The TI value of surfactant. The TI value on the vertical axis indicates the relative value of the effect on the skin barrier function with water as the standard (TI = 1). Values represent mean and standard error (SE) obtained from 4 or more experiments. 1: Sodium laurate, 2: Sodium lauryl sulphate, 3: Dimethyldistearylammonium chloride, 4: Trimethylstearylammonium chloride, 5: Lauryl Dimethylaminoacetic acid betaine, and 6: Cocamidopropyl betaine. (*) is the quaternary ammonium salt type surfactant.