[Cytogenetic examination of nuclear specialists exposed to chronic beta-radiation of tritium].

For the first time the cytogenetic examination of the group of nuclear specialists (79 persons) chronically exposed to tritium beta-radiation for a long period was carried out. The frequencies of unstable (conventional method) and stable (FISH-method) chromosome aberrations have been analyzed. 50 years after the beginning of working under the conditions of the increased radiation level the differences (in comparison with control values) were revealed for all cytogenetic parameters. The frequency of the radiation-specific markers (dicentrics and centric rings) exceeds more than 2-fold the control level. A significant but poor correlation between the frequency of unstable aberrations and the total absorbed dose (during the whole working period) was revealed. A retrospective estimation of irradiation doses for 14 nuclear workers was made by the frequency of stable chromosome aberrations. The obtained dose values ranged from 110 to 1250 mSv.

[Cytogenetic effect of small doses of tritium beta irradiation]. / Tsitogeneticheskii éffekt malykh doz beta-izlucheniia tritiia.

The effect of tritium beta-radiation within the dose range of 0.5 x 10(-3) = 0.6 Gy on human blood lymphocytes in vitro was investigated. Dose-effect correlation was determined by the frequency of aberrant cells and the sum of chromosome aberrations per 100 cells. As compared to a rated curve corresponding to a linear-quadratic model y = a + bD + cD2, experimental curves (showing correlation between cytogenetic indices and a dose) are of abnormal nature with a plateau in a dose range less than 7.5 x 10(-2) Gy. A big confidence interval of cytogenetic effect indices in a dose range less than 7.5 x 10(-2) Gy was shown to be determined by the number of analyzed metaphases. The proof of significance of a plateau on a dose-effect curve in regions of small doses (e.g. with a confidence interval of +/- 24%) necessitated analysis of no less than 10,000 metaphases per dose.