The ALT-SPF ring study – in vitro determination of the SPF & UVA-PF by the fused method

IF 2.5 4区医学 Q2 DERMATOLOGY

International Journal of Cosmetic Science Pub Date : 2025-09-01 DOI:10.1111/ics.70015

S. Acker, A. Büchse, L. Nogueira, J. Zur Lage, E. Perroux-David, F. Drulhon, J. Moraes, S. Peters, A. Janssen, N. M. Komjani, B. Colson, B. Herzog

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Abstract

Objective

In the framework of the Alt-SPF consortium, a large ring study was conducted to evaluate different alternative methods for SPF determination. This paper reports and discusses the results of a new in vitro approach, the Fused Method. The study aimed to determine whether the Fused Method would provide similar SPF results to those obtained using ISO 24444 and whether UVA-PF would be comparable to ISO 24443.

Methods

The Fused Method is based on assessing UV transmittance through a film of sunscreen applied to PMMA plates, before and after 1MED irradiation through the film. An individual calibration curve is measured by each operator using standard sunscreens to correct for individual/equipment error throughout the process. This calibration is formulation-dependent: there is one calibration for emulsion, one for single-phase formulations, and one for mineral UV filters.

Results

Optimization of the calibration step to an asymptotic regression model improved inter-laboratory reproducibility and showed lower method bias compared to ISO 24444. Most PGs met the full statistical validation criterion for SPF results. The results of PG1 (low viscosity emulsion SPF30), PG2 (medium viscosity emulsion SPF6) and PG4 (medium viscosity emulsion SPF30) indicate a product and product group-specific method bias. This observation was confirmed for PG1 in the follow-up study. The same conclusion could be drawn for the evaluation of UVA-PF versus ISO 24443, as this parameter is directly linked to the SPF results.

Conclusion

The use of the Fused Method to determine the SPF of sunscreen formulations meets the statistical criteria for most PGs. However, intra-laboratory reproducibility needs to be improved for low SPF values and low viscosity emulsions. Nevertheless, this fast, simple, and cost-effective method remains a good alternative for SPF & UVA-PF screening in the development of sunscreen formulations. It is a pragmatic approach to manage the various known biases (applicator/device) of in vitro transmittance SPF measurement. No significant change to ISO 24443 is required, and the method allows in vitro SPF & UVA-PF to be determined in the same setup.

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ALT-SPF环的研究——用融合法体外测定SPF和UVA-PF

目的在Alt-SPF联盟的框架下，进行了一项大型环研究，以评估SPF测定的不同替代方法。本文报道并讨论了一种新的体外方法——融合法的结果。该研究旨在确定融合方法是否能提供与ISO 24444相似的SPF结果，以及UVA-PF是否能与ISO 24443相媲美。方法熔融法是基于在PMMA板上涂上一层防晒膜，在通过薄膜进行1MED照射之前和之后，评估紫外线透过薄膜的透射率。每个操作人员使用标准防晒霜测量单独的校准曲线，以纠正整个过程中的个人/设备误差。此校准与配方相关：乳液有一个校准，单相配方有一个校准，矿物紫外线过滤器有一个校准。结果与ISO 24444相比，将校准步骤优化为渐近回归模型，提高了实验室间的可重复性，降低了方法偏差。大多数pg符合SPF结果的完全统计验证标准。PG1（低黏度乳液SPF30）、PG2（中黏度乳液SPF6）和PG4（中黏度乳液SPF30）的结果显示了产品和产品组特定的方法偏差。这一观察结果在PG1的后续研究中得到了证实。对于UVA-PF与ISO 24443的比较，也可以得出同样的结论，因为该参数与SPF结果直接相关。结论采用融合法测定防晒霜配方的SPF值符合大多数产品的统计标准。然而，对于低SPF值和低粘度乳剂，实验室内的再现性需要改进。尽管如此，这种快速、简单、经济的方法仍然是在开发防晒霜配方时筛选SPF和UVA-PF的一个很好的选择。这是一种实用的方法来管理各种已知的偏差（涂抹器/设备）的体外透射率SPF测量。不需要对ISO 24443进行重大更改，并且该方法允许在相同的设置中确定体外SPF和UVA-PF。

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来源期刊

International Journal of Cosmetic Science DERMATOLOGY-

CiteScore

4.60

自引率

4.30%

发文量

期刊介绍： The Journal publishes original refereed papers, review papers and correspondence in the fields of cosmetic research. It is read by practising cosmetic scientists and dermatologists, as well as specialists in more diverse disciplines that are developing new products which contact the skin, hair, nails or mucous membranes. The aim of the Journal is to present current scientific research, both pure and applied, in: cosmetics, toiletries, perfumery and allied fields. Areas that are of particular interest include: studies in skin physiology and interactions with cosmetic ingredients, innovation in claim substantiation methods (in silico, in vitro, ex vivo, in vivo), human and in vitro safety testing of cosmetic ingredients and products, physical chemistry and technology of emulsion and dispersed systems, theory and application of surfactants, new developments in olfactive research, aerosol technology and selected aspects of analytical chemistry.