Genetic effects of benzene and radiation in ICR and X Gf mice

X Gf mice (a tumor-resistant strain) were compared with ICR mice (moderately tumorsensitive) for their sensitivity to chromosomal damage caused by benzene, cyclophosphamide (CP), benzo(a)pyrene (BP) and radiation. There was no difference between strains in the level of micronucleus formation caused by BP, CP or radiation. Although X Gf mice metabolized somewhat less of the dose of benzene per weight than ICR mice, and had some-what higher levels of genetic damage, it is not known whether X Gf mice would be measurably more resistant to benzene carcinogenicity. Short-term genotoxicity tests are used as indicators of initiation, therefore, equal sensitivity to a set of standard clastogens suggests that tumor resistance in X Gf mice is a function of later stages of carcinogenesis.