Impact of water exposure on skin barrier permeability and ultrastructure

Background: Skin occlusion caused by the use of diapers or sanitary napkins often results in irritant contact dermatitis. Furthermore, prolonged occlusion and exposure to body fluids are known to increase skin hydration and permeability, thus leading to irritant contact dermatitis. Objective: To investigate the effects of water exposure on the skin and its barrier functions, in order to obtain more insights into the mechanisms of irritant contact dermatitis. Methods: Water patches were applied to the volar forearm skin of 10 human subjects for 3 hours. Permeability of the stratum corneum (SC) was examined with methyl nicotinate (MN). Alterations in the hydration and ultrastructure of the SC were measured with Raman spectroscopy and multiphoton microscopy, respectively. Results: Water profiles found with Raman spectroscopy showed notable increases in water content throughout the SC and skin surface. Multiphoton microscopy showed morphological changes in the intercellular space of the SC. Emerged pools seemed to contribute to increased MN absorption. Conclusion: Excessive skin hydration leading to changes in the SC ultrastructure might result in increased skin permeability to skin irritants and allergens.