A comparison of two cytotoxicity tests for predicting the ocular irritancy of surfactants

In vivo rabbit eye tests have attracted criticism on both scientific and ethical grounds. Consequently, there is a need to develop new approaches that still provide the necessary information on eye irritation hazard but that minimize or even avoid the use of whole laboratory animals. Cytotoxicity models have been used to predict the ocular irritancy of surfactants, since this class of chemicals has an essentially common action on cell membranes which involves membrane disruption. The aim of the present studies was to compare the predictive ability of two in vitro cytotoxicity tests, the K562 and the red blood cell lysis tests, in the assessment of the in vivo eye irritancy of surfactants. The results of these studies on 14 selected surfactant materials showed that the K562 assay was only modestly predictive of the in vivo response, with a specificity of 86% but a sensitivity of only 57%. In contrast, the red blood cell lysis test was more predictive, correctly identifying all irritants tested. In addition, all non-irritant surfactants examined were predicted and a high (89%) ability to rank irritant effect was demonstrated. The red blood cell lysis test could be a powerful addition to a testing strategy or pre-screen for the evaluation of surfactant chemicals.