Methodical approaches to estimate health risk under prolonged and chronic long term exposure to ionizing radiation

Introduction The many year investigation summing results of different groups of people employed (or lived) in different conditions of long term chronic repeated exposure to ionizing radiation sources are analyzed, which investigations were participated by author. The clinical data interpretation was comprised with exposure levels of external and internal exposure sources (A.K. Guskova, G.D. Baisogolov, N.D. Okladnikova, A.V. Akleev, M.M. Kosenko, I.I. Kiroushkin et al) as well as health effects in different groups of different dose levels and dose rates. Early effects are revealed including these of subclinical shifts of the status of most radiosensitive and critical body systems to manifested forms of chronic radiation sickness (CRD) and its different variants (classificated by G.D. Baisogolov, A.K. Guskova, 1969). Materials of original studies of different occupational groups (atomic industry personnel, personnel of research reactors and industrial reactors and cyclotrons, medical x-ray technicians, etc.) were compared to literature references on radium project and health data in personnel of atomic power plants and other facilities of different countries. Basing upon these comparisons the approximate dose thresholds were determined to induce clinical manifestations in hemopoiesis and adaptive system reactions (nervous system, cardiovascular system, endocrine system) specific to CRD. The termination of irradiation or sharp decrease of its rate to 5 cSv/year have resulted to regress of the indicated manifestations (or to its prophylaxis in case of exposure below the dose threshold), which was evaluated to be the major therapeutic prophylactic measure of the system of human protection against chronic exposure. Some data are also provided (G.D. Baisogolov, V.N. Doshenko, N.A. Koshurnikova, V.F. Khokhriakov, N.D. Okladnikova) on late effects of chronic exposure (leukemias, solid cancers) and outcomes of chronic radiation sickness syndromes (A.K. Guskova, G.D. Baisogolov, V.N. Doshenko, T.V. Azizova, N.D. Okladnikova) for the observations within terms of up to 40 years.