Abstract: OBJECTIVE: To explore the subacute toxicity and genotoxicity of benzene and formaldehyde co-exposure in BALB/c mice. METHODS: BALB/c mice were exposed to benzene (50 mg/kg, dissolved in corn oil) , formaldehyde (2 mg/kg,dissolved in saline) and Solvent control group(corn oil and formaldehyde). The mice of each group were treated with test materials by intraperitoneal injection, once per day, for 30 d. The mice were bred for another 30 d after treatment. During the experiment period, growth of the mice was observed. Meanwhile, following indices were evaluated: parameters of peripheral blood, micronucleus frequency in leucocytes and comet assay in leucocytes. RESULTS: The body weight decreased in benzene-formaldehyde co-exposure group and decreased continually after exposure without significant difference compared with control groups. The RBC was decreased significantly in benzene and co-exposure group(P<0.05), but the parameters of peripheral blood recovered 30 d after exposure. Benzene and formaldehyde exerted a synergistic effect on the significant increase of micronucleus frequency and DNA damage ratios(P<0.05). The effects lasted till 30 d and still higher than control groups after co-exposure. CONCLUSION: Subacute toxicity caused by co-exposure of benzene and formaldehyde in mice led to synergistic and persistant genotoxicity.

Key words: benzene, formaldehyde, BALB/c mice, subacute toxicity, genotoxicity