Influence of Repeated Exposure to Surfactants and Solubilizers on the Human Skin, Evaluated by Transepidermal Water Loss and Visual Scoring

Summary

The purpose of this study was to develop a new model for the induction of chronic irritant dermatitis. Such a model enables us to test the irritating potency of various weak toxic agents and to study the interindividual variation in susceptibility to these agents. Also, by this model, it should be possible to determine the sensitivity of transepidermal water loss (TEWL) measurements compared with visual scoring in respect of the detection of early skin changes. Therefore, 11 widely used surfactants and solubilizers were applied to the skin of the forearms of healthy volunteers in aqueous solutions of 12.5 mmol per liter for 45 min twice daily for 3 weeks. The effect on the skin was evaluated daily by means of TEWL measurements and by a visual scoring system. Each solution caused an increase in TEWL value over time due to the cumulative irritating action on the epidermal barrier. This increase in TEWL was different for the various solutions. Thus, it was possible to rank the agents according to irritating potency. This ranking order was the same in each individual and remained constant during the 3 weeks. There was a large interindividual variation in susceptibility to the agents. The TEWL value after 4 days of exposure to sodium laurylsulphate is highly correlated to the baseline TEWL value (r = 0.71). In comparison with the visual scoring system, the TEWL measurements were more sensitive in the detection of early changes in the skin.