A woman wearing protective mask talks on the phone in Lviv, October 31, 2009. Credit: Reuters/Vasily Fedosenko

Organizers said the Cohort Study on Mobile Communications (COSMOS) would be the largest of its kind, examining more than 250,000 people aged 18 to 69 in Britain, Finland, the Netherlands, Sweden and Denmark.

Professor Paul Elliott, the Principal Investigator at the Imperial College London on the British study, said previous research examining the health link had so far been reassuring but pointed out these had often only lasted around 10 years.

With many cancers taking longer to develop and mobile phones still being relatively new, Elliott said there was a need for a longer-term study.

For the sake of current users and future generations this is the sensible thing to do, he told a press conference in London. Research to date has necessarily mainly focused on (mobile phone) use on the short term, less than 10 years.

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.

Groups such as the World Health Organization, the American Cancer Society and the National Institutes of Health, have all concluded that scientific evidence to date does not support any adverse health effects associated with the use of cell phones.

Professor Lawrie Challis from the independent MTHR group which will fund the British part of the study said the balance of scientific evidence did not suggest that mobile phones caused cancer.

But we cannot rule out the possibility that it might, he said. There just hasn't been enough time. Most of us have not had mobile phones for more than 10 years.

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.

The study will work with mobile operators to examine a participant's mobile phone use whether making calls, sending texts and downloading data.

It will also look at how users carry their phone, such as in a trouser or chest pocket and whether they use hand-free kits.

Participants who agree to take part in the study will fill in an ongoing online questionnaire about their mobile phone use, health and lifestyle.

The professors said many of the studies into mobile phone use had only looked for a link to cancer, whereas the COSMOS study will examine all health developments and look for links to neurological diseases such as Alzheimer's and Parkinson's.

The large selection of participants will also include those who use mobile phones more than others, allowing the scientists to examine what impact increased use has.

The study will announce its findings as it progresses.