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Transfer of 137Cs from Chernobyl debris and nuclear weapons fallout to different Swedish population groups.

Data from measurements on the body burden of (134)Cs, (137)Cs and (40)K in various Swedish populations between 1959 and 2001 has been compiled into a national database. The compilation is a co-operation between the Departments of Radiation Physics in Malmö and Göteborg, the National Radiation Protection Authority (SSI) and the Swedish Defense Research Agency (FOI). In a previous study the effective ecological half time and the associated effective dose to various Swedish populations due to internal contamination of (134)Cs and (137)Cs have been assessed using the database. In this study values of human body burden have been combined with data on the local and regional ground deposition of fallout from nuclear weapons tests (only (137)Cs) and Chernobyl debris (both (134)Cs and (137)Cs), which have enabled estimates of the radioecological transfer in the studied populations. The assessment of the database shows that the transfer of radiocesium from Chernobyl fallout to humans varies considerably between various populations in Sweden. In terms of committed effective dose over a 70 y period from internal contamination per unit activity deposition, the general (predominantly urban) Swedish population obtains 20-30 microSv/kBq m(-2). Four categories of populations exhibit higher radioecological transfer than the general population; i.) reindeer herders ( approximately 700 microSv/kBq m(-2)), ii.) hunters in the counties dominated by forest vegetation ( approximately 100 microSv/kBq m(-2)), iii.) rural non-farming populations living in sub-arctic areas (40-150 microSv/kBq m(-2)), and iv.) farmers ( approximately 50 microSv/kBq m(-2)). Two important factors determine the aggregate transfer from ground deposition to man; i.) dietary habits (intakes of foodstuff originating from natural and semi-natural ecosystems), and ii.) inclination to follow the recommended food restriction by the authorities. The transfer to the general population is considerably lower ( approximately a factor of 3) for the Chernobyl fallout than during the 1960s and 70s, which is partly explained by a higher awareness of the pathways of radiocaesium to man both by the public and by the regulating authorities, and by the time-pattern of the nuclear weapons fallout during the growth season in Sweden.

Body Burden↗

[Permanent hypoparathyroidism due to thyroid cancer surgical procedures in patients exposed to radiation in the Chernobyl, Ukraine, nuclear reactor accident].

BACKGROUND AND OBJECTIVE: Postoperative hypoparathyroidism is a rare, but complex endocrine disorder. The purpose of this case series study was to evaluate the symptoms, signs and sequelae of the disease in a major homogeneous patient group after the Chernobyl accident in the Ukraine. PATIENTS AND METHODS: This study is based on a random sample of 25 patients with symptomatic permanent hypoparathyroidism after surgical procedures on the thyroid for carcinoma following the Chernobyl accident in May 1986. They underwent physical examination and their parathyroid hormone and calcium levels in serum were determined. The signs, symptoms and sequelae of their disease were systematically assessed by a validated specific questionnaire. The extent of individual distress by the symptoms and signs were analysed by using a Likert scale (points between 1 = no and 5 = maximal distress). RESULTS: In 14 patients (56%) (age at time of operation: 18.24 +/- 4.26 years) paresthesias occurred at least every third day. Very frequent general symptoms were joint pains and hair loss (in 17 patients / 68%). 19 patients (76%) had enamel defects, 17 (68%) increasingly dry skin since the operation. Psychical symptoms like excitability (20 patients / 80%) and depressed mood since the operation (16 patients / 64%) were strikingly frequent. The patients were affected more by dry skin (2,76 on the Likert scale) than by paraesthesias (2,56) or joint pains (2,68) and most of all by depressive mood (2.96) and excitability (3.38). 4 patients (16%) had kidney stones, while osteoporosis and osteosclerosis occurred in 7 (28%) respectively 3 persons (12%). 6 patients (24%) had cataracts and 3 (12%) had basal ganglia calcification. Interestingly, 1/3 of all patients had only non-characteristic symptoms of the disease consistent with a latent form of hypoparathyroidism. CONCLUSIONS: Our data partly show a severe form of hypoparathyroidism of very young persons in the Chernobyl region, a finding which strongly supports the need of exact diagnosis and interdisciplinary treatment options of this postoperative disorder.

Adolescent↗

Cancer consequences of the Chernobyl accident: 20 years on.

26 April 2006 marks the 20th anniversary of the Chernobyl accident. On this occasion, the World Health Organization (WHO), within the UN Chernobyl Forum initiative, convened an Expert Group to evaluate the health impacts of Chernobyl. This paper summarises the findings relating to cancer. A dramatic increase in the incidence of thyroid cancer has been observed among those exposed to radioactive iodines in childhood and adolescence in the most contaminated territories. Iodine deficiency may have increased the risk of developing thyroid cancer following exposure to radioactive iodines, while prolonged stable iodine supplementation in the years after exposure may reduce this risk. Although increases in rates of other cancers have been reported, much of these increases appear to be due to other factors, including improvements in registration, reporting and diagnosis. Studies are few, however, and have methodological limitations. Further, because most radiation-related solid cancers continue to occur decades after exposure and because only 20 years have passed since the accident, it is too early to evaluate the full radiological impact of the accident. Apart from the large increase in thyroid cancer incidence in young people, there are at present no clearly demonstrated radiation-related increases in cancer risk. This should not, however, be interpreted to mean that no increase has in fact occurred: based on the experience of other populations exposed to ionising radiation, a small increase in the relative risk of cancer is expected, even at the low to moderate doses received. Although it is expected that epidemiological studies will have difficulty identifying such a risk, it may nevertheless translate into a substantial number of radiation-related cancer cases in the future, given the very large number of individuals exposed.

Body Burden↗

Childhood leukaemia in Belarus, Russia, and Ukraine following the Chernobyl power station accident: results from an international collaborative population-based case-control study.

BACKGROUND: There is little evidence regarding the risk of leukaemia in children following exposure to radionuclides from the Chernobyl Nuclear Power Plant explosion on April 26, 1986. METHODS: This population-based case-control study investigated whether acute leukaemia is increased among children who were in utero or <6 years of age at the time of the Chernobyl accident. Confirmed cases of leukaemia diagnosed from April 26, 1986 through December 31, 2000 in contaminated regions of Belarus, Russia, and Ukraine were included. Two controls were matched to each case on sex, birth year, and residence. Accumulated absorbed radiation dose to the bone marrow was estimated for each subject. RESULTS: Median estimated radiation doses of participants were <10 mGy. A significant increase in leukaemia risk with increasing radiation dose to the bone marrow was found. This association was most evident in Ukraine, apparent (but not statistically significant) in Belarus, and not found in Russia. CONCLUSION: Taken at face value, these findings suggest that prolonged exposure to very low radiation doses may increase leukaemia risk as much as or even more than acute exposure. However the large and statistically significant dose-response might be accounted for, at least in part, by an overestimate of risk in Ukraine. Therefore, we conclude this study provides no convincing evidence of an increased risk of childhood leukaemia as a result of exposure to Chernobyl radiation, since it is unclear whether the results are due to a true radiation-related excess, a sampling-derived bias in Ukraine, or some combination thereof. However, the lack of significant dose-responses in Belarus and Russia also cannot convincingly rule out the possibility of an increase in leukaemia risk at low dose levels.

Age Distribution↗

Ecological half-time and effective dose from chernobyl debris and from nuclear weapons fallout of 137Cs as measured in different Swedish populations.

The fallout in Sweden of radiocesium from nuclear weapons tests during the 1960's (137Cs) and from the Chernobyl accident in 1986 (134Cs and 137Cs) has transferred to humans through different ecological pathways. Data from whole-body burden measurements of 134Cs, 137Cs, and 40K in various Swedish populations between 1964 and 2002 have been compiled. This database enables an evaluation of the temporal and geographical dependence of the transfer of radiocesium from ground deposition to humans and the associated absorbed dose. The body burdens of 137Cs gradually decrease after the peak values reached in 1965 from nuclear weapons fallout and in 1987 from the Chernobyl fallout, but at a varying rate depending on the population. Assuming a dual exponential decrease, a short-term component of typically 1-2 y and a long-term component of 5-10 y are found in urban populations in Sweden. Among reindeer herders and hunters the effective ecological half-time is mono-exponential with a half-time of 5-7 y. The estimated time-integrated effective dose to an individual during a period of 50 y from the Chernobyl fallout is, on average, approximately 10 mSv for reindeer herders, which is 10-100 times higher than the estimated dose received by urban populations in the three major Swedish urban areas (Malmö, Göteborg, and Stockholm).

Body Burden↗

Aberrant expression of E-cadherin and beta-catenin in association with transforming growth factor-beta1 in urinary bladder lesions in humans after the Chernobyl accident.

This study examines the molecular pathways of cell-cell communication in chronic inflammatory processes associated with long-term low-dose urinary bladder exposure to ionizing radiation in people without major disease living more than 19 years in radio-contaminated areas of Ukraine after the Chernobyl accident. Patterns of components of the E-cadherin/beta-catenin complex, and transforming growth factor-beta1 (TGF-beta1) and inducible nitric oxide synthase (iNOS) expression were immunohistochemically evaluated in urinary bladder biopsies from 52 males with benign prostate hyperplasia and 8 females with chronic cystitis (group 1). For comparison, 25 males and 6 females living in non-contaminated areas of Ukraine were also investigated (group 2). Fourteen patients with primary urothelial carcinomas, which were operated on before the Chernobyl accident, were included as a carcinoma group. Chronic proliferative atypical cystitis ('Chernobyl cystitis') was observed in group 1 patients. Foci of dysplasia and carcinoma in situ were found in 51 (85%) and 34 (57%) of the 60 cases, respectively. Chronic cystitis with areas of dysplasia was detected in only 4 (13%) cases of 31 group 2 patients. Statistically significant differences in immunohistochemical scores for TGF-beta1 in the urothelium and lamina propria, iNOS in the urothelium and both beta-catenin and E-cadherin in the cytoplasm were observed between groups 1 and 2 with marked expression in group 1. Furthermore, TGF-beta1 overexpression and alteration in E-cadherin/beta-catenin complexes in bladder urothelium might play a crucial role in urinary bladder carcinogenesis in humans exposed to long-term low-dose ionizing radiation.

Adult↗

Increase of regional total cancer incidence in north Sweden due to the Chernobyl accident?

STUDY OBJECTIVE: Is there any epidemiologically visible influence on the cancer incidence after the Chernobyl fallout in Sweden? DESIGN: A cohort study was focused on the fallout of caesium-137 in relation to cancer incidence 1988-1996. SETTING: In northern Sweden, affected by the Chernobyl accident in 1986, 450 parishes were categorised by caesium-137 deposition: < 3 (reference), 3-29, 30-39, 40-59, 60-79, and 80-120 kiloBecquerel/m(2). PARTICIPANTS: All people 0-60 years living in these parishes in 1986 to 1987 were identified and enrolled in a cohort of 1 143 182 persons. In the follow up 22 409 incident cancer cases were retrieved in 1988-1996. A further analysis focused on the secular trend. MAIN RESULTS: Taking age and population density as confounding factors, and lung cancer incidence in 1988-1996 and total cancer incidence in 1986-1987 by municipality as proxy confounders for smoking and time trends, respectively, the adjusted relative risks for the deposition categories were 1.00 (reference < 3 kiloBecquerel/m(2)), 1.05, 1.03, 1.08, 1.10, and 1.21. The excess relative risk was 0.11 per 100 kiloBecquerel/m(2) (95% CI 0.03 to 0.20). Considering the secular trend, directly age standardised cancer incidence rate differences per 100 000 person years between 1988 to 1996 and the reference period 1986-1987, were 30.3 (indicating a time trend in the reference category), 36.8, 42.0, 45.8, 50.1, and 56.4. No clear excess occurred for leukaemia or thyroid cancer. CONCLUSIONS: Unless attributable to chance or remaining uncontrolled confounding, a slight exposure related increase in total cancer incidence has occurred in northern Sweden after the Chernobyl accident.

Adolescent↗

[Long-term follow-up cytogenetic survey and biological dosimetry in persons evacuated from 30-km Chernobyl NPP zone].

The paper presents the results of the follow-up cytogenetic survey and biological dosimetry carried out in inhabitants of Pripiat' town and nearby villages, who were departured from the Chernobyl NPP 30-km exclusive zone during first days after the Chernobyl catastrophe. The unstable chromosome aberration level in inhabitants were significantly increased above control in terms up to 1 year after evacuation and declined gardually during next 14 years. In early period the cytogenetic damage frequency in evacuees showed no dependence on gender. The chromosome type aberration level appeared to be lower in young persons comparing with adults. The dicentrics plus centric rings yield had a positive correlation with duration of staying at Chernobyl zone. The average doses of protracted exposure were calculated from the dicentrics and centric rings yields; the dose estimations appeared to be 1.4 times higher in persons evacuated 3-11 days after the accident than that of in persons with shorter departure time. Uing the Bayesian analysis the probabilistic distribution of biological doses was constructed for the studied evacuees group. This distribution was characterized by a mean dose of 360 mGy, the modal doses of 200-450 mGy and 80% of probability density within the dose range 0-1000 mGy, that seems to be sufficient for considering the increased risk of late somatic radiation effects for this cohort.

Adolescent↗

[The retrospective cytogenetic dosimetry using the results of conventional chromosomal analysis in Chernobyl clean-up workers].

The paper presents the results of the cohortal biodosimetry carried out in 435 Chernobyl clean-up workers, who were surveyed with the conventional cytogenetic technique in terms from several days to 10 years after the end of their duties in the Chernobyl accident exclusive zone. An empirical model of the aberrant cell dynamics was utilized for the calculation of mean initial yields of dicentrics and centric rings in groups with different terms and duration of staying in the Chernobyl zone. Corresponding protracted irradiation doses estimated from aberration levels ranged from 79 to 670 mGy. The probabilistic distribution of the radiation doses was constructed by the applying the Bayesian analysis to initial individual chromosome exchange yields extrapolated to the exposure termination moment. This distribution was characterized by the mean dose about 460 mGy and maximum of probability density in the interval of 50-300 mGy. For the late somatic risk assessment in clean-up workers the probabilistic distribution of equivalentally-acute radiation doses was proposed; that had the mean value about 270 mGy, modal classes of 250-350 mGy and 99.8% of the probability density concentrated within the dose range from 0 to 1000 mGy.

Adult↗

[The radiological situation before and after Chernobyl disaster].

The nuclear reactor accident, which occurred on 26 April 1986 at Chernobyl, has been one of the greatest ecological disasters in human history. In our study we discussed the most recent data on the accident, and the natural and synthetic sources of radiation. According to the recent data, the air at Chernobyl had been contaminated with about 5300 PBq radionuclide activity (excluding rare gases), including 1760 PBq (131)I and 85 PBq (137)Cs. The highest radiation received by the liquidators (0.8-16 Gy), lower doses were received by the population which was evacuated or inhabited the contaminated areas (in which the level of (137)Cs activity deposited in the earth was 37 kBq/m(2)). In the European countries the highest mean radiation dose per year for the whole body in the first year after the accident was in Bulgaria (760 microSv), Austria (670 microSv) and Greece (590 microSv), while the lowest radiation dose was observed in Portugal (1.8 microSv) and Spain (4.2 microSv). In Poland the mean effective equivalent dose resulting from Chernobyl accident was 932 microSv and is close to the limited dose permitted in Poland, equalling 1 mSv/year. The highest radiation dose to thyroid was received by inhabitants of the states previously known as Bielskopodlaskie, Nowosadeckie and the north-east region of Poland. Lowest dose was received by inhabitants of the areas previously known as Slupski and Rzeszowski.

Air Pollutants, Radioactive↗

[The significance of cytogenetic investigation for the estimation of Chernobyl accident consequences].

The results of the cytogenetic investigation of people, which were exposed to radiation in the result of the Chernobyl NPP accident, were presented. Also the possibilities of the application of cytogenetic findings for dose estimations and for the prediction of the radiation influence consequences were examined. During the period of time since 1986 till 2004 the cytogenetic investigations of 1724 liquidators participating in the liquidation works after the Chernobyl accident were carried out. The radiation dose estimated by the frequency of dicentrics in 1986 was about 0.16 Gy. The doses for liquidators were determined by the frequency of translocations (FISH method) during the period from 1992 till 1995. For liquidators who worked in Chernobyl only in 1986 the average dose of radiation was about 0.19 Gy and for liquidators who worked repeatedly during the period from 1986 till 1995 - 0.39 Gy. There was shown that during the whole period of investigation (1986-2004) the frequency of dicentrics in peripheral blood lymphocytes was significantly higher than the control level. The cytogenetic investigation of Bryansk region inhabitants which was carried out in 1992-1994 discovered heightened value in 5 times than the control one. Findings are of great importance for the prediction of ill effects of radiation and for the development of sensitive criterions for early exposure disturbances in state of health.

Case-Control Studies↗

Thyroid carcinoma in children and adolescents in Ukraine after the Chernobyl nuclear accident: statistical data and clinicomorphologic characteristics.

BACKGROUND: The increase in the number of childhood thyroid carcinoma cases in Ukraine after the Chernobyl nuclear accident in 1986 prompted the development of a registry of thyroid carcinoma cases at the Institute of Endocrinology and Metabolism in Kiev. In the current study, the authors report the statistical data and clinicomorphologic features of the cases included in this registry. METHODS: To study the incidence, and age and gender distribution of thyroid carcinoma in Ukraine, the authors compiled complete clinical information from cases diagnosed and treated at the Institute of Endocrinology and Metabolism and statistical reports submitted to the registry from 27 regions of Ukraine. Morphologic features of the resected tumors were examined and were included in the database. RESULTS: During the 5 years preceding the Chernobyl nuclear accident, a total of 59 cases of thyroid carcinoma were identified in the birth to 18 years age group (25 in children age < or = 14 years and 34 in adolescents ages 15-18 years). Between 1986 and 1997, the total number of thyroid carcinomas in Ukrainian children and adolescents was 577 (358 children and 219 adolescents). Morphologically, the thyroid tumors overwhelmingly were papillary carcinomas, and the majority of these also showed a follicular and/or solid growth pattern. Lymph node metastases and other extrathyroidal spread were common, thus necessitating total thyroidectomy and lymph node dissections in many patients. CONCLUSIONS: Between 1990 and 1997, a significant increase in the incidence of thyroid carcinoma was noted in children and adolescents in Ukraine; the group most affected was comprised of the individuals who were age < or = 5 years in 1986 (the year of the Chernobyl nuclear accident). The largest number of cases occurred in patients living in areas of thyroid radiation doses of > or =0.50 grays. The morphologic features of those thyroid tumors suggest that they are aggressive tumors with a high frequency of lymph node metastases, venous invasion, and extrathyroidal spread.

Adolescent↗

Cancer consequences of the Chernobyl accident in Europe outside the former USSR: a review.

The accident which occurred during the night of April 25-26, 1986 in reactor 4 of the Chernobyl nuclear power plant in the Ukraine released considerable amounts of radioactive substances into the environment. Outside the former USSR, the highest levels of contamination were recorded in Bulgaria, Austria, Greece and Romania, followed by other countries of Central, Southeast and Northern Europe. Studies of the health consequences of the accident have been carried out in these countries, as well as in other countries in Europe. This report presents the results of a critical review of cancer studies of the exposed population in Europe, carried out on the occasion of the 10th anniversary of the Chernobyl accident. Overall, three is no evidence to date of a major public health impact of the Chernobyl accident in the field of cancer in countries of Europe outside the former USSR.

Adolescent↗

Characteristics of follicular tumors and nonneoplastic thyroid lesions in children and adolescents exposed to radiation as a result of the Chernobyl disaster.

BACKGROUND: In addition to the previously reported increase in incidence of thyroid carcinomas in Belarussian children after the Chernobyl disaster in April, 1986, benign thyroid lesions were also found to be increased in the exposed population. METHODS: A total of 60 follicular neoplasms and benign nonneoplastic thyroid lesions arising after the Chernobyl disaster in children and adolescents of 7 to 18 years of age were studied. RESULTS: The primary diagnoses in this series were follicular carcinoma in 1 (2%) case, follicular adenoma in 9 (15%), cystic adenomatoid nodule with papillae in 18 (30%), multinodular goiter in 18 (30%), diffuse hyperplasia in 2 (3%), diffuse hyperplasia with atypia and nodularity in 5 (8%), lymphocytic thyroiditis in 6 (10%), and thyroid cyst in 1 patient (2%). Additional histologic changes in thyroid glands from these patients were similar to those reported after radiation exposure, and included perifollicular fibrosis (72%), focal epithelial hyperplasia (73%), colloid accumulation (47%), follicular atrophy (33%), and cellular atypia (25%). Vascular abnormalities were found more often (75%) than previously reported in the thyroid gland after irradiation, and had a somewhat different appearance. They affected primarily medium-size arteries and were characterized by damage of the internal elastic lamina in addition to intimal fibrosis. CONCLUSIONS: The first case of thyroid follicular carcinoma in the exposed Belarussian children was diagnosed after a latent period of 6.5 years, as compared with 4 years of minimal latency for post-Chernobyl papillary carcinomas. Among benign thyroid lesions, cystic adenomatoid nodules of papillary type and diffuse hyperplasia with cellular atypia and nodularity seem to be commonly associated with radiation exposure to the thyroid gland.

Adenocarcinoma, Follicular↗

The Chernobyl catastrophe and population health: the state of knowledge in 1993.

This review describes the history and organizational structure of the Ukrainian Research Center for Radiation Medicine, which has studied the health effects of the Chernobyl incident since 1986. In five years of observation, the percentage of people defined as "healthy" was reduced by 1.6-2.2 times, and the general frequency of disease increased by 2.6 times. The most common disorders seen were of the pulmonary, central nervous system, circulatory and gastrointestinal systems. The observed medical effects of radiation from Chernobyl are greater than might be expected, given the estimates of radiation dose released. This discrepancy may result from an underestimation of the radiation dose or a failure to account for compounding the interaction with factors other than radiation. Ongoing surveillance of the consequences from the Chernobyl accident must take place to provide new information on the health effects of accidental radiation exposure in humans.

Government Agencies↗

Design and analysis of epidemiological studies of excess cancer among children exposed to Chernobyl radionuclides.

Within the last decade, a substantial amount of attention has been devoted to etiological research on the association between exposure to fallout radionuclides from the Chernobyl accident and radiation-induced late effects (cancer) among children. A majority of the studies completed to date have been of the descriptive type, which only correlate average population exposure with average rate of cancer incidence as a function of calendar period. Since individual dosimetry is not performed in descriptive studies, it is unclear whether exposure precedes the development of cancer and a final decision cannot be made regarding the association between radiation exposure and cancer. This paper reviews the background epidemiology and outlines an analytical study design that is needed to clarify the unclear association between Chernobyl fallout exposure and childhood cancer. We discuss the essential elements of an analytical case-control design such as genetic predisposition, vital statistics, sample size and power determinations, ascertainment of cases and controls, and phenomenological dose modeling to establish individual doses. Examples such as cytogenetic biodosimetry, medical radiation dosimetry, and cytogenetic characterization of leukemia to minimize exposure and diagnostic misclassification are provided. We recommend the analytical methods described in this paper for studying the role of Chernobyl radionuclides and development of childhood cancer.

Adolescent↗

Radioactivity in total diet before and after the Chernobyl reactor accident. The situation in the Federal Republic of Germany.

Radioactivity in total diet samples (1-day rations of adults) has been determined in the Federal Republic of Germany since 1960. Average intake of cesium-137 was 8.9 Bq per day and per person (Bq/d.p) in 1964, 0.15 in 1985, 4.2 in 1986, 7.2 in 1987, and 2.0 in 1988. Cesium-134, not measureable in pre-Chernobyl fallout, averaged 2.0 Bq/d.p in 1986, 3.0 in 1987, and 0.6 in 1988. Intake of strontium-90 was in the same range as in the years preceding the Chernobyl accident. It is estimated that the total effective equivalent dose for adults due to ingestion of Chernobyl-released radionuclides, including iodine-131, will be 0.14 +/- 0.08 mSv.

Accidents↗

[The radioecology of the grapevine. 2. Effects of the nuclear reactor accident in Chernobyl on the radioactivity in the soil, leaves, grapes and wine].

Natural (tritium, 14C, 40K, 226Ra) and man-made radionuclides (90Sr, 134Cs, 137Cs) were determined in soil (top 30 cm), vine leaves, grapes and wine in eight locations of the most important viticultural regions in the Federal Republic of Germany. The results obtained in 1983-1985 have been published previously. Part II of this study presents results obtained in 1986 and 1987, i.e. after the reactor accident at Chernobyl in the Soviet Union. The mean content of 137Cs before (after) Chernobyl was 4 (9) Bq/kg dry matter in soil, 0.07 (3) Bq/kg fresh matter in leaves, 0.02 (0.4) Bq/kg in grapes, and 0.008 (0.9) Bq/L in wine. As compared with 1986, distinctly lower levels were found in leaves, grapes and wine in 1987. In 1986 the content of 134Cs was about half that of 137Cs. Owing to its shorter half-life, 134Cs was below the detection limit in many of the 1987 samples. Transfer factors such as from soil to leaves and from soil to grapes for caesium agreed well in 1983-1985 and 1987, but showed considerable deviations in 1986, due to the ubiquitous contamination of the environment. Results of 90Sr determinations confirmed other reports showing this radionuclide to be a very minor contributor to the total radioactivity released at Chernobyl. No effect of the reactor accident on levels of the other radionuclides was detected.

Accidents↗