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15.05.2025 - Cosmetics

Alternatives to in vivo testing of the sun protection factor (SPF)

Ultraviolet sun rays are the main cause of human skin damage, therefore comprehensive skin protection with sunscreens with high sun protection factors is essential.

Previously, the determination of SPF was done through in vivo studies according to ISO 24444:2019. This test method relies on voluntary subjects who allow their skin to be irradiated with UV light, which raises ethical concerns.

Therefore, in a consortium of cosmetic manufacturers and laboratories, intensive work has been done in recent years on alternative SPF determination methods, which have now been published.

ISO 23675:2024

Double Plate Method (DPM):

Pure in vitro method, which does not require voluntary subjects
Suitable for emulsions and alcohol-based one-phase formulations for determining static SPF
Not suitable for powders or sticks or for determining the water resistance of a product

ISO 23698:2024

Hybrid Diffuse Reflectance Spectroscopy (HDRS):

Hybrid method that allows non-invasive optical assessment without needing a physiological skin reaction
Suitable for emulsions and one-phase formulations
Not suitable for powdery sunscreen products

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