The biggest study to date into the effects of mobile-phone usage on long-term health was launched on Thursday, aiming to track at least a quarter of a million of people in five European countries for up to 30 years.
The Cohort Study on Mobile Communications (COSMOS) differs from previous attempts to examine links between cellphone use and diseases such as cancer and neurological disorders in that it will follow users' behavior in real time.
Most other large-scale studies have centered around asking people already suffering from cancer or other diseases about their previous mobile-phone use. They have also been shorter, since cellphones have only been widely used for about a decade.
"One of the limitations of research to date is that when you ask people about their mobile phone use say five years ago there's a lot of error," said Jack Rowley, director of research and sustainability at industry body the GSM Association.
About 5 billion mobile phones are in use worldwide. To date, groups such as the World Health Organization, the American Cancer Society and the National Institutes of Health have found no evidence that cellphone use harms health.
"Research to date has necessarily mainly focused on use in the short term, less than 10 years," principal investigator Professor Paul Elliott of the School of Public Health at London's Imperial College told a news conference.
"The COSMOS study will be looking at long-term use, 10, 20 or 30 years. And with long-term monitoring there will be time for diseases to develop," he said.
The COSMOS study forms part of the Mobile Telecommunications and Health Research Program (MTHR), a UK body funded by a variety of government and industry sources and run by independent experts, mostly university academics.
Professor Lawrie Challis from MTHR said: "Many cancers take 10, 15 years for the symptoms to appear. So we've got to address the question: Could there be something out there that we need to look at?"