236 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 8 L F 1 F 0 ? i':. ?i"" :.: :.. ß ß ß . :.. ..... Cheeks Legs Blacks Whites Figure 5. pH (mean + SD). Asterisk indicates significant difference (p 0.05). The lower rates of capacitance increase on the forearms and legs in blacks is further evidence of a better skin barrier. However, our results on the forearms and legs are in conflict with other studies that have shown water content to be higher in blacks (7,15). Regional differences and especially the degree of photodamage may explain some of the divergent results. There is evidence of a more elaborate superficial vasculature in the facial skin of blacks as well as more apocrine and mixed eccrine-apocrine glands (17). All these factors might explain why black facial skin appears to be more hydrated as compared to white skin. 0.2 0.16 0.12 0.08 0.04 Cheeks Forehead Legs Blacks i Whites i ._a 4 4 Figure 6. Desquamation index (mean -+ SD). Asterisk indicates significant difference (p 0.05).

COMPARISON OF BLACK AND WHITE SKIN 237 ! 2.5 L 1.5 1 ..,•.. o.s 0'" Face Forearms Legs Blacks Whites Figure 7. Visual dryness (mean + SD). Asterisk represents significant difference (p 0.05). On the other hand, in the volar forearm and the outer aspects of the legs, which are not as sun-exposed as the face, white skin had a higher water content. Possible reasons may be the lower density of sweat glands per cm 2 on the forearms and legs as compared to the face (18) and the greater number of corneocyte cell layers in black skin such that superficial corneocytes are older and looser in the desquamating portion of the horny layer. It is now appreciated that intercellular lipids contribute to the water-retention properties of the skin. Ceramides, which constitute about 50% of the stratum corneum lipids, are chiefly responsible for the water-retaining properties of the stratum corneum. 6 • . • 1 L ? o ? BL.ACKS WHITES Cheeks Forehead Figure 8. Density of P. acnes (mean q- SD).