> Ionizing radiation is the main cancer culprit and you can be sure the sun emits far more such radiation - mainly in the form of UV rays - than your cell phone. Which is at frequency levels below visible - mainly microwaves I think.

I thought you were mixing them up at first, but re-reading you did get it right. To clarify, in case anyone else got confused too:

UV is just above the visible spectrum in frequency.

Microwaves are below infrared, below visible.

(from Wikipedia) "Radiation on the short-wavelength [high frequency] end of the electromagnetic spectrum—high-frequency ultraviolet, X-rays, and gamma rays—is ionizing, due to its composition of high-energy photons. Lower-energy radiation, such as visible light, infrared, microwaves, and radio waves, are not ionizing. The latter types of low-energy non-ionizing radiation may damage molecules, but the effect is generally indistinguishable from the effects of simple heating."

See here the EM spectrum for reference:

http://en.wikipedia.org/wiki/File:EM_Spectrum_Properties_edi...