Wash test method: Hannuksela and Kinnunen1 developed a wash test method to determine the effect of moisturizers in preventing irritant contact dermatitis (ICD). Twelve healthy female students washed the outer aspects of their upper arms with a liquid dishwashing detergent for one minute twice daily for one week. Eight commercial moisturizers were applied to the left upper arm just after each washing while the other arm was left untreated. During the second week, the left upper arm only was treated with the moisturizers twice daily.
Transepidermal water loss (TEWL) was found to increase during the washing period by 13 g/m2/hr in the untreated arm, while the increase in the treated areas was only 3 g/m2/hr. Further, visible dermatitis appeared on the untreated arm while the treated areas remained objectively and subjectively free from symptoms and signs. Blood flow also increased significantly in the washed, untreated arm, but did not change in the arm treated with moisturizers.