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

Abstract

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.

Evaluation of oxidative stress and biochemical biomarkers, and psychological parameters in cement plant workers

“…In the present study, the concentrations of SOD and CAT in the exposed group were significantly higher than the non-exposed group. Similar studies have showed that the levels of SOD and CAT were higher in workers exposed to noise (77–99 dB) (Hosseinabadi et al, 2019); and among workers exposed to silica (Farokhzad et al, 2019; Özgüner et al, 1999). Increased levels of CAT and SOD represent an increase in oxidative stress; in fact, such enzymatic antioxidants are activated in response to the overproduction of free radicals.…”

“…This decrease may be because of eliminating the free radicals that are generated by oxidizing agents (cement dust, silica, and noise) in the exposed group (Balbi et al, 2018; Rani and Mythili, 2014). However, in Malekirad’s study at a cement plant (Malekirad et al, 2019), and another similar study on workers exposed to silica, TAC levels were not significantly different in the exposed and non-exposed groups (Farokhzad et al, 2019). The reason for the insignificant difference in the level of TAC among exposed and non-exposed groups in our study and other studies could be due to the indirect effect of oxidative agents on the level of TAC.…”

Evaluation of Oxidative Stress and Biochemical Biomarkers, and Psychological Parameters in Cement Plant Workers

“…In the present study, the amounts of SOD and CAT in the exposed group were signi cantly higher than the non-exposed group. Similar studies have showed that SOD and CAT were higher in workers exposed to noise (77-99 dB) [49]; and among workers exposed to silica [34,47]. [50].…”

“…The serum level of AST and ALT enzymes are used to evaluate liver function. The liver is the most important organ for cleansing the body from various toxins.AST accumulates in damaged organs including the liver, skeletal muscles, heart and kidney [52,53].Similar studies done in cement factories have shown an increase in AST levels in groups exposed to cement compared to the non-exposed groups as well [33,40,47].…”

“…This slight decrease may be because of eliminating the free radicals that are generated by oxidating agents (cement dust, silica, and noise) in the exposed group [45,46]. However, in Malekirad's study at a cement plant [2],and another similar study on workers exposed to silica, TAC levels were not signi cantly different in the exposed and unexposed groups [47]. The reason for the insigni cant difference in the level of TAC among exposed and unexposed groups in our study and other studies could be due to the indirect effect of oxidative agents on TAC.…”