Suppression of 7,12-dimethylbenz[a]anthracene-induced chromosome aberrations in rat bone marrow cells after treatment with Sudan III and related azo dyes.

Noninbred Long-Evans rats fed Sudan III at 24 hours before they were given an injection of 7,12-dimethylbenz[a]anthracene (DMBA) displayed prominently suppressed DMBA-induced chromosome aberrations (CA) in their bone marrow cells. Rats fed Sudan III simultaneously with the DMBA injection showed no suppressed CA effect. The suppressive effect of Sudan III on DMBA-induced CA paralleled the dose rate of Sudan III when given in the range between 1 and 10 mg Sudan III/kg body weight; higher doses produced no additional suppression. The capacity of various Sudan III-related chemicals to prevent DMBA-induced CA paralleled their capacity to prevent DMBA-induced adrenal apoplexy and mammary cancer. Among the azo dyes investigated, Sudan III was most efficient in protecting against DMBA-induced CA. Polychlorinated biphenyl and phenobarbital, inducers of drug-metabolizing enzymes, also suppressed DMBA-induced CA.