Tehran University of Medical Sciences Journal of Air Pollution and Health 2476-3071 9 2 2024 06 24 225 234 Hoda Arabzadeh Department of Epidemiology, Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran Ali Poormohammadi Center of Excellence for Occupational Health, Occupational Health and Safety Research Center, School of Public Health, Hamadan University of Medical Sciences Hamadan, Iran Salman Khazaei Department of Epidemiology, Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran Marzieh Fattahi Darghlou Department of Epidemiology, Research Center for Health Sciences, Hamadan University of Medical Sciences, Hamadan, Iran 2023 10 26 2024 06 05 In this present study, the association between occupational exposure to Respirable Crystalline Silica (RCS) and serum level of Clara Cell Protein (CC16) was investigated in the form of a systematic review and meta-analysis. Various databases including PubMed, Scopus, and Web of Sciences were searched until August 2022 based on Medical subject headings (MeSH) such as "CC10 protein, human" OR "Clara-cell specific 10-kD protein "OR "Clara cell phospholipid-binding protein human" AND Silicosis. Standardized Mean Difference (SMD) was used to compare the mean difference in CC16 serum levels between the silicotic and non-silicotic groups. During the initial database search until August 2022, 18 articles were found. By excluding duplicates and final screening in terms of compliance with the title and objectives, eight articles were included in our analysis. The overall effect estimate demonstrated that silicosis patients had lower serum level of CC16 (SMD:-3.58; 95% CI, from -5.14 to-2.3; I2 = 94.4% P-value<0.001) than that of the control group. Moreover, silicosis patients and exposed individuals had lower serum level of CC16 (SMD:-3.32; 95% CI, from -4.19 to -2.45; I2 = 88.6% P-value<0.001) compared to the control group. The silica exposure had a lower CC16 level (SMD:-1.92; 95% CI, from -4.22 to 0.39; I2= 97.5% P-value<0.001) than the non-silicosis groups. The results demonstrated that occupational exposure to RCS is associated with the reduction of serum CC16 level. Therefore, the reduced serum level  of CC16 protein can be used to monitor the maximum exposure level of workers to RCS in related workplaces. https://japh.tums.ac.ir/index.php/japh/article/view/612 https://japh.tums.ac.ir/index.php/japh/article/download/612/400