Differences of skin irritation between Japanese and European women

Background After using cosmetics, Japanese women frequently complain about sensitive, stinging skin. We wondered whether Japanese women's skin is more sensitive than that of Caucasians. Objectives To examine possible racial differences of skin irritation and subjective sensations. Methods We performed patch testing on the forearm with sodium lauryl sulphate (SLS) at different concentrations (0.25%, 0.5%) and 24-h exposure time. Skin reaction was evaluated by measurement of transepidermal water loss (TEWL), stratum corneum hydration, sebum secretion, laser Doppler flowmetry (LD), content of melanin and erythema. During a stinging test with 10% lactic acid (applied to one side of the cheeks) the subjects were asked to describe the present intensity of any sensation. We used a Chromameter to measure skin colour before and after application of lactic acid. This study was performed in Marburg, Germany, with healthy Japanese and German women living in Marburg. Results After SLS testing, we found no significant differences of the barrier function in the stratum corneum, but we found significant subjective sensory differences between Japanese and German women. Conclusions Japanese women may complain about stronger sensations reflecting a different cultural behaviour rather than measurable differences in skin physiology; however, a faster penetration of SLS in Japanese cannot be excluded.