About assessment of potential risk in the nuclear industry using an example of the Leningrad NPP

As of today it does not seem possible to assess objectively the causality between cancer diseases and professional exposure using clinical evidence only. On the other hand, the medical-dosimetric registries can do little to reveal statistically significant effects in the low dose range and do not provide unambiguous recommendations as to quantifying occurrence of malignant neoplasms in case of protracted exposure. The remaining option is to use the accumulated experience of large-scale epidemiological studies and existing recommendations for probabilistic assessment of possible occurrence of malignant neoplasms associated with professional activity for a given individual with allowance for his personal characteristics. In the paper the personnel of the Leningrad NPP under individual dosimetric monitoring is grouped with respect to potential risk. The projection methodology recommended by UNSCEAR-94 is used. the source information is personalized data allowing for sex, age and year-by-year dynamics of dose accumulation. A total of 5086 males are considered, their average accumulated dose being 74 mSv. Since the large-.scale epidemiological studies have not revealed radiation induction of cancer diseases in the low dose range, in the first stage the cohort of the Leningrad NPP workers with accumulated radiation doses more than 200 mSv was selected. for 289 persons who received accumulated doses more than 200 mSv (5.6% of the whole staff) the following distribution is derived: 138 workers had the attributive risk ranging from 5% to 10% 7 workers-from 10% to 15%. the derived distribution can be used as a basis for administrative decision making. The proposed methodology for assessing individual potential risk of malignant neoplasms associated with professional activity can be used in the practice of NPP radiation safety services. (Author) 8 refs