Sunscreen Efficacy Against UVA1- And Visible Light-Induced Skin Pigmentation Is Influenced by Ancestry.

BACKGROUND

There is growing evidence that individuals with different skin phototypes require tailored approaches to achieve optimal photoprotection. Individuals with darker skin phototypes are more prone to UVA1- and visible light-induced pigmentation, whereas lighter phototypes are more susceptible to shorter wavelengths such as UVB and UVA2. Thus, skin phototype is an important determinant of sunscreen efficacy. In the present study, we have asked if ancestry-independent of phototype-is another factor affecting sunscreen efficacy.

OBJECTIVES

(i) To determine the overall photoprotective effects of two sunscreen formulations against UVA1, visible light (VL), and combined visible light plus UVA1, and (ii) to compare the photoprotective efficacy of both products between Han Chinese participants and participants of European ancestry.

METHODS

Forty healthy volunteers (N = 20 Han Chinese; N = 20 of European ancestry), matched for phototype, constitutive pigmentation, gender, and age, were exposed to VL, UVA1, and combined VL plus UVA1 to induce pigmentation responses following standardized irradiation protocols. Skin responses across treated and untreated sites were analyzed using linear mixed-effects models.

RESULTS

Across all participants, both sunscreen formulations provided significant protection against VL, UVA1, and combined VL plus UVA1. Notably, photoprotective efficacy against UVA1-induced immediate (IPD) and persistent pigment darkening (PPD) differed significantly between individuals of different ancestries, with one formulation showing stronger protection in Han Chinese.

CONCLUSION

This exploratory study indicates that sunscreen efficacy may differ across ancestries. Thus, sunscreens should not only be tailored to different phototypes but also need to consider ancestry-related factors.