SURFACTANT-INDUCED SKIN IRRITATION AND SKIN REPAIR - EVALUATION OF THE ACUTE HUMAN IRRITATION MODEL BY NONINVASIVE TECHNIQUES

Background: Although the induction of irritant dermatitis by surfactants has been extensively studied in recent years, our understanding of the repair phase of irritant dermatitis is limited. Objective: We investigated qualitative and quantitative differences in surfactant-induced irritant skin reactions from short-term exposure to three structurally different surfactants. Methods: Sodium lauryl sulfate (SLS), dodecyl trimethyl ammonium bromide (DTAB), and potassium soap were the model irritants. Surfactant solutions (0.5%) were applied for 24 hours to the volar aspect of the forearm of 11 volunteers. Irritant reactions were assessed until complete healing was indicated by visual assessment and by various aspects of skin function, that is, transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum corneum hydration (electrical capacitance). Results: SLS and DTAB induced similar degrees of erythema, whereas SLS induced a significantly higher TEWL increase. Although both erythema and TEWL were highest 1 hour after exposure to surfactants, skin dryness was a symptom with delayed onset, justifying the long observation period in this study. Minimum hydration values were measured as late as 7 days after surfactant exposure. Dryness was significantly more pronounced in areas exposed to SLS than in areas exposed to DTAB. Complete repair of the irritant reaction induced by either SLS or DTAB was achieved 17 days after surfactant exposure. Stratum corneum hydration was the last feature to return to baseline values. Potassium soap did not significantly influence any skin function. Conclusion: We emphasize the importance of extended periods needed before a patient with irritant contact dermatitis can be reexposed to irritant substances. The evaluation of the irritation potential of diverse surfactants depended significantly on the feature (erythema vs hydration and TEWL) measured.