In vitro skin model for characterization of sunscreen substantivity upon perspiration

Fatemeh Keshavarzi, Nina Østergaard Knudsen, Jonathan R Brewer, Morten F Ebbesen, Niloufarsadat Mirmahdi Komjani, Saeed Zajforoushan Moghaddam, Shadi Jafarzadeh, Esben Thormann*

*Kontaktforfatter for dette arbejde

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review


Objective: The resistance of sunscreens to the loss of ultraviolet (UV) protection upon perspiration is important for their practical efficacy. However, this topic is largely overlooked in evaluations of sunscreen substantivity due to the relatively few well-established protocols compared to those for water resistance and mechanical wear. Methods: In an attempt to achieve a better fundamental understanding of sunscreen behaviour in response to sweat exposure, we have developed a perspiring skin simulator, containing a substrate surface that mimics sweating human skin. Using this perspiring skin simulator, we evaluated sunscreen performance upon perspiration by in vitro sun protection factor (SPF) measurements, optical microscopy, ultraviolet (UV) reflectance imaging and coherent anti-Stokes Raman scattering (CARS) microscopy. Results and conclusion: 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, we 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.

TidsskriftInternational Journal of Cosmetic Science
Udgave nummer3
Sider (fra-til)359-371
StatusUdgivet - jun. 2021

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