Mobile phones and cancer rates
The use of mobile phones has skyrocketed since the 1980s. If mobile phones increase the risk of brain tumours, more and more people should now be developing them.
But the numbers of new brain tumour cases have not changed very much. For example in the UK, the rate of brain tumours has changed very little in the past decades - and the very small increase we have seen is thought to be due to better data collection. However, brain tumours can take many years to develop, so it is possible that incidence rates would only start rising after more time.