Abstract: ObjectiveTo study the genetic toxicity in human bronchial epithelial cells (BEAS-2B) induced by cigarette smoke extraction (CSE) and protective effect of tea polyphenols (TPs) on the toxicity. MethodsThe BEAS-2B cells were exposed to high,moderate,and low concentration of CSE in culture medium and a tea polyphenols protection group and a control group were set up.Comet assay and H2AX phosphorylation were adopted to detect DNA damage and micronucleus assay was used to estimate chromosomal damage and hypoxanthine phosphoribosyl (HPRT) gene mutation. ResultsCompared to those of the control group,the number of comet cells (130.5 ± 1.6),tail length (134.33±3.56 μm),the tail area (7 798.43 ± 43.45 μm²) for BEAS-2B cells of high dose CSE exposure group increased significantly (P<0.05 for all) in a dose-effect manner.The number of cells with micronucleus in 1 000 BEAS-2B cells exposed to low,moderate,and high CSE were 22.4±3.2, 38.6±1.8,and 79.6±2.4,respectively,and significantly higher than that of the control group (6.2±1.5) (P<0.05 for all).The CSE significantly inbihit the increases of HPRT gene mutation rate,DNA chain break and number of cells with micronucleus induced by CSE exposure in BEAS-2B cells. ConclusionCSE has genotoxicity and tea polyphenols could inhibit the genetic toxicity of CSE.