Interlaboratory validation of the in vitro eye irritation tests for cosmetic ingredients (9). Evaluation of cytotoxicity test on HeLa cells

The cytotoxicity test using MTT on HeLa cells (HeLa-MTT) was evaluated as a n alternative method to the Draize eye irritation test(Draize test) by six to eight laboratories. The 50% inhibition concentration (EC50) for MTT redu ction was calculated. A total of thirty-nine test chemicals were examined. The average interlaboratory coefficient of variation (CV) of the present as say was 25%. Comparison of the in vitro test results with those of the Drai ze test revealed a correlation coefficient of -0.799 between the log(EC50) value and the maximum average total score (MAS) for a 10% solution or suspe nsion. The following characteristics of HeLa-MTT have become apparent throu gh this validation: (1) HeLa-MTT could be applied to all substances includi ng water-insoluble substances, esters, a colour additive, and a substance w hich is known to directly reduce MTT; (2) there is good interlaboratory rep roducibility and strong correlation between HeLa-MTT and Draize MAS; (3) re sults for strong acids, alkanolamines and alcohols (lower mono-ol) clearly deviate from other samples with respect to the correlation between HeLa-MTT and Draize MAS. These results suggest that HeLa-MTT may be useful for pred icting the Draize MAS if definite criteria can be established for applicabl e compounds. (C) 1999 Elsevier Science Ltd. All rights reserved.