The Short Time Exposure (STE) assay, developed by Kao Corporation (Japan), is an in vitro assay used to assess acute eye irritation potential as an alternative to the traditional in vivo Draize test. The test method evaluates the cytotoxicity induced by a series of test chemical dilutions in a monolayer of rabbit corneal fibroblasts (Statens Seruminstitut Rabbit Cornea – SIRC) after a single five-minute exposure.
Two prediction models were initially developed for the STE assay — one categorizes the test material as either “Non-Categorized” material or a GHS Category 1 Irritant; the second provides a rank classification of ocular irritation (minimal, moderate or severe). The prediction models are based on the viability of a 5% and 0.05% dilution of the test material relative to solvent controls. The first approach may be used to identify test substances and mixtures that induce serious eye damage as well as those that do not require classification for either serious eye damage or eye irritation, as defined by the United Nations (UN) Globally Harmonized System of Classification and Labeling of Chemicals (GHS), as described in OECD Test Guideline 491. The potency assessment may be useful for supporting test material screening or product development and characterization goals.