Ultraviolet Radiation and the Skin: Photobiology and Sunscreen Photoprotection
There is ample evidence to demonstrate the acute and chronic skin alterations caused by solar range UVR, and the benefits that sunscreens afford in the reduction and even prevention of such changes.
Regulatory standards for sunscreens differ around the world. In the United States sunscreens are regarded as over-the-counter drugs, and in Canada they are considered drugs unless they contain only titanium dioxide, zinc oxide, or para-aminobenzoic acid, where they are defined as ‘‘natural health products.’’
Despite the development of new filters systems and broad-spectrum products, education of consumers and patients regarding the application of sunscreens, both in terms of quantity and quality, should be a priority for dermatologists and public health organizations. Many questions remain regarding the exact level of protection for each hazardous sun effect on our skin. New robust methods for evaluation of sunscreens efficacy have been developed in recent years, including quantitative analysis of UVR damage (transcriptomic and proteomic analyses, 2-photon fluorescence microscopy, immunohistochemistry) and may help to differentiate the efficacies of different sunscreens formulations in the future.