Kazakhstan is known as a country with a complex radioecological situation resulting from different sources such as a natural radiation background, extensive activities of the industrial system of the former Soviet Union and a well-known testing of nuclear power weapons occurred in the Semipalatinsk Test Site (STS) area. The present study focuses on the assessment of the background of dicentric chromosomes in Kazakhstan’s population, which is the starting point in the dose assessment of irradiated people, since the baseline level of spontaneous dicentrics can vary significantly in different populations. In this context, aiming to determine the background frequency of chromosome aberrations in the population of Kazakhstan, considering the heterogeneity of natural radiation background levels of its large territory, a selection of 40 control subjects living in four cities of North, South, West and East Kazakhstan was performed. The cytogenetic study on the selected groups showed fairly low background frequency values of chromosome aberrations (0.84 ± 0.83 per 1000 cells), comparable with other data in the literature on general populations, reporting background frequency values between 0.54 and 2.99 per 1000 cells. The obtained results should be taken into account when constructing the dose–effect calibration curve used in cytogenetic biodosimetry, as a “zero” dose point, which will reduce the uncertainty in quantifying the individual absorbed dose in emergency radiological situations.

В настоящее время повышенные концентрации трития в окружающей среде, связанные с производством, обращением и утилизацией радиоактивной формы водо-рода на ядерных объектах, вызывают большую озабоченность общественности, так как не существует эффективных способов для улавливания радионуклида. Тритий со сбросами и выбросами предприятий ядерного топливного цикла (ЯТЦ) поступает в водные и наземные экосисте-

The paper provides results of quantitative assessment of 3H incorporation by Helianthus Annuus in case of intake through the roots in vitro. It was found, that in case of chronic 3H intake through the roots, R factor value for Helianthus Annuus during vegetation period ranges between 0.11 and 0.27 with the average of 0.21. The rate of generation of triturated organic matter ranges between 0.08 and 0.044% per hour, with the maximum value reached at the leaf formation stage. Translocation index for Helianthus Annuus in case of intake of 3H through the roots is 65%, that is almost 2.5 times higher than for aerial uptake of the radionuclide. Values of 3H distribution among the organs of Helianthus Annuus when continuously received through the roots decreases for tissue free water tritium (TFWT) in the range “roots > flowers > stalks > leafs”, while for organically bound tritium (OBT) these decrease in the range “flowers > stalks > leafs > roots”. When Helianthus Annuus absorbs 3H through the roots TFWT activity values correlate well with activity of the radionuclide in water, absorbed by the roots (г = 0.89). Regularities found in distribution of 3H among the organs of Helianthus Annuus and R values are of practical importance for biomonitoring of contamination of environmental objects with tritium.