Interlaboratory validation of the in vitro eye irritation tests for cosmetic ingredients. (10) Evaluation of cytotoxicity test on CHL cells

The present interlaboratory validation study was performed in order to eval uate the use of Chinese hamster lung cell lines that employs crystal violet staining (CHL-CVS) as an alternative cytotoxicity test to the Draize eye i rritation test (Draize test) for cosmetic ingredients. Ten substances, nine of which were surfactants, were evaluated at seven laboratories in the fir st phase of the validation study; 15 substances including dyes and lipids w ere evaluated at seven laboratories in the second phase of the validation s tudy; 14 substances including acids and alkalis were evaluated at four labo ratories in the third phase of the validation study. The logEC(50) values o btained for CHL-CVS were compared with the maximal average Draize total sco re (MAS) for a 10% (w/v) solution of 38 cosmetic ingredients as well as iso tonic sodium chloride solution. The interlaboratory coefficient of variatio n (CV) for EC(50)s was 35.6%, which was considered to be within a tolerable range. The correlation coefficient and the Spearman's rank correlation coe fficient between the in vitro and in vivo tests were -0.729 and 0.709, resp ectively. The prediction ability of the proposed method was assessed from t he linear regression line for a MAS cut-off point of 15. According to this analysis, four substances (two alcohols and two acids) were determined to b e false negative. The present study revealed the following characteristic f actors of this method: (1) CHL-CVS could be applied to all the test substan ces including dyes and lipids in this study; (2) The results for medium-ins oluble substances varied according to the laboratory; (3) The correlation b etween the in vivo and in vitro data for acids and alcohols (lower mono-of) differed from that of the other substances. These results suggested that t he CHL-CVS might have a potential to predict the Draize MAS if definite cri teria can be established for the compounds to be applicable. (C) 1999 Elsev ier Science Ltd. All rights reserved.