What’s New in the Estimation of SPF and UVA-PF?

Abstract

Up to very recently the assessment of SPF was performed “in vivo” by ISO 24444 standard, while for UVA-PF ISO 24443 “in vitro” standard was used, which still needed and empirical coefficient derived from the SPF “in vivo” to normalize the results. Since some years ago, ethical critics have been made to the fact that human beings were submitted to UVA radiation to evaluate the SPF. The European Community recommended replacing those standards with new ones that allow all determinations to be made in vitro.

But, as simple it may seem the purpose, it could not be achieved because there was no good correlation between the results obtained by spectrophotometry and those obtained from human panels. Since December 2024, after an extended circular test performed in Europe monitored by the ISO/TC 217, Cosmetics Committee validated the new standards ISO 23675 (In vitro determination of Sun Protection Factor (SPF)) and ISO 23698 (Measurement of sunscreen efficacy by diffuse reflectance spectroscopy). With horizon 2025, these new ISO standards will replace the actual ones into the European Community and later, most probably, within Mercosur and America in general.

Due to their complexity, to be implemented they need expensive equipment and thorough training of technical personnel. Prudence would indicate preparing in time for the changes. If not, our enterprises (specially the smaller and those who are not internationalized and producing sun care cosmetics) will be handicapped. In this paper we try to present the new techniques, emphasizing the equipment needed. We do also an explicit critic on the fact that they are based on an irradiation source (Xenon arc) designed only for the 40o latitude of the northern hemisphere, compatible with the mediterranean summer sun in Europe, but not representative at other latitudes.