Performance of the pollen tube growth test in the COLIPA validation study on alternatives to the rabbit eye irritation test

In the present paper, we describe and analyse the performance and the resul ts of the pollen tube growth (PTG) test applied to the COLIPA international Validation study of in vitro alternatives to the Draize eye irritation tes t. The PTG test, based on photometric quantification of in vitro pollen tub e mass production, was used by three independent laboratories to estimate t he acute eye irritation potentials of 23 ingredients and 32 cosmetic formul ations. Basing on historical Draize test data and on IC50 values of previou sly tested cosmetic formulations, a mathematical formula was generated to p redict rabbit eye irritation potentials from PTG test results. Statistical evaluation of the calculated modified maximal average scores (MMAS) reveale d a high prediction capability of the PTG test in regard to the finished fo rmulations but a relatively low one for alcohols, higher concentrated catio nic surfactants, and acidic and alkaline materials. Furthermore, our result s indicated that the PTG test was able to produce precise IC50 values witho ut any limitations from all of the 55 test substances with good intra- and interlaboratory reproducibility. From these findings we suggest that the PT G test is not a validated test at present but is considered to be a potent candidate for further validation processes. For this purpose an additional prediction model for ingredient classes as mentioned above must be generate d. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.