The aim of the study is to assess the health status of Kozloduy Nuclear Power Plant personnel in association with their occupational exposure to low doses of ionising radiation (IR) as well as with other factors of their working environment and to determine the probability of the occupational exposure to be a reason for the diagnosed malignant diseases (Probability of Causation – PC). More than 1000 occupationally exposed workers and nonexposed administrative staff have been studied during 1993–2008. No statistically significant variation in the average cumulative dose was found between the healthy people and the persons with at least one disorder. The highest rate of morbidity was registered in persons with doses up to 1 mSv. The analysis of parameters of peripheral blood showed that at occupational lowdose exposure the haemopoietic system completely preserves the tri-linear cell proliferation capacity of the bone marrow. The analysis of results of PC demonstrated that this is spontaneously arising malignant diseases, regardless of condition of work.
Keywords: NPP workers, low-dose radiation, health effects, medical surveillance, cancer, probability of causation