Chromosomal Aberrations in Lymphocytes of Individuals with Chronic Exposure to Gamma Radiation

Background-Apart from direct dose assessment of radiation exposure, analysis of chromosomal aberrations using the standard method has been widely used in monitoring the cytogenetic effects of long-term occupational radiation exposure. Chromosomal damage in human somatic cells may serve as an early indicator of hazard, thus enabling prevention of adverse effects.Methods-The frequency of chromosomal aberrations were evaluated in the peripheral blood lymphocytes obtained from 51 nuclear medicine technologists (NMT) who were exposed to chronic doses of gamma rays and 15 healthy controls. Lymphocytes were cultured in RPMI-1640 and metaphase plates were prepared using standard cytogenetic method. One hundred mitoses were analyzed for the presence of chromosomal aberrations for each sample. Radiation exposure was measured using film badge and thermoluminescent dosimeter (TLD).Results-The monthly dose equivalent received by the nuclear medicine technologists was between 0.03 to 2.80 mSv as measured by TLD and film badges. The frequencies of all types of aberrations (gaps, breaks and dicentrics) in exposed subjects were higher than those observed in the control group (p<0.0001). This study showed a linear dose-response relationship for total chromosomal deletions and dicentrics (p< 0.0001). Conclusion-The findings in this study are important, because radiation workers who have been exposed to doses well below accepted standards for exposure to radiation also show elevated levels of all types of chromosomal aberrations. Therefore, these results might imply that workers receiving very low doses of radiation during a long period of time could be considered as individuals at risk.