Application of in vitro Monolayer and Three-Dimensional Culture Systems to Evaluate the Irritancy of Cosmetic Constituents

Background: For testing skin irritancy, many cytotoxicity tests have been carried out and evaluated. It is evident that human subjects cannot be used as the initial experimental subjects. Therefore, several models, including monolayer and three-dimensional cultures, have been tested to measure skin irritancy. Objective: This study was done to compare several alternative in vitro methods used for evaluating the irritancy of cosmetic constituents. Methods: Cytotoxicity was measured by checking ED50 values with the MTT assay. The irritancy ranking of the five irritants was analyzed using the ED50 values. Results: In terms of irritancy ranking, good correlations were obtained between the monolayer and three-dimensional culture systems, although the concentrations of irritants needed to obtain the ED50 values differed considerably. Conclusion: These findings suggest that caution is necessary in the evaluation of the results of such tests, because the concentration of irritants needed to obtain the ED50 values may differ depending on the culture model used.