A study into the long-term effects of mobile phones and cancer was launched last week.
If a link is discovered, more people could be needing cancer treatment in the future.
After public concern that the use of mobile phones could lead to cancers such as brain tumours, the government set up the Independent Expert Group on Mobile Phones in 1999.
Now, Imperial College London has launched a study to monitor 90-100,000 Britons over a 30-year period to see if there is a relation. It will also examine 250,000 people across Europe.
Commenting on the launch, Kat Arney, science information manager at Cancer Research UK, said: "At the moment, scientific evidence tells us that using mobile phones for less than ten years does not increase the risk of cancer.
"But brain tumours often take a very long time to develop, so we welcome this new study, which will tell us more about any potential long-term risks of phones and changing technology."
Independent advice on private healthcare