EDIT: I didn't consider dielectric heating (https://en.wikipedia.org/wiki/Dielectric_heating). Seeing as how microwave ovens have 500W rating on the low end, I assume heat generated by 10W source can be dissipated fast enough that proteins don't get denatured even if it's directed at a small area of the body.
Most energetic photon in radio frequencies has wavelength of 1mm and energy of 0.00124eV (http://www.photonics.byu.edu/fwnomograph.phtml) I think. Would just pass through a single cell as cell is much smaller than the wavelength. And 0.0012eV is really small amount of energy. "Van der Waals bonds are weak bonds with a dissociation energy of about 0.01 eV" (http://lamp.tu-graz.ac.at/~hadley/ss1/crystalbinding/bonds/b...) I wouldn't expect it to do anything cellular/molecular level.
Not really a biology person so don't know if there's some effect on aggregate of cells on the millimeter level that could be harmful. Human body's electrical resistance inside is high and through skin is higher so I don't expect much effect on that scale either?
I'm no biology person either, but in terms of photons, I do find these interesting;
'Biological tissues typically produce an observed radiant emittance in the visible and ultraviolet frequencies ranging from 10−17 to 10−23 W/cm2 (approx 1-1000 photons/cm2/second).[1] This low level of light has a much weaker intensity than the visible light produced by bioluminescence, but biophotons are detectable above the background of thermal radiation that is emitted by tissues at their normal temperature.
While detection of biophotons has been reported by several groups,[2][3][4] hypotheses that such biophotons indicate the state of biological tissues and facilitate a form of cellular communication are still under investigation,[5][6] and claims that biophotons are responsible for physical healing are unsupported. Alexander Gurwitsch, who discovered the existence of biophotons, was awarded the Stalin Prize in 1941 for his mitogenic radiation work.[7]'
Most energetic photon in radio frequencies has wavelength of 1mm and energy of 0.00124eV (http://www.photonics.byu.edu/fwnomograph.phtml) I think. Would just pass through a single cell as cell is much smaller than the wavelength. And 0.0012eV is really small amount of energy. "Van der Waals bonds are weak bonds with a dissociation energy of about 0.01 eV" (http://lamp.tu-graz.ac.at/~hadley/ss1/crystalbinding/bonds/b...) I wouldn't expect it to do anything cellular/molecular level.
Not really a biology person so don't know if there's some effect on aggregate of cells on the millimeter level that could be harmful. Human body's electrical resistance inside is high and through skin is higher so I don't expect much effect on that scale either?