Clinical Skin Mildness Evaluations of Direct and Indirect Exposure to Two Commercial Laundry Detergents with Markedly Different pH Designed for Sensitive Skin Using a Hand-Laundering Model.

The skin mildness of two commercial laundry detergents designed for sensitive skin, Tide Free and Gentle^® (TFG) versus All Free Clear^® (AFC), was compared in clinical studies, and the role of marked product pH differences was assessed. Two double-blind randomized human studies were conducted. Study 1 was a 1-day repeat insult forearm test, in which four exposures to solutions of TFG or AFC were performed to mimic direct exposure to dilute detergent during hand-laundering. Corneometer, erythema and dryness grading, transepidermal water loss (TEWL), and skin surface pH evaluations were carried out. Study 2 was a 21-day arm patch test of fabrics washed with TFG or AFC to mimic indirect contact to skin of detergent residues, with erythema grading. Separately, pH and reserve alkalinity were determined for each detergent. In Study 1, TFG was significantly milder than AFC in all measures except TEWL (no significant difference). In Study 2, the detergents were approximately equivalent in erythema grading. Analysis showed AFC was substantially more alkaline (pH 10.8) than TFG (pH 7.9) with higher reserve alkalinity. TFG was significantly milder than AFC in Study 1, which may be due in part to the increased skin surface pH seen with direct exposure to AFC's high alkalinity.