Title : What´s new in the estimation of SPF and UVA-PF?
Abstract:
For the last 20-30 years there has been no real change in the way in which sunscreens were tested regarding the protection given while applied in cosmetic formulations to human skin.
The “Gold Standards” in Europe and other countries, including Mercosur, where ISO 24444 for the SPF and ISO 24442 for the UVA-PF. Both are “in vivo” methods, performed on human volunteers. Later, for the UVA-PF the ISO 24443 “in vitro” standard method was developed, which still needed the value obtained for the SPF “in vivo” to normalize both to a common scale.
In the USA, the FDA maintained their own methodologies, which differ from those cited previously by the way to estimate the UVA protection (critical wavelength).
All these approaches had serious drawbacks and ethical concerns. To begin with, the need to “burn” the back of human beings to calculate the experimental SPF via the erythema produced. Then, low reproducibility, high inter lab variability, inclusion-exclusion problems, and low correlation between the “in vivo” and “in vitro” experiments.
For these reasons the international experts have been looking for alternatives “in vitro” that would be reliable and reproducible. Last year (2024), after extensive inter lab experiences, they validated two alternatives that would fulfill the requisites: ISO standard 23675 (SPF “in vitro”) and ISO standard 23698 (HDRS, Diffuse Reflectance Spectroscopy).
In this conference, the principles and advantages of both methods will be explained, analysing the differences with the former ones.
Audience Takeaway:
- The audience will be able to understand the new methods and compare with the former.
- In their daily practice the dermatologists will be more comfortable from the ethical point of view.
- The results obtained will be more reliable and comparable.
- When universally adopted, the labeled values of SPF and UVA-PF would be comparable in every geographical region.
The equipment for HDRS technique can also be used to study skin pathologies, and eventually to extend studies to the blue light and IR regions.
