Consecutive results of blood cell count and retrospective biodosimetry: useful tools of health protection regulation for radiation workers

BACKGROUND Industrial radiography is known to be one of the most vulnerable lines of work among the range of different radiation work. According to the relevant law in Korea, every worker registered in this work should check their blood cell counts every year in addition to their thermoluminescent dosimeter (TLD) doses. Since the law was enacted, however, few follow-up studies have been carried out based on the obtained results. OBJECTIVES To ascertain the clinical usefulness of complete blood cell count (CBC) results and suggest a proper protocol of health protection for radiation workers. METHODS After reviewing all the consecutive results of CBC and TLD doses from radiation workers registered nationwide, we selected two groups of high-risk radiation workers, CBC-high risk (CBC-HR) and TLD-high risk (TLD-HR) groups. A control group of unexposed healthy adults was also included. We compared the absorbed doses calculated by cytogenetic biodosimetry among those three groups, and examined possible confounding factors for each group. RESULTS Both groups of high-risk radiation workers, CBC-HR and TLD-HR, showed higher chromosome aberrations than the control group. In the control group, previous medical history of a CT scan increased the frequency of chromosome aberrations. In contrast, the frequency of chromosome aberrations in the high-risk radiation workers was affected not by the previous CT history but only by the duration of their work. CONCLUSIONS We ascertain that reviewing consecutive results of blood cell counts and cytogenetic biodosimetry are useful complementary tools to TLD doses for health protection regulation. Several confounding factors including work duration and previous medical history need to be considered for the interpretation of biodosimetry results.