Sunscreen Metrics and Labelling Guidelines

Unlike most other personal care products, sunscreen performance and efficacy is dependent on application characteristics, notably quantity. The most widely known and the oldest metric of sunscreen testing, the SPF (sun protection factor) predominantly measures protection against UVB. UVA-PF as a measure of protection against UVB and critical wavelength as a measure of sunscreen protection well into the UVA-HEVL spectrum reflect the knowledge about the contribution of UVA to photocarcinogenesis and UVA and VL to pigmentation and photoageing. In skin of colour, the impact of VL and IR is a concern, and therefore, the development of measuring the protective ability of sunscreens in these domains is welcome. It is interesting to note that in vivo testing for sunscreens excludes higher skin types, which make up a large proportion of SOC. Therefore, recent advances in photoprotection science, techniques such as the hybrid diffuse reflectance spectroscopy (HDRS) which is not dependant on an erythema end point, and metrics based on biological effective protection factors (BEPF) are anticipated to provide comprehensive insights on sun protection even in SOC and beyond a visible response to ultraviolet rays alone.