A groundbreaking, $30 million study into cell phones has found a link between long term use and brain tumors.

The World Health Organization is about to reveal that its decade-long investigation has found the devices can lead to cancer — and the internationally-respected body will soon issue a public health message with its findings, London’s Daily Telegraph reported today.

The conclusion goes against years of assurances by cell phone companies and scientists that cell phone use is safe.

But last month, Sen. Arlen Specter (D – Pa) organized Senate hearings to examine health implications of talking on-the-go.

The WHO’s Interphone investigation’s results showed, “a significantly increased risk” of some brain tumors “related to use of mobile phones for a period of ten years or more,” the Telegraph reported today.

The study’s head, Dr. Elisabeth Cardis, said, “In the absence of definitive results and in the light of a number of studies which, though limited, suggest a possible effect of radiofrequency radiation, precautions are important.”

The project carried out studies in 13 countries, talking to tumor sufferers as well as healthy cell phone users, It interviewed 12,800 people.

The results will be officially published before the end of the year, according to the Telegraph.