Time course of occlusive effects on skin evaluated by measurement of transepidermal water loss (TEWL). Including patch tests with sodium lauryl sulphate and water.

The time course for transepidermal water loss (TEWL) for a period of 3 h after removal of occlusive patch tests with sodium lauryl sulphate (SLS), water and empty chambers was studied in healthy volunteers. Patches were applied to the upper arm for 24 h. TEWL was measured immediately after removal of the patches, and every 30 min up to 3 h. For SLS and water patches, TEWL remained significantly increased for 3 h, as compared to normal adjacent skin, while for empty chamber patches, TEWL was only significantly increased for 30 min. A significant decrease from 0 to 30 min and from 30 to 60 min was observed for all patches, and for water patches, a significant decrease in TEWL was found from 60 to 180 min, while SLS patches remained constant. The prolonged increase in TEWL observed after SLS exposure is a well-known occurrence. The prolonged increase in TEWL after exposure to water is interpreted as transient damage to the water barrier of the skin.