Prediction models for eye irritation potential based on endpoints of the HETCAM and neutral red uptake tests

The aim of this study was to explore the possibility of distinguishing between eye irritants (I; EU risk phrases R36 and R41) and nonirritants (NI), by using in vitro endpoints of the hen's egg test on the chorioallantoic membrane (the HETCAM test) and the neutral red uptake (NRU) test. Prediction models were derived by applying binary logistic regression to the in vitro data for these endpoints, which were taken from the report of a German validation study on the use of the HETCAM and 3T3 NRU tests as alternatives to the Draize eye irritation test. Whereas the validation study led to the conclusion that the combined use of the two tests enables a satisfactory discrimination between severe (R41) and nonsevere (NI, R36) eye irritants, the results of the present study indicate that the two in vitro tests can also be used to discriminate between nonirritants (NI) and irritants (R36 and R41).