A standardized scoring method for measuring white cast of mineral sunscreens across diverse skin tones

Summary: Abstract Body: Mineral sunscreens, using zinc oxide (ZnO) and titanium dioxide (TiO2) as physical UV filters, are a preferred choice for users with sensitive skin or allergies to chemical UV filters. However, the white cast they can leave on the skin is a significant cosmetic concern. This cosmetic elegance issue often discourages users from applying or using sunscreen correctly, leading to poor sunscreen compliance and a higher risk of developing skin cancer. Despite this, no official method exists to quantify white cast across diverse skin tones. To address the lack of a standardized method for measuring white cast in sunscreen formulations, we developed a validated protocol for measuring and scoring white cast. Our double-blind clinical study on a diverse Individual Typology Angle (ITA°) panel of volunteers combined objective L* measurements (whiteness) taken after sunscreen application with subjective user feedback on formulations containing ZnO concentrations ranging from 0 to 30%. The findings revealed a significantly strong correlation between increasing ZnO percentages and higher L* values (p < 0.001), corresponding to a more pronounced white cast. White cast scores for ZnO formulations were consistent across different skin tones, with higher ZnO concentrations leading to unacceptable levels of white cast. This study introduces a validated white cast score protocol as a quantitative tool for evaluating mineral sunscreen formulations in diverse skin tones, allowing the early selection of formulations with a reduced white cast and enhanced cosmetic elegance. These findings can lead to the production of mineral sunscreens that provide an improved user experience and encourage better sunscreen compliance. Alexandra M. Maldonado López¹, Emily Gallagher¹, Aiden Curry¹, Kylie Q. Sahloff¹, Ivan D. da Silva Souza¹ 1. R&D, Good Molecules, Philadelphia, PA, United States. Clinical Research: Epidemiology and Observational Research