Itagaki, H., M. Sugiyama, T. Ashikaga, M. Hoya, Y. Katsumura and S. Kato. A Tiered in Vitro Evaluation System to Predict Eye Irritancy and Skin Irritancy of Cosmetic Ingredients. ATLA 1999. 27: 348.

In Japan, the guidance on alternative appraisal methods for determining the eye irritation potential of cosmetic ingredients has been prepared. The guidance indicates that, if a test substance is not formulated in the products at a concentration in excess of 10%, it is classified as a non-irritant without animal tests and is not considered cytotoxic. However, it is difficult to accurately evaluate water-insoluble ingredients or cosmetic products, with the conventional cytotoxicity tests. Kits of three-dimensional tissue equivalents seem to be effective in solving this problem. Stable supply of kits should be considered. We have constructed in a tiered evaluation system for eye irritancy and skin irritancy of cosmetic ingredients using two in vitro assays: a collagen gel system constructed from collagen and human dermal fibroblasts; and the crystal violet staining assay using SirC cells. The latter has been validated as an alternative to the eye irritation test in two validation studies supported by both a Ministry of Health and Welfare (MHW) project and a Japanese Society for Alternatives to Animal Experiments (JSAAE) project. This tiered evaluation system could be applicable for each category of cosmetic ingredients, regardless of their water solubility. Classification of irritancy of cosmetic ingredients obtained from this tiered evaluation system correlated fairly well with the accumulated in vivo results of both eye irritation and skin irritation. These results suggest that this tiered evaluation system will also be applicable to cosmetic products.