It's been a while since cell phones came into being, and the Nordic countries in Europe were at the forefront, with Nokia and all. That is why a 20-year cancer study for Finland, Sweden, Norway and Denmark published just recently in the Journal of Epidemiology, carries so much weight in determining whether prolonged cell phone exposure causes cancer once and for all.
The Scandinavian countries, with their stellar public health systems, also have one of the best track records for recording cancer occurrences, with full details by type and frequencies, so they were also a perfect match from a scientific research standpoint.
In the end, it turned out that glioma cases, the broad type of brain and spinal cord tumors that would supposedly form from cell phone radiation, have not become more often than 15 years ago, when smartphones entered the fray in those countries. There is a slight increase in women, and an actual decline in men, but on the whole there is no direct correlation between tumors and cell phones in countries like Finland, which had 40% cell phone penetration as far back as 1997.