THYROID GLAND DISEASES AND FACTORS, WHICH IMPACT ON ITS POPULATION PREVALENCE

As the factors which impact on the population prevalence of nodular goiter, Grave’s disease and thyroid gland cancer, iodine deficiency, remote consequences of accident on the Chernobyl atomic station, population age structure and selection in modern conditions were studied. Differential fertility indexes, diseases prevalence and population age structure official statistic data were analyzed. It has been shown, that iodine deficiency expressiveness, consequences of accident on the Chernobyl atomic station, population age structure and selection are impact on the nodular goiter, Grave’s disease and thyroid gland cancer population prevalence.

Ground Waters of the Ukrainian Polessje (Woodlands) after the Accident at Chernobyl Atomic Station

To conserve ground waters in the Ukrainian Polessje under the condition of their poor protection on large areas against any contamination, including radioactive, it was necessary to evaluate initial contamination of both the waters themselves and the soil surface after the accident at Chernobyl atomic station. Investigations carried out at hydrotechnical systems of Polessje showed that ground waters contamination with caesium-137 doesn't exceed 2.37 × 103 Bq/m3, with strontium-90 being 8.88 × 103. It should be noted that on the surface the caesium radionuclide storage is from 100 to 250 times greater than that in water. Recent influence of Rovenskaya and Khmelnitskaya (near Rovno and Khmelnitsky) atomic stations located on Polessje upon ground waters is extremely difficult to define against the background of the contamination after the accident at Chernobyl station. Soils all over the territory had weakened absorption capacity; that is why gravitational water solutions, even of low concentration, will reach the ground water table and will stay in water for a long period of time. However forecasts show that considerable penetration of radionuclides into ground waters shouldn't be expected: the activity will not exceed maximum allowable values. A network of observation wells will give regular information and control ground water cleanness.

Groundwaters in Location of Chernobyl Atomic Station and Their Contamination with Radionuclides after the Accident

An evaluation of the influence of the Chernobyl Atomic Power Station (APS) accident upon ground waters of meliorative systems was carried out in a 30 km zone around the station. At the locations where elevation exceeds 5 m, the danger of contamination is minimum in the first 5 years, which is why emphasis was placed on flood plains of river valleys. In flood plains the ground water table (GWT) before the accident varied from 0.2 to 3.3 m with fluctuation from 0.5 to 3 m. Since the accident the systems haven't been in operation, the GWT fluctuation amplitude has decreased, the period of high water table has lengthened, and locations with secondary waterlogging have appeared. The ground waters chemical composition influencing the migration and sorption processes is typical for surplus soil water regions: mineralization is up to 1.0 g/l and pH from 6 to 7.5. Ground waters are not naturally protected here against radionuclide migration because of the small thickness of aeration zone, the sandy and loamy composition of soils, and their low adsorption. In 1989 contamination of ground waters with caesium-137 amounted from 2.26 × 102 to 2.413x 103 Bq/m3 and with strontium-90 it was from 37 Bq/m3 to 3.66 × 104 Bq/m3. Radionuclide migration towards ground waters depends not so much on surface contamination intensity as on soil physical and chemical characteristics in the aeration zone. It appeared that there were no direct dependencies between soil surface contamination intensity and that of ground waters contamination. It was noted that the amount of radionuclides depends upon the season. Analysis of radionuclides concentration in ground waters at different depths, considering soil surface contamination, allows us to define a relatively safe level of GWT with initial contamination; this information contributes to working out the measures on GWT lowering to optimum levels.