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 testing method, however, we noticed changes that occur in the expression of antigens CD86 and CD54 localized on the surfaces of Langerhans cells activated by antigens. Working with the cosmetics company Shiseido Co., Ltd., we began developing a skin sensitization test method in 2003 that makes use of cultured cells. Similarly, eye irritation is another important consideration when assessing product safety. Using cultured cells taken from the cornea, we developed a short-time exposure test. Comparing the results of this quick test with existing eye irritation data, we found a high degree of correlation.

Because they are simple, convenient, and have high predictivity, these tests can be applied as screening methods to ascertain whether or not a given chemical substance will cause an allergic reaction on the skin or irritation to the eye. Working jointly with cosmetic companies and research institutes both in Japan and abroad, we are actively engaged in getting these tests internationally accepted as standard procedures.