Cutaneous differences between Black, African or Caribbean Mixed-race and Caucasian women: biometrological approach of the hydrolipidic film

Background/purpose: Studies about the adaptation of ethnic types of skin to an environment radically different from their original environment are rarely found in the literature. We have evaluated the differences in the skin surface properties of three ethnic groups: Black, African or Caribbean Mixed-race and Caucasian women living in defined climatic conditions. Methods: Biometrological evaluations of barrier function were made by measurements of transepidermal water loss (TEWL), skin hydration and skin dryness. To approach the skin protective coating we evaluated cutaneous lipid index (LI), cutaneous pH, skin frictional properties and skin wettability. Results: The TEWL, cutaneous hydration, dryness and LI show no significant difference. Volunteers were given a self-assessment questionnaire regarding their hygiene and cosmetic practices. The results show that 100% of Black and 92% of African or Caribbean Mixed-race women use a hydrating product daily vs. only 16% of Caucasian women. They justify this practice by the 'dry skin' sensation that they feel if they do not use a moisturizer. We tried to assess objectively to the protective coating surface of the human skin: the hydrolipidic cutaneous film, by measurements of pH, frictional properties and wettability which show significant differences. We may suppose that the hydrophilic/lipophilic balance of the skin in these three ethnic groups is different. Conclusion: To interpret these results as accurately as possible, it would be interesting, in future investigations on the ethnic types of skin, to evaluate the sweat secretion, and to analyse each element of the sebaceous secretions quantitatively as well as qualitatively.