Tehran University of Medical Sciences Journal of Air Pollution and Health 2476-3071 7 4 2022 12 18 341 346 Ali Poormohammadi 1. Center of Excellence for Occupational Health, Occupational Health and Safety Research Center, School of Public Health, Hamadan University of Medical Sciences Hamadan, Iran Erfan Ayubi Social Determinants of Health Research Center, Hamadan University of Medical Sciences, Hamadan, Iran Nastaran Barati Medicinal Plants and Natural Products Research Center, Hamadan University of Medical Sciences, Hamadan, Iran Seyedmousa Motavallihaghi 4. Department of Parasitology and Mycology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran Effat Sadat Mir Moeini Center of Excellence for Occupational Health, Occupational Health and Safety Research Center, School of Public Health, Hamadan University of Medical Sciences Hamadan, Iran Fereshteh Mehri Center of Excellence for Occupational Health, Occupational Health and Safety Research Center, School of Public Health, Hamadan University of Medical Sciences Hamadan, Iran 2022 08 03 2022 11 01 Introduction: Due to the obvious adverse effects of exposure to free crystalline silica and the high exposure level in silica-related occupations, the present study aimed at the investigation of renal symptoms in cement factory workers. Materials and methods: For this reason, 128 workers who were working cement factory with a determined occupational exposure to crystalline-free silica were selected as the case group, and 143 workers who were working in the Hamedan Province Rural Water and Wastewater company without being exposed to crystalline free silica were selected as controls. Various kidney-related parameters were evaluated and compared between the selected case and control groups. Results: The results of urine analysis between cases and control showed that there was a statistical difference between the cases and controls regarding Red Blood Cell (RBC), epithelial count, and bacteria (p<0.05). Moreover, the percentage of amorphous urate crystals of the exposed workers (cases) and control were 80.7% and 38.3%, respectively (p<0.001). The results of adjusted results showed that the odd presence of amorphous urate crystals among cases was 7.65 times of the control group (p<0.001). Conclusion: Our findings clearly showed that the level of urinary levels of amorphous urate crystals in silica-exposed individuals is higher than that of non-exposed individuals. Therefore, the presence of urinary amorphous urate crystals in exposed workers may be used as a cheap, non-invasive, and efficient method and urine biological maker for detecting silica exposure in silica-related industries. https://japh.tums.ac.ir/index.php/japh/article/view/425 https://japh.tums.ac.ir/index.php/japh/article/download/425/326