Detection of Mitochondrial DNA Deletion in Medical Workers Occupationally Exposed to Ionizing Radiation in Tripoli, Libya

Abstract

Occupational exposure to low-dose ionizing radiation poses chronic health risks to radiology personnel. While traditional monitoring captures recent damage, modern molecular epidemiology focuses on mitochondrial DNA (mtDNA) alterations. Due to limited repair mechanisms, the mitochondrial genome is highly sensitive to radiation, making mtDNA alterations valuable biomarkers for cumulative genetic injury. This study aimed to assess the potential induction of the mtDNA4977 deletion and variations in mtDNA-CN in the blood of staff members working in radiology departments across three medical facilities in Tripoli, Libya. A total of 72 participants were recruited from Metiga Military Hospital, Alkhadra General Hospital, and the National Center for Disease Control–Libya between July and October 2024. The study population included 50 radiation-exposed workers (Group A) and 22 non-exposed individuals (Group B). Data were obtained using a structured questionnaire and peripheral blood sampling. Quantitative real-time PCR was applied to evaluate mtDNA-CN and detect the mtDNA4977 deletion. ΔCt values for mtDNA4977 were significantly lower in the radiation-exposed group than in controls, indicating higher levels of mitochondrial DNA deletions among exposed workers. mtDNA-CN was also significantly reduced in the exposed group, suggesting possible radiation-induced mitochondrial depletion. Multivariable linear regression models further confirmed that occupational radiation exposure remained an independent and highly significant predictor of both mitochondrial alterations, even after adjusting for age and smoking status. These findings demonstrate a clear association between occupational exposure to ionizing radiation and alterations in mtDNA. Increased mtDNA4977 deletions and reduced mtDNA-CN among exposed workers highlight their potential as biomarkers of chronic radiation exposure. Consequently, these results underscore the critical importance of continuous biological monitoring and reinforcement of protective measures for radiology staff.