Two possible concerns with "radiation": a) individual rays/particles have enough energy to knock electrons off ("ionizing radiation"). This is dependent on wav

Two possible concerns with "radiation": a) individual rays/particles have enough energy to knock electrons off ("ionizing radiation"). This is dependent on wavelength/frequency, not the amount of radiation, so even small amounts can be possibly problematic. b) quantity of radiation brings enough energy to heat things up, cause damage through heating. Cell phones have neither problem.