The BALB/c 3T3 NRU test is probably the cytotoxicity test that has been used most frequently in formal validation programs, all of which were aimed at evaluation of cytotoxicity in predicting eye irritancy. Large-scale studies to be mentioned here are Phases I, II, and III of the Cosmetic, Toiletry, and Fragrance Association (CTFA) validation program (Gettings et al., 1991, 1992, 1994a, 1994b);...