| Abstract [eng] |
Justas Morkūnas Occupational radiation exposure and cytogenetic monitoring of Ignalina Nuclear Power Plant workers SUMMARY The Ignalina Nuclear Power Plant workers (INPP) represent the largest group of workers occupationally exposed to low-level doses of ionizing radiation in Lithuania. Though individual doses of the INPP workers for many years have been declining and are retained within officially accepted limits, many reports demonstrate that low-level occupational exposure to ionizing radiation can significantly increase chromosome aberration levels in blood lymphocytes. Moreover, chromosome aberrations are believed to be a possible biomarker reflecting chromosome damage in target tissues which in turn is linked to cancer development. Therefore many studies have been dedicated to investigate the cytogenetic effects of low-level radiation in blood lymphocytes, especially trying to establish dose-effect relationship and predict possible cancer risks. The objective of the current study was to analyze chromosome aberration levels in lymphocytes of the INPP workers subjected to relatively high individual doses of occupational exposure (mean accumulated doses 280.2±44.9 mSv), taking into consideration different types of ionizing radiation. A total of 21 blood samples from INPP workers and 17 control samples were analyzed. Cytogenetic analysis revealed significantly increased CA levels in the whole group of INPP workers (3.26±0.34 CA/100 cells) and a subgroup of workers additionally exposed to internal radiation (3.61±0.45 CA/100 cells), when compared to controls (2.18±0.17, p <0.05). No significant increase in CA frequency was observed for a subgroup exposed to external γ-rays only. When taking into account the yield of chromosome-type aberrations, acentric fragments and dicentrinc chromosomes all groups significantly differed from the control group (p <0.05). Significant increase in dicentric + ring chromosomes (0.70±0.14/100 cells) was observed in a subgroup of workers additionally exposed to internal radiation as compared to workers with external irradiation. A comparison of two repeated samples (within period of 3 years) from 7 selected workers demonstrated a significant decrease in chromatid-type aberrations. The analysis of variance disclosed a significant input of occupational exposure to the yields of chromosome type aberrations and acentric fragments in the INPP workers. A significant influence of internal exposure was confirmed for dicentric + ring chromosome levels. No correlation between the accumulated doses and aberration yields was determined, neither was the influence of such factors as smoking, age and working time confirmed. |
