Developing Safety Tests without the Use of Animals
Safety Science

In developing safety assessment methods for our products and materials, Kao utilizes cultured cells so that no animal is used. For example, skin allergies are complex mechanisms affecting the entire body, and they involve many stages. Langerhans cells in the epidermis are activated by an antigen and migrate to local lymph nodes, triggering the proliferation of antigen-specific T lymphocytes. If the skin comes into contact with the antigen for a second or subsequent exposure, it will become locally inflamed. In conventional skin sensitization tests, all of these complex reactions are reproduced in the body. In developing a new skin sensitization testing method using cultured cells, however, we noticed changes that occur in the expression of antigens CD86 and CD54 localized on the surfaces of Langerhans cells activated by antigens. Furthermore, working with the cosmetics company Shiseido Co., Ltd., we began developing the human Cell Line Activation Test (h-CLAT) in 2003 that makes use of cultured cells. We have been aggressively collaborating with cosmetic companies and research institutes in Japan and overseas to establish the h-CLAT as a global standard for a skin sensitization test. Finally, the h-CLAT was globally adopted as the OECD*1 Test Guideline (OECD TG 442E) in July 2016.

Similarly, eye irritation is another important consideration when assessing product safety. Using cultured cells taken from the cornea, we developed the Short Time Exposure (STE) test. Comparing the results of this test with existing eye irritation data, we found a high degree of correlation. The STE test has been undergoing international review by relevant public authorities and acquiring reliability as a safety test. Then, the STE test was also globally adopted as the OECD Test Guideline (OECD TG 491) in July 2015, which is a new cell-based eye irritation alternative test capable of predicting chemicals classified non-irritation and severe irritation in the Globally Harmonized System.

*1 OECD:Organization for Economic Co-operation and Development