Schuz's team studied data on 420,095 Danish cell phone users (357,553 men and 62,542 women) who first subscribed for mobile service between 1982 and 1995 and were followed through 2002 -- meaning some were tracked for two decades. The researchers then compared their cancer incidence to the rest of Denmark's population. A total of 14,249 cancer cases were seen among the cellular telephone users, a number that was lower than would be expected for that population.
The study seems conclusive, especially because it was conducted over such an extensive period of time and the sample is large enough. But is does have some weak points; researchers did not differentiate heavy users from average and occasional ones. If the same study would have kept track of heavy users and then compared their cancer incidence with that of the common population maybe the results would have been affected, though personally I still donít believe cell phones are a health risk.