These 'concerns' have been around as long as cell phone service has existed for every single frequency and power level. I remember my mom worrying about it back when stuff was at 1G & 2G levels.
You have to realize that "high" power radio & other artificial EM transmissions have been going on ever since you were born pretty much everywhere. AM Radio, FM Radio, "wireless" TV, and todays cellphones and wifi base stations. Not to mention all the other radio traffic that is more specialized, like airplanes, HAM radio, police & emergency services, the military, the light you see from your lightbulbs, the EM radiation that emits from your electric wires running through your house, street or nearby electric transformer stations on and on.
None of it has resulted in secret harm and 5G will be no different. The stuff that is harmful will have a lot of warnings around it and won't be secret. Such as UV exposure from the sun.