Long-term effect of benzene in C57BL/6N mice.

Weaning male C57BL/6N mice received repeated subcutaneous injections of benzene in corn oil for 54 weeks. These mice and surviving controls were killed 104 weeks after the first injection. There was no evidence of carcinogenic activity in benzene-injected mice. A high incidence of amyloidosis developed in mice of all treated and untreated groups. Butyinitrosourea, used as a positive control, induced lymphomas or leukemias (in most exposed mice) and intestinal tumors in a few.