I am not aware of any evidence that supports the notion that electromagnetic radiation in the GHz range at levels below what would cause actual burns have any detectable health effects. My impression is that people who are concerned about this have a poor understanding of what electromagnetic radiation is, and under what circumstances it becomes dangerous. They would do better to worry about staying out of the sunlight and other sources of ultraviolet electromagnetic radiation, which certainly can be quite dangerous.
This is because the energy quanta of the photon rises with the frequency (cf. the Planck relation), and at GHz frequencies it simply does not have enough energy to damage tissue, other than through heating (this is why you feel warm in the sunshine). Of course, if you crank up the frequency into the ultraviolet there is enough energy to damage the DNA in your skin, which can lead to skin cancer and/or damage the retina in your eyes, especially at high flux. Increasing the frequency still further gives the photon enough energy to strip electrons from atoms, to “ionise” them, and allows it to break chemical bonds, which is really quite bad indeed - this is why the dentist will leave the room while you’re having an X-ray done.
But the frequencies involved in wireless communication are many, many, orders of magnitude below this, and pose no danger to living organisms unless you’re exposed to hundreds of watts at very close range - in which case you’ll begin to feel uncomfortable long before any damage is done. Otherwise, the sun would already have killed you long before you got your first mobile phone.
Didn’t we all learn this in school anyway?