High frequency, high dose, more time of exposure, all types of man made electromagnetic radiation ; are harmful. Only protection from this radiation is better.
This is an everlasting discusion since more than 50 years ago...biological effects sof low level electromagnetic fields..one can find these days about 40000 paper in that field where 15000 say that are significant bio effect and 25000 say there are thermal effects and nothing else..and nealy all the RF safety rules are based on thermal effect ( 6 minutes integration time) and some safety margin.Selecting the right references one can proof any desired point of view..A nice example of democratic science.