Global Acceptance of Non-animal Technologies for Evaluating Skin Sensitization

It is especially important to evaluate the skin allergenicity (sensitization) potential of a product’s ingredients because many Kao products come into contact with the skin. Since 2000, we have been developing reliable non-animal technologies for evaluating skin sensitization.

In 2016, we jointly developed an alternative test method called the human cell line activation test (h-CLAT), which focused on skin immune cell functions, with Shiseido Co., Ltd. This method was adopted as a reliable global standard method (OECD Test Guidelines [TG442E]). Recently, we have been focusing on the antioxidative and inflammatory responses that occur in the keratinocytes during the induction phase of skin sensitization and developed an alternative test method called Epidermal Sensitization Assay (EpiSensA). This method predicts a skin sensitization potential of a test chemical which is applied on the surface of the artificial skin model based on marker gene expression responses.
The artificial skin model used in the EpiSensA has a structure similar to human skin, so it can be assessed as if the chemicals were applied to actual skin. This will enable us to assess lipophilic chemicals—which have been a problem with existing alternative test methods—and was approved in 2024 as a global standard method (TG442D) due to having better applicability and predictivity than the existing alternative test methods.
Kao believes that both h-CLAT and EpiSensA will be used widely all over the world and make significant contributions to the development of new chemicals in various industries.

Skin sensitization, a complicated biological phenomenon, can be accurately evaluated by establishing an combination strategy based on multiple results of test methods such as h-CLAT and EpiSensA, that focus on critical cellular responses in the adverse outcome pathway of skin sensitization.
We will cooperate with an international safety collaboration organization, the International Collaboration on Cosmetic Safety, to promote development, standardization, and dissemination of quick and appropriate assessment systems.