SPF Assessment Revisited – Status and Outlook

We present the latest alternatives to the in vivo SPF gold standard and discuss their potential and procedures for their validation. The relevance of erythema as SPF endpoint is undisputed, especially as erythema and at least non-melanoma-skin-cancer share a similar action spectrum. Skin and sunscreens interact in a complex fashion, producing an absorption phenomenon far removed from the laboratory cuvette. This continues to represent a significant trueness challenge for any replacement method. We have choices for an alternative method, from in silico and in vitro which require no human testing to a hybrid that involves humans but with negligible irradiation burden. Performing method validation is a key step in the process and requires a solid data foundation to select a suitable method that assures future success.