Health Risk Assessment of Occupational Exposure to Chemical Materials in a Combined-Cycle Power Plant

Background: This study aimed to evaluate the occupational exposure of workers at a combined-cycle power plant located in the southwestern region of Iran. The assessment focuses on the inhalation exposure route to workplace emissions. Methods: The primary locations for potential pollutant emissions were identified in close proximity to the areas where chemicals were introduced and utilized within the production process. Sulfuric acid, sodium hydroxide, ammonia, oil mist, toluene, hydrogen sulfide, hydrazine, and tetrachloromethane were measured and analyzed using the NIOSH standard. Dose-response assessment was estimated using inhalation unit risk (IUR) for cancer risks and reference concentration (RFC) and reference exposure levels (REL) for non-cancer risks. Risk assessment was performed based on the Environmental Health Hazard Assessment guideline. Results: The results showed that ammonia and toluene had the highest and lowest concentration of pollutants emitted in workplace, respectively. The inhalation of ammonia and sulfuric acid and their daily absorption were at high risk level (HQ>1). Other noncancerous compounds had HQ<1. While the hazard index (HI) for total non-cancer risks was 5.34E+01 (HI>1), it was likely to have non-cancerous risks. For carcinogenic risks, they were calculated to be 9.58E-03 and 5.47E-04 for hydrazine and tetrachloromethane, respectively. The total carcinogenic risk of the emissions was calculated at 1.01E-02, which was in the significant range (more than 10-4) (i.e. in the range of hazardous cancer effects). Conclusion: This study confirmed the presence of non-carcinogenic risks, while the quantity of cancer risks fell within the Significant range, indicating a potential for carcinogenic risks.