Suitability of histopathology as an additional endpoint to the Isolated Chicken Eye Test for classification of non-extreme pH detergent and cleaning products

- Development and testing of histopathological criteria as additional endpoint to ICE.
- Predictivity of histopathology to identify GHS Cat. 1 non-extreme pH detergent & cleaning products.
- Mechanistic insights on non-extreme pH detergent and cleaning products ocular effects.
- Identification of serious eye damage caused by persistent/irreversible tissue effects.
- Comparison between in vitro versus additivity approach eye hazard classification.

A.I.S.E. investigated the suitability of histopathological evaluations as an additional endpoint to the regulatory adopted ICE in vitro test method (OECD TG 438) to identify non-extreme pH detergent and cleaning products that require classification as EU CLP/UN GHS Category 1 (serious eye damage). To this aim, a total of 30 non-extreme pH products covering the range of in vivo classifications for eye irritation, and representing various product categories were tested. Epithelium vacuolation (mid and lower layers) and erosion (at least moderate) were found to be the most relevant histopathological effects induced by products classified in vivo as Category 1. Histopathology criteria specifically developed for non-extreme pH detergent and cleaning products were shown to correctly identify materials classified as Category 1 based on in vivo persistent effects, and to significantly increase the overall sensitivity of the standard ICE prediction model for Category 1 identification (to 75%) whilst maintaining a good concordance (73%). In contrast, use of EU CLP additivity approach for classification of mixtures was considerably less predictive, with a concordance of only 27%, and 100% over-predictions of non-Category 1 products. As such, use of histopathology as an addition to the ICE test method was found suitable to identify EU CLP/UN GHS Category 1 non-extreme pH detergent and cleaning products and to allow a better discrimination from Category 2 products.