Renal and hepatic injury markers trajectories and respiratory symptoms in iron ore processing plant workers

Abstract Mining is a high-risk occupation, with mineral dust exposure leading to various occupational diseases. This study aimed to assess respiratory symptoms and longitudinal changes in renal and hepatic injury markers among workers occupationally exposed to iron dust and crystalline silica in an iron ore processing plant. The study population included three job groups: cleaning, engineering/technical, and administrative staff. Iron and crystalline silica dust samples were collected using cyclone samplers with MCE and PVC filters, analyzed by atomic absorption and spectrophotometric techniques, respectively. Respiratory symptoms (wheezing, shortness of breath, cough, phlegm) were assessed via the Persian version of the American Lung Association Respiratory Questionnaire. Periodic medical examination records were reviewed to evaluate renal (urea, creatinine) and hepatic (SGOT, Serum Glutamic-Oxaloacetic Transaminase; SGPT, Serum Glutamic-Pyruvic Transaminase) injury markers. Mean exposure concentrations of iron and crystalline silica dust were highest among cleaning staff, followed by technical staff, and lowest among administrative staff. Compared with administrative staff, the odds of phlegm and shortness of breath were higher among cleaning staff (OR = 50.56, 95% CI: 8.86–288.59; OR = 9.46, 95% CI: 1.71–52.39, respectively) and technical staff (OR = 9.19, 95% CI: 4.00–21.11; OR = 11.05, 95% CI: 4.57–26.69, respectively). Statistically significant differences were observed in the trends of renal and hepatic injury biomarkers across job groups. The annual increase rate in creatinine, SGOT, and SGPT levels was highest in cleaning staff, and lowest in administrative staff. A Linear Mixed Regression model revealed that work history, job group, education level, employment type, and concentrations of iron and crystalline silica dust significantly influenced biochemical markers trends. These findings can be useful in selecting and implementing control measures as best as possible.