In vitro skin model for characterization of sunscreen substantivity upon perspiration
Wash-off and redistribution reduce efficiency
The results indicated that perspiration reduced sunscreen efficiency through two mechanisms, namely sunscreen wash‐off (impairing the film thickness) and sunscreen redistribution (impairing the film uniformity). Further, the researchers investigated how the sweat rate affected these mechanisms and how sunscreen application dose influenced UV protection upon perspiration. As expected, higher sweat rates led to a large loss of UV‐protection, while a larger application dose led to larger amounts of sunscreen being washed‐off and redistributed but also provided higher UV protection before and after sweating.
The study was published in International Journal of Cosmetic Science