Development of a defined approach for eye hazard identification of solid chemicals according to the three UN GHS categories

Currently two OECD adopted defined approaches (DA) for eye hazard identification of non-surfactant liquids exist (OECD TG467). The purpose of the current study was to develop a DA for eye hazard identification according to the three UN GHS categories (Cat.1, Cat. 2, No Cat.) for solid chemicals: the DAS. The DAS combines two test methods described in OECD TG437 and TG492. The DAS was developed based on in-depth statistical analysis of a database on solids for which in vitro and historically curated in vivo Draize eye test data exist. The performance of the DAS was assessed by comparing the predictions with the classification based on in vivo Draize eye test data, on the one hand, and with the performance criteria established by the OECD expert group, on the other hand. In a first tier of the DAS, the SkinEthic™ HCE EIT method (TG492) is used to distinguish No Cat. from classified substances. For classified substances the BCOP LLBO method (TG437) is used to identify Cat. 1, the remaining solids are predicted Cat. 2. In summary, 77.4% Cat. 1 (N=31), 52.3% Cat. 2 (N=18) and 70.0% of No Cat. (N=60) solids were correctly identified compared to the classification based on the Draize eye test. The percentage of correct predictions met the minimum OECD established performance values of 75% Cat. 1, 50% Cat. 2, and 70% No Cat. and the percentage of mispredictions was below the established maximum values. Therefore, inclusion of the DAS in OECD TG 467 has been achieved. Plain language summaryDefined approaches combine information from different non-animal testing methods in a specific combination and interpret the results according to a fixed procedure. Such defined approaches are already available as full replacements of animal testing to assess the eye hazard of liquid chemicals (OECD Test Guideline 467). This study used two OECD-adopted in vitro methods, based on human cells and corneas from cattle, to create a defined approach that can be used for solid chemicals. The performance of the procedure was assessed against data from previous animal tests for 109 solid chemicals. The results have already led to this defined approach being adopted by the OECD TGs programme for inclusion in TG 467. With the adoption of the new DA, non-animal human relevant strategies are now available for eye hazard assessment of liquids and solids, reducing the need for animal testing.