Wavelength not so much. From 700MHz to 5 GHz everything is in use. Now 3.4GHz (main 5G frequency) is right inbetween. Nearly noone is trying to build 5G networks with the high frequencies starting from 24GHz because you have a) no range and b) line of sight is preferred.
I think the main concern comes from the mM-wave frequencies from what I've read. The others are more of the same, but a lot of what I've seen--and I can't remember where at the moment--focused exclusively on the high frequency nodes that would (theoretically) be deployed in urban areas.
People don't realize they're exposed to mmwave already. If you're on a jet or ship, in sight of a jet or ship, near an airport (not just going through a body scanner), near a weather radar station, within line of sight of a microwave relay tower, walking through automatic doors, or driving, your body is absorbing mmwave RF from something. All of those sources are from radar, which is a lot more common than one might think.
