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.

Clastogenic effect of passive smoking on bone marrow polychromatic erythrocytes of NMRI mice.

The genotoxic effect of passive inhalation of sidestream cigarette smoke on bone marrow polychromatic erythrocytes was studied using male NMRI mice. The animals were placed in individual 145.2-dm3 glass chambers resembling a room provided with normal air flow. They were exposed to the sidestream smoke of a commercial brand of cigarettes smoked by a smoking machine under standard conditions. Increased formation of micronuclei within polychromatic erythrocytes (PCEs) of femoral bone marrow 30 h after passive smoking was regarded as being due to the clastogenic effect of the smoke. Passive inhalation of the diluted sidestream smoke of a single cigarette resulted in a significant increase (P less than 0.01) in the frequency of micronucleated PCEs. This clastogenic activity was found to be dose-dependent.