Effect of low-concentration sodium lauryl sulfate on human vulvar and forearm skin. Age-related differences

The reactivity of forearm and vulvar skin to low-concentration sodium lauryl sulfate (SLS) was studied in 20 healthy women, 10 before and 10 after menopause. SLS at concentrations of 0.1%, 0.5% and 1.0% was applied to the forearm and labium majus for 24 hours. Skin changes were monitored with transepidermal water loss (TEWL), capacitance (CAP) (as an indicator of stratum corneum hydration) and visual scoring (VS). In forearm skin, irritant dermatitis developed in most subjects, as indicated by a VS and TEWL increase, with the reaction in premenopausal women significantly more intense than in postmenopausal women. In vulvar skin, however, irritant reactions were not observed. CAP increased significantly in the forearm of premenopausal but not postmenopausal women, whereas it decreased significantly in postmenopausal vulvar skin. Thus, vulvar skin was less reactive to SLS at low concentrations than was forearm skin. However, SLS did affect vulvar skin stratum corneum hydration. The irritant response in the forearm decreased with age for all parameters studied, whereas in vulvar skin age-related differences in irritant reaction were limited to stratum corneum hydration.