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Objective: To investigate the frequency of numerical aberrations for chromosomes 7 and 8 in the sperms of workers exposed to benzene series., Methods: Numerical aberrations in the sperms of workers were detected by two-color fluorescence in situ hybridization with biotin labeled chromosome 7 probe (D7Z1) and digoxingenin labeled chromosome 8 probe (D8Z1)., Results: The time-weight average air concentration (TWA) of benzene in the workshop was 42.29 mg/m(3), which was significantly higher than that of the national maximum allowable concentration [6 mg/m(3)]. The concentration of urinary trans,trans-muconic acid(ttMA) in the exposed group was also higher than that of the control group. In all, 155721 sperm nuclei from 15 workers in the exposed group and 123771 sperm nuclei from 12 individuals in the control group were examined. The results showed that the frequency of diploidy sperms and the frequencies of disomic sperm for chromosomes 7 and 8 in the exposed group (0.129%, 0.170%, 0.078%) were significantly higher than those of the control group (0.055%, 0.053%, 0.033%), respectively. The frequencies of nullisomic sperm for chromosomes 7 and 8 in the exposed group (0.165%, 0.088%) were also significantly increased, compared with those of the control group (0.056%, 0.029%). A statistically significant difference in the frequency of overall numerical chromosome aberrations was seen between the exposed group (0.745%) and the control group (0.289%)., Conclusion: The results suggested that higher concentration of benzene may induce higher frequencies of numerical aberrations in the sperms of workers exposed to benzene series.

To study the frequencies of numerical and structural aberrations for chromosome in sperm of benzene exposed workers, the multi-color FISH was used. Four DNA probes(one for chromosome 1 centromere and one for 1 p terminal, and two for chromosome 18 centromere) were hybridized with interphase sperms, and the frequencies of numerical aberrations for chromosome 1, 18 and structural aberrations of chromosome 1 were detected simultaneously. The time weighted average concentration (TWA) of benzene in workplace (42.29 mg/m3) was higher than that of our national maximum allowable concentration (6 mg/m3). The geometric concentration of urinary trans, trans-muconic acid(tt-MA) in exposed group was significantly higher than that of control group. A total of 144,282 sperm of 15 benzene-exposed workers and 135,937 sperm in 14 controls were scored. The frequency of hybridization efficiency was 99.85%. The mean frequencies of disomic sperms for chromosome 1 and 18 in exposed group(0.088% +/- 0.041%, and 0.087% +/- 0.049%, respectively) were statistically increased over that of the control group(0.045% +/- 0.024%, and 0.035% +/- 0.028%), and the mean frequencies of nullisomic sperms for chromosome 1 and 18(0.11% +/- 0.059%, 0.075% +/- 0.035%) in exposed group were statistically increased over that of control group too (0.048% +/- 0.018%; 0.045% +/- 0.024%). The frequencies of diploidy sperm were no difference in both exposed and control groups. The mean frequencies of terminal duplication and terminal deletion for chromosome 1 p(0.16% +/- 0.037%; 0.14% +/- 0.053%, respectively) were significantly increased over that of control group(0.082% +/- 0.023%; 0.069% +/- 0.028%, respectively). The mean frequencies of centromeric duplication and centromeric deletion for chromosome 1(0.10% +/- 0.035%; 0.10% +/- 0.041%, respectively) were significantly increased over that of control group(0.075% +/- 0.023%; 0.060% +/- 0.029%). Our experiments showed that exposed to benzene at higher concentration(42.29 mg/m3) may induce increases in frequencies not only of numerical aberrations for chromosome 1 and 18, but also of structural aberrations for chromosome 1 of sperms in exposed workers.