Interlaboratory validation of the in vitro eye irritation tests for cosmetic ingredients. (1) Overview of the validation study and Draize scores for the evaluation of the tests

A three-step interlaboratory validation of alternative methods to the Draiz e eye irritation test (Draize test) was conducted by the co-operation of 27 organizations including national research institutes, universities, cosmet ic industries, kit suppliers and others. Twelve alternative methods were ev aluated using 38 cosmetic ingredients and isotonic sodium chloride solution . Draize tests were conducted according to the OECD guidelines using the sa me lot of test substances as was evaluated in the alternative tests. Result s were as follows. (1) Variation in Draize scores was large near the critic al range (maximal average Draize total scores (MAS) = 15-50) for the evalua tion of cosmetic ingredients. (2) Interlaboratory variation was relatively small for the alternative tests. The mean coefficients of variation (CV%) w ere less than 50 for all assays except for the hen's egg-chorioallantoic me mbrane test (HET-CAM), chorioallantoic membrane-trypan blue staining test ( CAM-TB) and haemoglobin denaturation test (HD). The CV% of these three meth ods came into the same range as the other tests when non-irritants were exc luded from the data analysis. (3) Results for acids (pH of 10% solution <2. 5), alkalis (pH of 10% solution > 11.5) and alcohols (lower mono-ol) in cyt otoxicity tests clearly deviated from the other samples in the comparison o f cytotoxicity with Draize results. (4) Pearson's correlation coefficients between results from cytotoxicity tests using serum and MAS were -0.86 to - 0.92 For samples excluding acids, alkalis and alcohols. (5) When the sample s were divided into liquids and powders. r of CAM-IB increased from 0.71 fo r all samples to 0.80 and 0.92, respectively. (6) Spearman's rank correlati on coefficients between the results of alternative methods and MAS were rel atively high (r>0.8) in the case of MET-CAM and CAM-TB. Those for cytotoxic ity tests were high if the data for acids. alkalis and alcohols were exclud ed (SIRC-CVS: r = 0.945, SIRC-NRU: r = 0.931, HeLa-MTT: r = 0.926, CHL-CVS: r = 0.880). Exclusion of data for powdered samples also increased the coef ficient of MET-CAM and CAM-TB to 0.831 and 0.863, respectively. These resul ts suggest that no single method can constitute an evaluation system applic able to all types of test substances by itself. However, several methods wi ll be useful for the prediction of eye irritation potential of cosmetic ing redients if they are used with clear understanding of the characteristics o f those methods. (C) 1999 Elsevier Science Ltd. All rights reserved.