Assessment of genotoxic effects related to chronic low level exposure to ionizing radiation using biomarkers for DNA damage and repair

Abstract

The first objective of our study was to analyse whether biomarkers for genotoxic effects (DNA breaks and alkali-labile sites and micronucleus and non-disjunction frequencies) could be fully validated for biomonitoring workers chronically exposed to ionizing radiation (IR). Blood samples of controls and individuals chronically exposed to IR were analysed. The interindividual variation was reduced when the comet data were adjusted for interexperimental variation, but remained statistically significant. No differences were found between groups, either for smoking or for exposure status. The second objective was to determine whether the Comet assay can be used to evaluate global repair phenotype as a susceptibility biomarker for IR-induced DNA damage in nuclear workers. A pilot study was performed and blood from workers exposed or not to radiation was submitted to a challenging dose of gamma-rays. The repair kinetics of each individual donor were analysed by Comet assay at different time points and compared with the frequencies of biomarkers of genotoxic effects. There was a statistically significant interaction between biomarkers assessing the same damage (micronucleus and Comet assays). Multivariate analysis showed that micronucleus frequencies were positively influenced by age and the percentage of residual tail length was negatively influenced by the interaction between smoking and exposure status. The general conclusions from our study are: (i) a positive correlation exists between mechanistically related biomarkers; (ii) multivariate regression analysis confirmed that the interaction between smoking and exposure to IR negatively and statistically significantly influenced residual tail length; (iii) use of the Comet assay for the estimation of global repair phenotype with respect to IR is recommended because it is simple, fast and differences in in vitro repair capacity can be detected.

Polymorphisms in DNA repair genes: link with biomarkers of the CBMN cytome assay in hospital workers chronically exposed to low doses of ionising radiation / Polimorfizmi u genima za popravak DNA: poveznica s biomarkerima mikronukleus-testa u medicinskih radnika kronično izloženih niskim dozama ionizirajućeg zračenja

“…Achieving a complete understanding of this interaction may be of great importance for implementing radiation protection and radiotherapy programmes (37,38). In view of this, concomitant analysis of DNA damage and interindividual differences in DNA repair genes, due to the presence of polymorphisms, may represent a valuable multi-biomarker approach (39).…”

Impacts of Terrestrial Ionizing Radiation on the Hematopoietic System

“…Radon-222 gas, even at lower doses, can enter the body through pulmonary alveoli; as a result, it can irradiate different organs, especially in the people who live near elevated levels of natural background radiation [49,50]. DNA damage and chromosomal aberrations were found in the peripheral blood lymphocytes and leukocytes of those workers who were exposed to uranium compounds emerging from lowdose radiation [51][52][53][54][55][56]. Also, mortalities from kidney, bladder, and esophagus cancers were likely to increase, but chronic renal diseases were observed to be significantly higher [57][58][59].…”

The Biliprotein C-Phycocyanin Modulates the DNA Damage Response in Lymphocytes from Nuclear Power Plant Workers

“…The amount of persisting DSBs in cells was determined by the comet assay (CA), a quick, simple and reliable method for analyzing DNA damage and repair that requires a small number of cells and can be performed on both freshly isolated and cryopreserved cells (Decordier et al, 2010). Due to its sensitivity, the method is preferred in human epidemiological studies related to biomonitoring (Möller et al, 2000;Touil et al, 2002). Additionally, the CA is able to provide information on different types of DNA damage/repair and detect cellular damage in a wide dose range of exposures from 0.05 to 10 Gy (Kalthur et al, 2008;Mohseni-Meybodi et al, 2009;Palyvoda et al, 2003).…”