The bone marrow clastogenicity of eight halogenated benzenes in male NMRI mice

Eight widely used halogenated benzenes, including bromobenzene (BB), chlorobenzene (CB), three isomers of dichlorobenzene (DCB) and three isomers of trichlorobenzene (TCB) were tested for acute toxicity (LD50) and clastogenicity in 8-week-old NMRI mice by intraperitoneal administration. Four doses of each chemical (up to 70% of LD50) were tested for clastogenic activity. Each compound was administered in two equal doses, 24 h apart. Increased formation of micronucleated polychromatic erythrocytes, observed in femoral bone marrow, 30 h after the first injection, was considered to be due to the clastogenic activity of the test compound. All the halogenated benzenes tested were found to be clastogenic (P less than 0.01). The highest clastogenic activities were induced by m-DCB and BB. Among the three isomers of DCB, m-DCB significantly (P less than 0.05) induced more micronuclei than o-DCB or p-DCB. No significant differences were found between the clastogenic activities of TCB isomers.