A proposal for a new in vitro method for direct classification of eye irritants by cytotoxicity test - Preliminary study

None of the in vitro method are suitable for directly classifying of a substance as an eye irritant (category 2). They can classify substance as category 1 (serious eye damage) or as no category (not requiring classification). The aim of this study was to develop a new method for direct classification of a substance as category 2. Cytotoxicity Assay to Assess Eye Irritation (CEI) was performed on fibroblast - HDFn cell line with 36 substances. 5 concentrations of all substances and neat substances were applied directly to the cells. After 30 min, medium was added and cells were incubated at 37 degrees C. The next day, the cytotoxicity assay was performed (MTT assay in the first run and NRU assay in the second run). Based on viability and IC50 value (concentration with 50 % viability) a substance could be classified in category 2, category 1, and as no category. The results obtained were referred to ECHA database. This new method had high sensitivity (53.8-88.9 %), specificity (73.9-100.0 %) and accuracy (69.4-88. 9 %) in the classification to all categories. It effectively classifies not only substances in category 2 but also in category 1 and substances that do not require classification. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

None of the existing in vitro methods are suitable for directly classifying a substance as an eye irritant category 2. The study aimed to develop a new method, Cytotoxicity Assay to Assess Eye Irritation (CEI), which showed high sensitivity, specificity, and accuracy in classifying substances into different categories.