> But for radio waves? There's nothing, no hint of how any harm might occur, short of being put in a microwave oven and receiving thermal burns.

To preface: I don't think there's any evidence at this time that standard levels of non-ionizing electromagnetic radiation are harmful to humans.

But it's not inconceivable that there could be some harm caused which we're not aware of yet and which is eventually discovered in the future. The body and brain are extremely complex and not fully understood, etc. Molecular biology is sensitive. It's not implausible that there could hypothetically be certain chemical reactions or cell processes which are subtly disrupted by certain frequency bands at certain amplitudes.

I personally don't think there will be such a finding, but people still need to keep an open mind, I think.