Despite numerous studies indicating that cell phones pose no health risk to their users, a few studies have been released that suggest prolonged use might contribute to brain cancer. For the World Health Organization, that was enough to declare the phones "possibly carcinogenic" and to call for further studies on the link.
At least one of these studies was already in the works. Some specific features of how Denmark tracks its citizens have made that nation a convenient laboratory for long-term population studies. Now, one study has looked at almost the entire Danish adult population and found that having a cell phone doesn't seem to be associated with any additional risk of brain cancers.