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PubMed1997

Perinatal mortality in Germany following the Chernobyl accident.

Perinatal mortality in Germany was investigated with respect to a possible relationship to the nuclear accident in Chernobyl on April 26, 1986. Using annual data of perinatal mortality, a trend analysis based on an appropriately chosen statistical model was performed which showed a significant increase in 1987. In addition, we calculated the cesium concentration in women's bodies using data of the cesium concentration in milk. We found two peaks of cesium concentration that were associated with the observed two peaks of monthly perinatal mortality data with a delay of 7 months.

Cesium Radioisotopes↗
PubMed1997

Leukaemia and thyroid cancer in emergency workers of the Chernobyl accident: estimation of radiation risks (1986-1995).

This work focuses on the direct epidemiological assessment of the risks of radiation-induced leukaemia and thyroid cancer in emergency workers (EW) after the Chernobyl accident. The Russian National Medical Dosimetric Registry (RNMDR) contains data for 168,000 EW as of January 1, 1996. The analysis relates to 48 leukaemias and 47 thyroid cancers, diagnosed and verified. Radiation risks are estimated by comparing the EW data with national data for a male population of the same age distribution. For leukaemia, an excess relative risk per Gy (ERR/Gy) of 4.30 (95% CI: 0.83, 7.75) is obtained, while the excess absolute risk per 10(4) person-years (PY) Gy (EAR/10(4)PY Gy) is found to be 1.31 (95% CI: 0.23, 2.39); for thyroid cancer an ERR/Gy of 5.31 (95% CI: 0.04, 10.58) is obtained, and an EAR/10(4)PY Gy of 1.15 (95% CI: 0.08, 2.22).

Adult↗
PubMed1997

Thyroid dose reconstruction for the population of Belarus after the Chernobyl accident.

An 131I environment transfer model--adapted for Belorussian conditions--was applied to estimate thyroid doses for different population groups. For this purpose the available data were analysed and the important radioecological parameters assessed i.e. (a) the elimination rate of 131I from grass due to weathering and growth dilution, (b) the initial interception of 131I by vegetation, (c) the transfer coefficient for 131I from grass to cow's milk, (d) the yield to pasture grass and (e) the milk consumption rate. Additionally, the influence of applied countermeasures has been taken into account, such as the interruption of locally produced milk consumption, and the appropriate correction factors have been estimated. As a result, the average age-dependent thyroid doses were assessed for the Belorussian population. The highest average doses in children (> 1 Gy) have been estimated for the Bragin, Khoiniki, Narovlia and Vetka raions of the Gomel oblast. The thyroid exposure tends to decrease from the southeastern (closest to the Chernobyl nuclear power plant areas) to the northwestern part of the republic. When comparing the assessed thyroid doses with estimates derived from direct 131I activity measurements in thyroids (for the locations with more than 15 direct measurements), the results agree fairly well. The model calculation may perhaps overestimate thyroid doses of the population residing in the settlements of the central and northern parts of Belarus, distant from the areas with direct measurements of 131I activities in soil, grass and milk. These thyroid dose estimates may serve as a basis for further epidemiological studies and risk analyses.

Adolescent↗
PubMed1997

Cancer risks in the Kaluga oblast of the Russian Federation 10 years after the Chernobyl accident.

Cancer morbidity and mortality were studied in areas of the Kaluga oblast contaminated with radionuclides. The main objective of the study was to assess the influence of radiation exposure on existing levels of cancer morbidity and mortality. Time trends and relative population risks were analysed. Based on this analysis, it was concluded that the current levels of morbidity from cancers among the populations residing in the studied areas were primarily a result of a complex of factors which predated the exposure from the Chernobyl accident. However, there seems to be an unfavourable trend concerning malignant neoplasms of the respiratory organs for women residing in the contaminated areas. To date, no statistically significant effect of radiation on cancer morbidity (except for thyroid cancer in women) has been noted. The levels of cancer morbidity and mortality in the contaminated areas generally reflect the changes in cancer incidence in the oblast as a whole. The findings are consistent with international data on latent periods for the induction of radiogenic cancers and the biological effects for similar levels of exposure to populations residing in contaminated territories. Further studies are necessary in order to monitor possible effects that are related to the accident.

Female↗
PubMed1997

Thyroid cancer incidence in the Ukraine after the Chernobyl accident: comparison with spontaneous incidences.

The thyroid cancer incidence in the Ukraine among those born in the period 1968-1986 was analyzed with the aim to identify the enhancement due to the Chernobyl accident. Since any Ukrainian data referring to the time period before the accident are scarce and the variation of spontaneous incidences in other countries is immense, the Ukrainian incidences in the period 1986-1989 were used to estimate the baseline risk. Following 1990, the incidence in the southern part of the Ukraine increased by about 30%, independent of age. In the other parts the increase of the incidence depended on age at exposure. In the age group of 9-year-old children, the incidences in three regions defined as the 'high-dose area', the northern, and the middle oblasts, increased by factors of 50, 20, and 6, respectively. These rates (1991-1995) are well above spontaneous rates in other countries. In the age group of 17-year-old juveniles, the incidence increased by a factor of 6 for the 'high dose area' and in the three northern oblasts, whereas in the nine 'middle' oblasts it was similar to the incidence of the 'southern' Ukraine. These rates are within the range found in other countries.

Adolescent↗
PubMed1998

Thyroid dose and thyroid cancer incidence after the Chernobyl accident: assessments for the Zhytomyr region (Ukraine).

In the Zhytomyr region, about 52,000 measurements of the 131I activity in thyroids were performed. On the basis of these measurements, individual doses have been assessed for the people monitored and age-dependent average doses have been estimated for those settlements with more than 11 direct measurements. In order to estimate the pattern of thyroid exposure in the Zhytomyr region, these doses have been interpolated or extrapolated to population groups who were not monitored during May-June 1986. For this purpose, a model has been developed based on a correlation between thyroid dose estimates with the 137Cs deposition and the co-ordinates of the settlements relative to Chernobyl. Collective doses of people who were born in the years 1968 to 1986 were calculated. The radiation-induced thyroid cancer incidence in the period 1991 to 1995 was assessed by subtracting the spontaneous incidence from the observed incidence. The result is considerably lower than that observed in longer periods after external exposures. Possible reasons for this difference are discussed.

Adolescent↗
PubMed1998

Health consequences of Chernobyl and other radiation accidents. Report on the European Union Cluster Contractors' workshop (San Miniato, Italy, 17-22 June 1997).

The Radiation Protection Research Unit of the European Commission has been supporting collaborative research projects on the radiological consequences of the Chernobyl accident since 1991. However, in the Fourth Framework Programme of the Commission which started in 1996, the collaboration with scientists in the former Soviet Union has been placed on a different footing, and the programme has been expanded to include other regions, especially in Russia and Kazakhstan, where previous nuclear incidents have led to the exposure of workers and the local populations and to widespread radioactive contamination. There are 15 projects on health-related studies in the newly started programme, and in order to improve the collaboration between the different scientists working in these projects a Cluster Contractors' Meeting was organised in San Miniato, Italy, in June 1997 with the participation of some 50 scientists from the European Union (EU) and the Newly Independent States (NIS). This report summarizes the different topics, including molecular biology and treatment of childhood thyroid cancer, various epidemiological studies and dose reconstruction, which were discussed at the meeting and which form the major projects in the new collaborative programme.

Chromosome Aberrations↗
PubMed1998

Infant leukemia in Belarus after the Chernobyl accident.

Petridou et al. [1] have reported an increase in infant leukemia in Greek children born between 1/7/86 and 31/12/87 and have linked this increase to in utero radiation exposure due to the Chernobyl accident. Subsequently, Michaelis et al. [2] have reported a similar trend for Germany but found that it was not correlated to the levels of contamination. For Belarus, which was much more severely affected, a similar but much weaker trend is found.

Cohort Studies↗
PubMed1998

Association of Chernobyl-derived 239+240Pu, 241Am, 90Sr and 137Cs with different molecular size fractions of organic matter in the soil solution of two grassland soils.

Radiocesium is normally bound only rather weakly and unspecifically by humic substances, in contrast to the actinides Pu and Am. Recently, however, it was observed that fallout 137Cs in the soil solution from an Of-horizon of a podzol forest soil (slightly decomposed plant material) was associated essentially only with one single size fraction of the humic substances. In deeper soil layers with well humified material (AOh-horizon), radiocesium was associated with all size fractions of the dissolved organic matter (DOM). To examine whether this unexpected behaviour is also observable for DOM isolated from other soils, we determined the association of fallout 137Cs, 90Sr, 238Pu, 239+240Pu and 241Am with various size fractions of DOM from in situ soil solutions isolated from two layers (0-2 cm and 2-5 cm) of two grassland soils (a soddy podzolic soil and a peat soil) within the 10 km zone of the nuclear reactor at Chernobyl (Ukraine). The four size fractions of DOM as obtained by gel filtration of the soil solution were (mean nominal molecular weight in daltons): fraction I: > or = 2000, fraction II: 1300; fraction III: 560, fraction IV: inorganic compounds. The results for the well humified DOM (humus accumulation horizon of podzol, deeper layer of peat soil) showed that Pu and Am are essentially associated with the high molecular weight fractions, while Sr is present only in the 'inorganic' fraction. Radiocesium is found in all the size fractions separated. A quite similar pattern was also found for Pu, Am, and Sr in the soil solution from only slightly decomposed plant material (0-2 cm of peat soil), but not for radiocesium. This radionuclide was again essentially only observable in one single low molecular weight fraction of DOM. The above results thus support our recent observations in the different horizons of a forest podzol mentioned above, even though no reason for the different binding of radiocesium by well humified soil organic matter and by only slightly decomposed plant material can be given at present. The data demonstrate, however, that information on only the total amount of a radionuclide in the soil solution will not be sufficient to interpret or predict its fate adequately in the soil.

Americium↗
PubMed1998

Measurement of resuspended aerosol in the Chernobyl area. Part III. Size distribution and dry deposition velocity of radioactive particles during anthropogenic enhanced resuspension.

During anthropogenic activities, such as agricultural soil management and traffic on unpaved roads, size distribution measurements were performed of atmospheric particulate radionuclides at a site in the Chernobyl 30-km exclusion zone. Analysis of cascade impactor measurements showed an increase of the total atmospheric radioactivity. In the cases of harrowing by a tractor and traffic on unpaved roads, a common shape of the size distribution was found with two maxima, the first in the 2-4 microm range, the second in the 12-20 microm range. The size distributions were compared to measurements during wind-driven resuspension. Particle number concentration measurements with an Aerodynamic Particle Sizer showed a dynamic dependence of the particle concentration in different size ranges on anthropogenic action. The increase of the mean concentration was for the large particles more than one order of magnitude higher than for fine particles during anthropogenic enhanced resuspension. From the measurement of the mass concentration, the radioactive loading could be estimated. An enrichment of radionuclides on resuspended particles (compared to soil particles) was found, with the highest enrichment for large particles. Micrometeorological considerations showed that large particles may frequently be subject to medium range transport. The dry deposition velocity was measured; the mean value of 0.026 m s(-1) +/- 0.016 m s(-1) is typical for 6-9 microm diameter particles.

Aerosols↗
PubMed2001

Radiation sclerosing proliferative atypical nephropathy of peritumoral tissue of renal-cell carcinomas after the Chernobyl accident in Ukraine.

After the Chernobyl accident, the morbidity of renal-cell carcinomas in Ukraine increased gradually from 4.7 to 7.5 per 100,000 of the total population. Cesium 137 (137Cs) is responsible for 80-90% of the internal radioactivity in people living in radiocontaminated areas of Ukraine, and 90% of 137Cs is eliminated through the kidneys. Histological and immunohistochemical study of proliferating cell nuclear antigen (PCNA) and K-ras protein was performed in peritumoral kidney tissues of 167 Ukrainian patients (groups I-III, according to varying degrees of internal exposure to radiation), and of 85 analog Spanish patients, as a control group. Our data showed in the majority of Ukrainian patients a radiation sclerosing proliferative atypical nephropathy (RSPAN) in association with an increase in the incidences of tubular epithelial nuclear atypia and carcinoma in situ (CIS). Areas of epithelial nuclear atypia and CIS of the cortex and medulla showed significant PCNA expression with means of extent as 12, 14, and 15% of stained nuclei in groups I, II, and III respectively. K-ras expression of the same areas occurred in 67, 87, and 85% of cases in groups I, II, and III respectively. The present study points to a strong relationship between the long term of low-dose radiation exposure of the Ukrainian population and the development of RSPAN as a possible precursor of malignancy. In addition, it confirms the possible initiator, promoter, or progressor role of chronic low-level radiation of renal human carcinogenesis in Ukraine.

Adult↗
PubMed1997

Effects of low level radiation from the Chernobyl accident in a population with iodine deficiency.

UNLABELLED: To determine the effects of low dose radiation from 131I and 137Cs resulting from the Chernobyl disaster on the expression of endemic goiter in children, we studied children in regions with and without evidence of radiocontamination but comparable iodine insufficiency. We included 89 children in the study (radiocontaminated) region (SR) and 116 in the control region (CR) because they were either fetuses, infants, or pre-adolescents at the time of exposure. We evaluated thyroid dimensions by clinical examination and ultrasound; thyroid function by hormonal levels, and thyroglobulin measurement; histology of the thyroid by fine needle aspiration; and thyroid autoimmunity. SR subjects had 5 times the frequency of thyroid enlargement as those from CR, greatest in the younger patients. There were no instances of clinically apparent thyroid dysfunction. Antithyroid microsomal and antithyroglobulin antibodies were present in a markedly greater percentage of SR subjects. Fine needle biopsy demonstrated greater cellular proliferation in samples from SR. CONCLUSIONS: We have demonstrated findings of autoimmune thyroid disease at markedly increased frequency in a population of children with poor iodine nutriture who were exposed to low level radiation, compared to a more iodine deficient population not so exposed. These results suggest that low level radiation may induce thyroid gland changes in children who have inadequate iodine intake nutriture and reinforce the importance of adequate dietary iodine.

Adolescent↗
PubMed1992

Chernobyl operators: criminals or victims?

The blame for the 1986 Chernobyl disaster has been variously attributed to the operating personnel, the plant management, the design of the reactor, and the lack of adequate safety information in the Soviet nuclear industry. This paper considers a number of design faults, operational shortcomings and human errors that combined in the accident. It examines the sequence of events leading up to the accident, design problems in the reactor and cooling rods, and the course of the accident itself. It considers the ergonomics aspects, and expresses the view that the main cause of the accident was inadequate human-machine interaction. Finally, it stresses the continuing inadequacies of the Soviet nuclear system, and emphasizes that unless the ergonomics lessons are fully learned, a similar disaster could still occur.

Journal Article↗
PubMedDate not supplied

Chernobyl radiocaesium in an upland sheep farm ecosystem.

Following the deposition of radiocaesium from the Chernobyl accident the movement and slaughter of sheep in upland areas of west Cumbria, Scotland and Wales was restricted. Studies on the radioecology of Cs-137 and Cs-134 have been conducted at a farm within the affected area of west Cumbria since July 1986. The radiocaesium activity of upland sheep was found to decline when they were brought on to the farms' enclosed pastures and rise when they were returned to the open fell, where the radiocaesium content of vegetation has remained higher than on the pastures. The Cs-137 activity concentration of mixed grassland vegetation samples from the fell has declined over the study period, whereas the Cs-137 activity of ewes whilst grazing on the fell was higher in summer of 1987 than in autumn 1986. A number of factors which may have contributed to this discrepancy were investigated and are discussed. It is suggested that husbandry changes would be effective in reducing the number of lambs leaving the restricted area with radiocaesium activities over the limit (1000 Bq/kg fresh weight Cs-134 + Cs-137) set by the United Kingdom authorities.

Accidents↗
PubMed1994

Dicentric and translocation analysis for retrospective dose estimation in humans exposed to ionising radiation during the Chernobyl nuclear power plant accident.

Chromosome analyses were carried out in peripheral blood lymphocytes obtained between September 1991 and March 1992 from 15 persons exposed to ionising radiation during the Chernobyl nuclear power plant accident. At present, all are being treated for symptoms of the delayed stage of the cutaneous radiation syndrome. Biological dose-equivalent estimates were determined, either by measuring the frequency of dicentric and ring chromosomes in first division unstable cells from conventional preparations (Qdr method), or by measuring the frequency of stable translocations using two-colour fluorescence in situ hybridisation (FISH) with composite whole chromosome-specific DNA libraries for human chromosomes 1, 4 and 12 (chromosome painting) and a degenerate alpha-satellite pancentromeric DNA probe. With both methods fairly comparable individual estimates between 1.1 and 5.8 Gy were obtained for 12 of 15 individuals. Three individuals exhibited no elevated aberration frequencies. Perspectives and limitations of chromosome painting for dose reconstruction of past radiation exposures are discussed.

Cells, Cultured↗
PubMed1995

Do human lymphocytes exposed to the fallout of the Chernobyl accident exhibit an adaptive response? 2. Challenge with bleomycin.

The present study concerns the possible adaptive response, induced in vivo by a continuous exposure to ionizing radiations, to a challenge treatment with the radiomimetic glycopeptide bleomycin (BLM). Lymphocytes from children contaminated as a consequence of Chernobyl accident were treated for the last 5 h of culture with 2.5 micrograms/ml BLM. The induced chromosome damage was significantly lower than that found with the same treatment in lymphocytes from control children. This hyposensitivity to BLM was still present if, 1 h after the addition of the drug, inhibitors of the enzymes involved in DNA repair, such as 3-aminobenzamide (2 mM), or aphidicolin (0.4 microM) or 3-dideoxythymidine (5 mM) were added to the cultures. The resistance to BLM in lymphocytes from contaminated children seems to be related to a mechanism upstream in respect to the activities of enzymes involved in the DNA repair and specifically linked to the action of this drug. This is consistent with the different response found when the cells were challenged with ionizing radiation in vitro, as reported in the accompanying paper (L. Padovani, L. et al. (1995) Mutation Res., this issue).

Adaptation, Physiological↗
PubMed1995

Do human lymphocytes exposed to the fallout of the Chernobyl accident exhibit an adaptive response? 1. Challenge with ionizing radiation.

Several studies suggest that cells appear to become less susceptible to the induction of radiation damage, and in particular of chromosome and chromatid aberrations in short-term cultures of human lymphocytes, when a challenge exposure to ionizing radiation is preceded by a low 'adaptive' dose. Contradictory results have been reported on the conditions under which the phenomenon can be evidenced. In the present work, circulating lymphocytes of 13 children contaminated from the fallout after the Chernobyl accident were tested for their capability to exhibit an adaptive response in experiments in which the challenge dose was administered to stimulated lymphocytes in the S-G2 phase. Furthermore, the possible influence of 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase, was also investigated. Our results indicate that, at least in the instance of the end-point here used (chromosome and chromatid aberrations, the former resulting possibly from the Cs burden), human lymphocytes, chronically exposed to low doses from fallout, do not exhibit any decreased susceptibility to ionizing radiation. However, as reported in the accompanying paper, the same samples appear to show an 'adaptive' response when exposed to a challenge treatment with bleomycin (B. Tedeschi et al., 1995, this issue).

Adaptation, Physiological↗
PubMed1996

Yearly variation of spontaneous somatic mutation frequency in the stamen hairs of Tradescantia clone KU 9 grown outdoors, which showed a significant increase after the Chernobyl accident.

Scoring of spontaneous somatic pink mutation frequency in the stamen hairs of Tradescantia clone KU 9, a heterozygote for flower color (blue/pink; the blue color being dominant), was carried out for 11 years on plants grown outdoors, during the period of May 11-31 (for 3 weeks) in every year from 1982 to 1992. Weekly and yearly variations of the spontaneous mutation frequency were observed, and such variations could mostly be correlated to the difference in temperature. That is, the mutation frequency was generally higher in the weeks and years when the temperature was relatively low, showing the strongest negative correlation with the average minimum temperature. The variations were also correlated to the diurnal temperature difference, the mutation frequency being higher with larger diurnal temperature difference in general. However, the mutation frequency observed in 1986 was exceptionally higher than that expected from the temperature for this year, and was very significantly higher than for other years. The scoring of mutation frequency was thus continued in 1986 for an additional 4 weeks (June 1-28), and it was confirmed that such higher mutation frequencies lasted for 6 weeks in total. The exceptionally high mutation frequency seemed to be related to the radioactive fallout which occurred in early to mid May of 1986, even in Japan, after the serious nuclear reactor accident at Chernobyl, and also to the biological concentrations of radioactive nuclides which subsequently occurred, although it was difficult to conclude this definitely. The mutation frequency in 1987 was second highest, and was also significantly higher than the lowest mutation frequency observed in 1990.

Climate↗