Answer by Steven Fowkes:
The idea that sunlight increases skin cancer is a modern invention of dermatologists. In actuality, it is only sun over-exposure (redness) and sunburn that is well connected to increased risks of skin cancer. Regular sun exposure actually lowers the majority of skin cancer risks, especially those of melanoma–and malignant melanoma. Weekend warriors often do not get regular sunlight and are more likely to burn (or singe). But our distant ancestors likely got regular skin exposure, which maximizes D and minimizes most cancer risks, and minimizes body cancers, too.The use of PABA derivatives and other "activated" polyphenolics and aromatics is that they often become mutagenic and carcinogenic when chemically transformed by UV radiation. These mutagens and carcinogens can then absorb into the skin and influence the proliferation of basal cells.Here are some links and people you can follow:– Carole Baggerly– Oliver Gillie– John J. Cannell, MD– Michael F. Holick, MD, PhD– Henry LehoreThere is also information that sunlight has health benefits that are not linked to UV-B frequencies or vitamin D production.Good luck on your inquiries.