Рентгенология & Радиология, 2015, LIV 222-226

Cellular repair capacity of occupationally exposed to low-dose radiation workers from the nuclear industry
  1. Stankova, V. Nikolov, K. Ivanova, R. Georgievа, R. Boteva
Abstract.

Cytotoxic effects of ionizing radiation (IR) are attributed to radiation-induced damage in DNA molecules mainly. Therefore, levels of persistent DNA damage and individual repair capacity are accepted biomarkers in health monitoring studies including individuals, occupationally exposed to low-dose gamma IR. The present study included two groups of occupationally exposed to radiation workers with accumulated doses below and above 200 mSv, respectively, and a non-exposed control group. All participants in the study were employees at the “Kozloduy” Nuclear Power Plant (NPP), Bulgaria. The experimental groups were compared considering the levels of DNA damage and the capacity of the cellular machinery to repair damaged DNA, analyzed by the Comet test (CT). CT is electrophoretic method for analysis of DNA fragmentation at a single cell level. The cellular repair capacity was studied after additional in vitro exposure of lymphocytes of each subject to a challenge dose of 2 Gy of gamma radiation accounted for the residual DNA damage 2 h post-irradiation. Positive association of persisting DNA damage and cellular repair capacity of lymphocytes with age of the subjects included in the non-exposed control group and the exposed group with higher than 200 mSv cumulative doses was found. For the exposed group encompassing workers with lower than 200 mSv cumulative doses, the opposite tendency, namely decrease of the level of DNA fragmentation with increasing the age of the subjects was observed. This finding is indicative of adaptive response induced by the chronic exposure of theworkers to low doses of IR which may increase the individual radioresistance.

Key words: EPIDEMIOLOGY. RADIATION PROTECTION. CELLULAR REPAIR