Abstract

Occupational exposure to silica dust can cause various complications. Genetic side effects are possible complications raised about exposure to silica. The aim of this study was to assess the rate of DNA damage using Comet assay in lymphocytes of mice following exposure to silica dust. In total, 72 male BALB/c mice were selected and divided into five groups of 12 animals with respiratory exposure to pure silica dust at concentrations of 1.3, 3, 8, 12 and 17 mg/m3, as well as a non-exposed control group. The mice were exposed for 8 hours a day, 6 days a week for 1, 2, 3 and 4 months. Then, blood samples were taken from the mice to determine the level of lymphocyte DNA damage using Comet assay under fluorescence microscope and comet score software. The obtained results were analyzed using SPSS version 19 at a significance level of less than 0.05. The highest level of Tail length was found in the fourth month and in the Group 1. The results of DNA damage showed no significant difference among any of the groups in the first month compared with the control group (p> 0.05). After the second month, there was a significant difference only in the Groups 1 and 2, which were exposed to high concentrations of silica (p <0.05). In the third and fourth months after exposure, DNA damage revealed significant differences in all groups compared to control (p <0.05). More than two months exposure to silica dust even at low concentrations can cause significant DNA damage in lymphocytes of BALB/c mice compared to the control.