Our objective was to explore whether the radiation fallout in Finland after the accident at the Chernobyl nuclear power plant in April 1986 led to an increased incidence of trisomy 21. In this geographic and temporal cohort study, the country was divided into three zones according to the amounts of radioactive fallout and internal radiation caused by two cesium isotopes. The 518 cytologically verified cases of trisomy 21 were divided into a control group (conceived before the accident), and a study group of children whose expected dates of birth were in the post-accident years 1987-1988, i.e., pregnancies commenced after May 1986. The cases were also divided into three subgroups according to the zones of radiation. There were no significant differences in prevalence of trisomy 21 between the control and study groups nor between the three zones in spite of the significant differences in the levels of radiation and in the body burden that prevailed throughout the study period. Power estimates showed that in the two zones of lower radiation, an increase of 0.5% in the prevalence would have been detected with a power of 0.85, and in the somewhat smaller zone of the highest radiation, with a power of 0.70. The study lends no further support to the view that the low radiation fallout in western Europe would have been causally associated with trisomy 21.
The chromosome dicentric aberrations in the lymphocytes and levels of antibodies to human thyroid microsomal antigen in the serum of the children lived in the area of Bryansk Province suffered from the Chernobyl accident was examined. Correlation between those tests was not estimated: the autoantibodies were revealed in group with dicentrics and without those in 4.0% and 4.5% of cases correspondingly. Antimicrosomal antibodies were revealed more frequently (5.0%) and in higher titers in the children from the more polluted Bryansk Province than in those from Kaluga Province (3.1%). These data can testify about the role of inside radiation of thyroid gland in appearance of autoimmune thyroiditis signs.
The callus culture of Nicotiana tabacum L. was obtained from the plants chronically irradiated in 10 km zone of Chernobyl Atomic Power Station. The tobacco plants in 10 km zone of Chernobyl during the vegetation period exposed to irradiation with the average dose rate of 0.36 mA/kg (5 mP/h). The total absorbed dose was approximately 0,31 Gy. The morphogenetic analysis of this culture shows a considerable decrease of regeneration index and callus weight.
A selected group of about 20 male researchers at the NIRS that reside in Chiba, Japan, was measured for total body content of radiocesium and 40K every 3 mo from February 1986 to May 1991. A whole-body counter at the NIRS was used to measure their radioactivity in a scanning mode of 5 cm min-1 in a shielded iron room with walls 20 cm in thickness. A maximum radiocesium level of 59 Bq was observed in May 1987. The annual change in the body burden decreased with an apparent half-time of 1.8 y after May 1987. The period of five years was sufficient to eliminate the effects of the accident in this group. Even in the most contaminated period, the dose from radiocesium was below 2 microSv y-1. The cumulative dose for 5 y was estimated to be 5.6 microSv, which is nearly equal to the total dose to the Japanese people caused by the artificial radionuclide fallout for the first year following the accident. It is much smaller than the committed dose of 82 microSv for internally deposited 137Cs resulting from nuclear explosions in 1961 and 1962 and the annual dose of 170 microSv from internal 40K. No detectable health risk was expected for the present group.
About a two years later after the reactor accident in Chernobyl we carried out a three-year cytogenetical study of children, dwelling in two regions of Ukraine where the radiation fallout occurred. Chromosome analyses of these individuals have shown a significant increase of the frequency of aberrant cells and chromosomal type aberrations in comparison to the control. We have discovered the increase of the level of chromosomal type aberrations, extension in spectrum of complicate aberrations of chromosome (dicentrics, rings and exchange aberrations) with the years and the increase with the years a share of children with various chromosomal abnormalities. Analyses of sister chromatid exchanges (SCE) and a replication index (RI) show a significant increase of RI meaning with the years in comparison to the control. The SCE frequency didn't altered as compared to the control during different years of investigation.
The permissible level of a radionuclide mixture, resulted from the Chernobyl burst, in the human being lungs was determined for two kinds of compounds: absolutely insoluble compounds and soluble compounds in the state of equilibrium. For this purpose the data were used concerning the radionuclide composition and aerosol disperse in lower atmosphere which were obtained by the Department for Dosimetric Control (NPO "Pripiat'"). The results of measurements of 137Cs content taken by the use of human radiation spectrometer (HRS) needed an adequate estimation: low level of 137Cs in the human lungs and body within the Chernobyl NPP, zone does not guarantee radiation security. The notion "permissible content" and the possibility of using thereof in the individual dosimetric control are discussed.
The paper describes the image of radiation menace. Basic differences in image parameters are revealed for some population groups. The psychological levels of the image are regarded as psychosocial phenomena. Some specific psychological consequences of mental regression are outlined in the paper.
The children living in 4 regions of Russia contaminated as a result of the Chernobyl catastrophe were investigated. The control group consisted of the children of 2 regions which did not undergo this influence. The investigations were made 1-3 years after the catastrophe took place. An increase of etiologically non-clear asthenic-vegetative disorders was determined in the regions of radiation contamination. They were observed mainly among the children who had light residual organic cerebral deficiency. The authors cannot exclude the impact of the psychogenic factors.