Blood Oxidative Stress Levels in Workers Exposed to Respirable Crystalline Silica in the West of Iran

Background: Occupational exposure to crystalline silica is still an important health problem, especially in developing countries. Exposure to silica may be associated with the induction of toxic oxidative stress. Objectives: This study was conducted to assess oxidative stress biomarkers in workers exposed to respirable crystalline silica (RCS) in Hamadan city, the west of Iran. Methods: This descriptive-analytical study was conducted on two groups of exposed workers selected from four industries and unexposed office workers in 2017. The analysis of RCS in air samples was done by NIOSH method No. 7602. Malondialdehyde (MDA), total antioxidant capacity (TAC), and catalase (CAT) activity were measured in serum samples. Results: In this study, 48 healthy workers exposed to silica and 47 unexposed workers as controls were selected. The mean MDA levels (26.91 ± 14.26 nmol/mL) and CAT activity (10.83 ± 5.06 U/mL) were higher in the exposed group than in the unexposed group (P < 0.001). However, no statistically significant difference was observed in the TAC levels between the groups and no correlation was observed between exposure to RCS and oxidative stress biomarker levels in exposed subjects. Conclusions: Although there was a significant difference in the oxidative stress levels between the groups, according to other results of our study, it is not possible to claim that oxidative stress biomarkers are appropriate biological indices for silica exposure monitoring in occupational settings. Therefore, we still require a comprehensive study of other aspects of this research field.