2018 Volume 23 Issue 1 Pages 1-8
The Organization for Economic Cooperation and Development established Test Guidelines (TG) for non-animal testing methods to assess the safety of cosmetic ingredients. TG439 utilizes reconstructed human epidermis to assess skin irritation. TG439 are available for evaluating agents after 4-h exposure, but it is unclear whether those methods can be used to estimate skin irritation after 24-h exposure, which is necessary for evaluating non- or only slightly irritating substances, such as cosmetic ingredients, and for pharmaceutical approval in Japan. In this report, we assessed the performance of the EpiDermTM SIT (skin irritation test) as an alternative method for predicting slight irritation after 24-h exposure. We tested 40 substances listed by the Skin Irritation Test Working Group of the Japanese Society for Alternatives to Animal Experiments. Evaluation of water-soluble substances had 92% accuracy. Evaluation of oil-soluble substances exhibited only 62% accuracy, 18% sensitivity, and 93% specificity. Although the assay produced a high percentage of false-negative results for oil-soluble substances, positive predictivity was high for all substances. A positive result in the EpiDermTM SIT indicates a strong possibility of skin irritation. These results suggest that the EpiDermTM SIT is useful for assessing the potential of substances as irritants after 24-h exposure.