Are the electromagnetic frequencies produced by our modern technology causing increased incidence of melanoma?

This indeed is the case. These energies are very damaging to living cells and they are designed to be so. They cause changes in the energetics of mitochondrial metabolism and cause oxidative damage to DNA as a consequence of free radical production. This is the classical means through which cancer arises and the fact that the lesions are occurring on the skin is a testament to the fact that the energies received by the body itself begin to work against the person, even from the first contact, which is the external surface of the body and the consequences then become evident with formation of skin lesions.