Correlation and validation of alternative methods to the Draize eye irritation test (OPAL project)

A multicentre study of alternative methods to the Draize eye irritation test, involving six different laboratories was organized by OPAL (Oeuvre Pour l'Assistance aux Animaux de Laboratoire). Forty chemicals (including solvents, surfactants, acids, bases, and others) were selected for testing by three methods, namely Griffith's test (a low-volume eye irritation test on rabbits), the hen's egg chorioallantoic membrane (HET-CAM) assay for the evaluation of hyperaemia, haemorrhage and coagulation, and neutral red uptake by SIRC cells for the assessment of cytotoxicity. Each method was used in two or three laboratories. Intralaboratory reproducibility was good for each laboratory with values, for error, close to 10%. Interlaboratory agreement was also good, particularly for the cell culture method, a quantitative and objective technique. Griffith's test correlated well with the Draize test (r = 0.846; n = 37), while for the HET-CAM test (r = 0.670; n = 32) and the cell culture method (r = 0.579; n = 32) the correlation was satisfactory. A more complete statistical analysis is currently under way to confirm and extend these preliminary findings.