I’m fuzzy on exactly what freqs are where on the spectrum, but I’d bet there are already things considerably worse than 5G baking our brains all the time already. Only case they can make is that the short range of 5G and the limited coverage will mean you’ll have 50 transmitting stations bombarding you at the same time, instead of 1 like you used to. 

But….that’s still a city folk problem. Or guys w/ poor em shielding in their home, supposedly the higher band 5G stuff can’t even pass through windows, right?