Objective Medical personnel using radiation for diagnosis and therapeutic purposes are potentially at risk of cancer development. In this study, the effect of ionising radiation (IR) exposure was evaluated as DNA damage response (DDR) in the circulating cells of occupationally exposed subjects.
Methods The study population consisted of IR-exposed workers included both in group B (effective dose ranging between 0.04 and 6 mSv/year) and group A (probable effective dose exceeding 6 mSv/year), and the control group consisted of healthy individuals who had never been occupationally exposed to IR or other known carcinogenic agents. DNA damage (single-strand breaks, oxidised purine and pyrimidine bases) and DNA repair (t1/2, half time to repair DNA damage, amount of repaired DNA and DNA repair activity) were measured in lymphocytes using the comet assay. To evaluate the influence of IR doses and genetic predisposition to cancer, the enrolled population was stratified according to IR exposure level and family history of cancer.
Results Increased DNA repair activity was found in IR-exposed group, and only subjects highly exposed to IR doses accumulated DNA damage in their circulating cells, thus supporting the hypothesis of ‘radiation hormesis’. A significant increase in DNA damage accumulation and a reduced 8-oxoguanine glycosylase 1-dependent DNA repair activity were found in IR-exposed subjects with cancer cases across their family.
Conclusion Our results indicate that chronic exposure to a low dose of IR in occupational settings induces DDR in exposed subjects and may be mutagenic in workers with family history of cancer, suggesting that periodic surveillance might be advisable, along with exposure monitoring.
- ionizing radiation
- occupational exposure
- Dna damage response
- ogg1-dependent Dna repair activity
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Contributors Each author has contributed to the submitted work as follows: SG designed the study and performed the analysis. MB, GI, MA and FM coordinated participant recruitment and managed the data. GI and MA managed the exposure assessment and developed the job-specific questionnaires. MT drafted the manuscript and participated in the data collection and statistical analyses. LS and MV reviewed the literature and revised the manuscript. All authors participated in the analysis plan. All coauthors collaborated interactively, contributed to the interpretation of the results and discussion, and read and approved the final manuscript. Each author believes that the manuscript represents honest work.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Obtained.
Ethics approval The study followed the guidelines of the Declaration of Helsinki regarding medical research involving human subjects and was approved by the Ethical Committee of the University Hospital of Marche (Ospedali Riuniti di Ancona), Italy.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional unpublished data are available.