Sunscreens--what is the ideal testing model?

Sunscreen protection assessment methodologies have been evolving in tandem with the innovation and evolution of sunscreen products themselves; from initial human testing in the Swiss Alps, to laboratory testing with high intensity solar simulators, to spectrophotometers with modern CCD array photocells and diffuse reflectance spectroscopy techniques. The progress in the science leads regulatory development of standard methods, and provides new and improved ways to assess sunscreen protection properties. This review scans much of the history of the development of these methods and highlights the latest development in non-invasive sunscreen testing as an opportunity to improve accuracy while eliminating human UV exposures.