Biological indicators of occupational radiation exposure

摘要

The report presents results on finding appropriate biomarkers applicable in molecularepidemiological surveys of occupationally exposed individuals and/or population to study low dose effects.Blood samples were collected from the “strict regimen” area personnel (exposed) and the administrative staff(controls) of NPP-Kozlodui. Two levels of evaluation were used: ~1molecular - spontaneous and induced DNArepair by UDS, protein synthesis evaluated radio-metrically, DNA damage by SCGE – all of them in white bloodcells, concentration of malonedialdehyde in blood serum; and ~2cellular – the Ly-subsets by flow cytometry,using a FacScan analyzer and immunofluorescent stained mouse monoclonal antibodies. A significant decreaseof potentially lethal damage was found in persons with “mean annual dose” lower or equal to 5 mSv/a. Thehighest repair capacity and protein synthesis after a challenging dose of 2,0 Gy gamma rays as well as asignificant decrease in the level of oxidative stress were evaluated for persons from the same group. At dosesbelow 200 mSv statistically different decrease of the index of СD3+4+, CD4+25+, СD4+62L+ lymphocytepopulations and СD4/СD8 cell ratio was established, and increased levels of NK cells, CD57+8+, CD8+28+and CD8+38 were recorded. The present investigation showed that annual doses lower than twice the naturalradiation background exert positive effects on DNA damage and repair, increase cellular resistance and decreaseoxidative stress. It is possible that the positive correlation between the dose and the cells with phenotypeCD4+25+ and CD57+8+, as well as the negative one with CD4+62L+, CD8+28+ and CD8+38+, could reflectadaptive processes and compensatory activated immune system due to low dose irradiation. Furtherinvestigations allowing analysis of the molecular endpoints, increase the sensitivity of studies and help to searcheffects of low radiation exposures, are needed.