Sunscreen testing using the mouse ear model.

During the developmental stages of sunscreen formulation it is desirable to have a simple, accurate and inexpensive biological model to test product effectiveness. Another desirable attribute is a quantitative, unbiased response endpoint for evaluation. We have developed such a test system based upon the ear swelling response of hairless albino mice. With this system, irradiation times are greatly reduced; furthermore, the response parameter is metric and can be determined noninvasively with an inexpensive micrometer. Protection factors determined with the mouse ear model show high correlation with the sun protection factors as determined on human subjects (r = 0.92) and were linearly related over a wide range of values. This new method affords a simple, accurate and inexpensive system for evaluation of efficacy and safety of new products.