Chronic Hematologic Toxicity with Inhalation Exposure to Low Concentration of Benzene in BALB/C Mice

To explore the chronic hematologic toxicity in BALB/C mice exposed to low concentration of benzene which is equal to concentration of Chinese occupational hygiene standard, the benzene (20mg/m
³
) was applied to BALB/C mice by inhalation exposure, once per day, for 3 month and the mice were raised for another 90 days after exposure. During the experimental period, micronucleus frequency in peripheral blood reticulocyts, comet assay in peripheral blood leucocytes, parameters of peripheral blood, and bone marrow examination were detected. It was shown that the micronucleus frequency and DNA damage ratios were higher in benzene exposure group. The damage in benzene group showed more serious till another 90 days after treatment. The haematological examination of blood in benzene exposure group was significantly different from the control group. The bone marrow examination showed the myelodysplastic syndrome (MDS) happened in benzene exposure group. It suggested the hemopoietic function could be influenced and malignant cloning disease in hemopoietic system could be induced by long-term inhalation exposure to low concentration of benzene.