Outdoor clinical testing with reference sunscreens to determine differences in skin response between populations of different ethnicity: A combined data analysis from 128 subjects

BackgroundTwo previously published clinical studies by our group assessed erythema and pigmentation responses in outdoor conditions with three reference sunscreens, comparing their effectiveness under the full spectrum of natural sunlight. These studies followed an almost identical protocol but were conducted in two different locations and in two ethnic groups: broadly, Chinese (Singapore) and White European (Mauritius). We analysed the data from these two study populations to compare differences in skin response according to ethnicity. MethodsThe analysis included 128 subjects (53 were Chinese from Singapore and 75 were White European from Mauritius and Singapore). Products used were the reference sunscreens P3 (sun protection factor [SPF] 15), P5 (SPF 30) and P8 (SPF 50+) from ISO norm 24444:2019. Participants were exposed to outdoor sunlight for 2-3 h, depending on baseline ITA. Endpoints were erythema at 24 h: clinical score and colorimetry (Delta a*) and pigmentation at 1 week based on colorimetry (Delta L* and Delta ITA). ResultsAmong those with baseline ITA > 41, there were differences in erythemal response between the Chinese and White European groups, the White European group being more erythematous and also having a higher rate of photoprotection failure particularly at SPFs 15 and 30. ConclusionDifferences in skin response to sun influenced by ethnicity should be taken into account when making recommendations on sun safety.

Automated summary

This study compared the differences in erythema and pigmentation responses of Chinese and White European individuals to three different sunscreens in outdoor conditions. The findings showed that White Europeans had a higher incidence of erythema response and a higher rate of photoprotection failure, especially with SPF 15 and 30 sunscreens. Therefore, ethnicity should be taken into account when making recommendations for sun safety.