IRAG WORKING GROUP 2 - CAM-BASED ASSAYS

CAM-based assays, in which test material is applied to the chorion all antoic membrane (CAM) of embryonated chicken eggs, were assessed as al ternatives to the Draize eye irritation test. Two general types of CAM -based assays are currently in use, the HET-CAM test and the CAMVA ass ay. Evaluations were made of five data sets produced with three differ ent modifications of the HET-CAM test and two data sets obtained with the same CAMVA protocol. Data sets consisted of 9-133 test chemicals, usually from the sponsor's product line, and also from a validation tr ial. Each data set and assay protocol were analysed for quality of dat a, purpose and proposed use of the assay, range of responses covered, range of test materials amenable, current use in safety and risk asses sment both in-house and for regulatory purposes. Since the MMAS Draize score was not available for all in vivo data sets, the Sigma MMMIS, w hich correlates well with the MMAS, was used instead. In vitro/in vivo correlations calculated with Pearson's linear coefficient ranged from r = 0.6 to r = 0.9 for six of seven data sets. Corneal opacity and in flammation of the iris showed the best correlation to in vitro data. P rediction rates were significantly improved when partial linear regres sion was used, and the predictivity of three different HET-CAM protoco ls was almost the same. HET-CAM assays showed the best prediction with surfactants and surfactant-based formulations, whereas the CAMVA assa y provided the best performance with alcohols. (C) 1997 Elsevier Scien ce Ltd.