Contents lists available at ScienceDirect Toxicology in Vitro journal homepage: www.elsevier.com/locate/toxinvit Reprint of “CON4EI: Bovine Corneal Opacity and Permeability (BCOP) test for hazard identification and labelling of eye irritating chemicals” ☆ Sandra Verstraelen a, ⁎ , Gareth Maglennon b , Karen Hollanders a , Francis Boonen a , Els Adriaens c , Nathalie Alépée d , Agnieszka Drzewiecka e , Katarzyna Gruszka e , Helena Kandarova f , Jamin A. Willoughby Sr. g , Robert Guest b , Jane Schofield b , An R. Van Rompay a a VITO NV (Flemish Institute for Technological Research), Mol, Belgium b Envigo, Cambridgeshire, United Kingdom c Adriaens Consulting BVBA, Aalter, Belgium d L'Oréal Research & Innovation, Aulnay-sous-Bois, France e Institute of Industrial Organic Chemistry Branch Pszczyna, Pszczyna, Poland f MatTek In Vitro Life Science Laboratories, Bratislava, Slovak Republic g Cyprotex US, LLC, MI, USA ARTICLE INFO Keywords: CON4EI Ocular irritation Bovine Corneal Opacity and Permeability (BCOP) OP-KIT Laser Light-Based Opacitometer (LLBO) Histopathology OECD Test Guideline 437 ABSTRACT Assessment of ocular irritation potential is an international regulatory requirement in the safety evaluation of industrial and consumer products. None in vitro ocular irritation assays are capable of fully categorizing che- micals as stand-alone. Therefore, the CEFIC-LRI-AIMT6-VITO CON4EI consortium assessed the reliability of eight in vitro test methods and computational models as well as established a tiered-testing strategy. One of the selected assays was Bovine Corneal Opacity and Permeability (BCOP). In this project, the same corneas were used for measurement of opacity using the OP-KIT, the Laser Light-Based Opacitometer (LLBO) and for histo- pathological analysis. The results show that the accuracy of the BCOP OP-KIT in identifying Cat 1 chemicals was 73.8% while the accuracy was 86.3% for No Cat chemicals. BCOP OP-KIT false negative results were often related to an in vivo classification driven by conjunctival effects only. For the BCOP LLBO, the accuracy in identifying Cat 1 chemicals was 74.4% versus 88.8% for No Cat chemicals. The BCOP LLBO seems very promising for the identification of No Cat liquids but less so for the identification of solids. Histopathology as an additional endpoint to the BCOP test method does not reduce the false negative rate substantially for in vivo Cat 1 chemicals. 1. Introduction Measurement of ocular irritation potential is a necessary step in the safety evaluation of both industrial and consumer products and is therefore part of the international regulatory requirements for the testing of chemicals. The main objective of the CON4EI (CONsortium for in vitro Eye Irritation testing strategy) project (2015–2016) was to develop tiered testing strategies for eye irritation assessment for the most important drivers of classification (Adriaens et al., 2014) to finally replace the in vivo Draize eye test (Draize et al., 1944). The irritation potency of a set of 80 well-characterized chemicals was evaluated using 8 alternative test methods, besides the use of computational models. One of the in vitro assays selected was the Bovine Corneal Opacity and Permeability (BCOP) test method (Gautheron et al., 1992). The BCOP assay is an in vitro alternative which is routinely used in several industrial and con- tract testing laboratories in the context of workplace safety and product safety applications (Vanparys et al., 1993). The assay can be used under certain circumstances and with specific limitations for eye hazard classification and labelling of chemicals and is described in the Orga- nisation for Economic Co-operation and Development Test Guideline (OECD TG) 437 (OECD, 2013a). While it is not considered valid as a stand-alone replacement for the in vivo Draize eye test, the BCOP test method is recommended as an initial step within a testing strategy such https://doi.org/10.1016/j.tiv.2018.03.005 Received 27 March 2017; Received in revised form 30 May 2017; Accepted 27 June 2017 DOI of original article: http://dx.doi.org/10.1016/j.tiv.2017.06.028 ☆ A production error resulted in this article appearing in the wrong issue. The article is reprinted here for the reader's convenience and for the continuity of the special issue. For citation purposes, please use the original publication details; Toxicology in Vitro, Vol 44C, pp. 122-133. ⁎ Corresponding author at: Flemish Institute for Technological Research (VITO NV), Boeretang 200, 2400 Mol, Belgium. E-mail address: sandra.verstraelen@vito.be (S. Verstraelen). Toxicology in Vitro xxx (xxxx) xxx–xxx 0887-2333/ © 2017 Elsevier Ltd. All rights reserved. Please cite this article as: No Author, Toxicology in Vitro (2017), https://doi.org/10.1016/j.tiv.2018.03.005