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PubMed1995

EEG power mapping, dipole source and coherence analysis in Chernobyl patients.

EEG power mapping, coherence analysis, source localization of epileptiform activity and psychoneurological investigations were performed in 100 patients (males, 25-45 years old, right-handed), who took part in the cleaning of the Chernobyl disaster in 1986-1987, and compared with a control group (healthy persons of the same age). Neuropsychological studies showed autonomic, endocrine, emotional and other disorders in all patients. About 70% of all patients had paroxysmal EEG activity and intermittent seizures sometimes associated with loss of consciousness. EEG power mapping showed higher than normal levels of alpha- and theta-bands power, mainly in the frontal and central areas in the one group of patients. In others, power was lower especially in alpha-band. Paroxysmal waves of alpha- and theta-bands had localization of dipole sources at deeper near midline levels, and as a rule with a shift to the right hemisphere. Paroxysmal beta-waves demonstrated sources of a diffuse character at a more basal level with a shift to the left hemisphere. Interhemispheric coherences had lower values in the frontal and higher in the central leads than in healthy persons. Intrahemispheric coherences were decreased in the left hemisphere and increased in the right, opposite to that in controls.

Adult↗
PubMed1993

Environmental behaviour of radionuclides deposited after the reactor accident of Chernobyl and related exposures.

Several radioecological experiences with isotopes of ruthenium, iodine, caesium and barium, obtained after the reactor accident of Chernobyl, are reported. It was found that for a wet deposition barium was the element with the highest retention on grass. The retention of caesium was lower by a factor of 1.6, retention of iodine by a factor of 2.4 and retention of ruthenium by a factor of 3.5. Former data on the caesium transport in cereals from leaves to grain were confirmed. Depending on the conditions the iodine transfer factor for milk varied between 0.002 and 0.007 d.kg-1. The caesium transfer factor for milk was (0.003 +/- 0.0006) d.kg-1 and was found to be relatively constant in the years 1986-1988. In 1991, the values were higher by a factor of 2-5. Radioecological model results of whole-body burdens in Southern Bavaria showed a reduction of the caesium ingestion doses due to countermeasures and spontaneous changes of consumption habits in the first 2 months by a factor of 5 and till the end of 1987 by a factor of 1.5. The model results agree well with the range of measured whole-body burdens. One month after the deposition, the external exposures in urban environments due to ruthenium, caesium and barium isotopes were found to be reduced by a factor of 2, compared with open lawns, in the case of iodine the reduction was even a factor of 2.5. External exposures of a population group from the Munich area were determined by thermoluminescence dosimetry. The results are in accordance with the spectral measurements of external dose rates in urban environments.

Accidents↗
PubMed1992

Transfer factor of 131I from the fallout to human thyroid dose equivalent after the Chernobyl accident.

A similar pattern of variation with time in observed maxima of daily dose equivalent rates in human thyroids (TD - microSv.d-1) and of daily fallout radioactivities (FR - kBq.m-2) has been found after the Chernobyl accident. An estimate of the time-lag between the maxima in TD lines and the preceding FR peaks was made of about seven days for adult and nine days for juveniles. Applying this time-lag it was possible to estimate transfer factors from the fallout to thyroid dose equivalent: the highest estimated values were 221 microSv/kBq.m-2 for adult and 641 microSv/kBq.m-2 for juvenile thyroids. These values differ from those published by UNSCEAR (United Nations 1988), which have been calculated for various regions of Czechoslovakia, from ingestion and inhalation intake estimates. A broad variation of transfer factor values could be expected to result from such transfer calculations using ingestion and inhalation estimates. The findings also support the concept of a need for prolonged iodine prophylaxy after emissions of radioiodine into the environment.

Accidents↗
PubMed1996

Scientific recommendations for the reconstruction of radiation doses due to the reactor accident at Chernobyl.

In the years after the Chernobyl reactor accident, many studies of the radiation exposure levels and resulting health effects in the countries of the CIS have been conducted. The increasing incidence of childhood thyroid cancers in Belarus and Ukraine has stimulated worldwide multi- and bilateral cooperations with those countries and Russia in order to optimize benefits for those directly affected, but also to enlarge current knowledge of the consequences of reactor accidents. An international workshop on dose reconstruction was held in Bad Honnef, June 6 to 9, 1994, to address the problems which arise in dose reconstruction. The main objectives of this workshop were to bring together the best professional expertise and scientific knowledge and to achieve a better, multi-disciplinary harmonisation of the different scientific approaches. After intensive discussions the participants of this workshop formulated the following scientific recommendations for radiation dose reconstruction.

Body Burden↗
PubMed1994

Transferable clastogenic activity in plasma from persons exposed as salvage personnel of the Chernobyl reactor.

Clastogenic factors were first described in the plasma of people who had been accidentally or therapeutically irradiated. They were found also in A-bomb survivors, where they persisted for many years after the irradiation. The present study searched for these factors in the plasma of 32 civil workers from Armenia, who had been engaged as "liquidators" around the Chernobyl atomic power station in 1986. It also included 15 liquidators who had emigrated from the ex-Soviet Union to Israel. Reference plasma samples were obtained from 41 blood donors from the Armenian Blood Center in Yerevan. The samples were tested for their clastogenic activity in blood cultures from healthy donors. The majority of results from the liquidators exceeded those from the unexposed reference samples. The samples from the first Armenian group, with the higher average irradiation dose (0.6 +/- 0.6 Gy), were more clastogenic than those from the second group exposed to 0.2 +/- 0.2 Gy. The number of aberrations in the test cultures was 17.9 +/- 2.9% and 10.5 +/- 3.8% respectively, compared to 5.7 +/- 3.2% in the cultures exposed to the reference ultrafiltrates from Armenian blood donors. The samples from the Israeli liquidators also induced significantly increased aberration rates (14.0 +/- 3.9% aberrant cells). The clastogenic activity was regularly inhibited by superoxide dismutase, indicating that the chromosome-damaging effects of radiation-induced clastogenic factors are exerted via the intermediation of superoxide radicals, as is known for clastogenic factors of different origin.

Accidents↗
PubMed1991

The "post-Chernobyl" childhood leukemia study (ECLIS Study).

Numerous European cancer registries are working together to evaluate the current trends in the incidence of childhood leukemias after the Chernobyl accident. The study is coordinated by the International Agency for Research on Cancer. The primary objective is to establish whether the accident has resulted in an increase in the number of cases. The results will also allow an evaluation of the clusters which could be reported. According to the provisional estimations, the accident could lead to an increase of an average of 0.8% of the frequency of new cases in the European regions covered by the study. For the whole of Switzerland, this increase would correspond to 0.5 supplementary cases per year.

Accidents↗
PubMed1987

[Increased levels of cesium-137 and cesium-134 in 34 mushroom species following the reactor accident at Chernobyl].

From September to December of 1986, 85 samples of 34 species of wild mushrooms were collected, mostly in northern Baden and occasionally in neighboring areas. Cs-137, Cs-134, and the natural nuclide K-40 were determined by gamma-spectrometry. Samples from the Rhine Valley and the Kraichgau were generally much less contaminated than those from the Black Forest. With one exception, their radiocesium levels were below the Common Market limit of 600 Bq/kg. The exception was a sample of Laccaria amethystina with 1710 Bq/kg Cs-137 and 766 Bq/kg Cs-134. Relatively high levels were also found in Xerocomus badius, X. chrysenteron and Cantharellus tubaeformis. The hymenophore contained higher concentrations of radiocesium than the other parts of the body of the fruit. No correlation between the concentration of K-40 and that of the Cs nuclides was found. The ratio of Cs-137:Cs-134 was usually below 3 but reached the value of 11.8 in Piptoporus betulinus growing on birch wood. In this case, the substrate must have contained more radiocesium from the time before the Chernobyl reactor accident than from the time thereafter.

Accidents↗
PubMedDate not supplied

Electroencephalographic correlates of neurological disturbances at remote periods of the effect of ionizing radiation (sequelae of the Chernobyl' NPP accident).

The psychoneurological status of 40 participants (all men aged 25-45 years, official dose 15-51 rem) in the liquidation of the consequences of the accident at the Chernobyl Nuclear Power Plant in 1986-1987 was investigated; EEG mapping and three-dimensional localization of the sources of epileptic activity as compared with the data of healthy individuals (20 individuals) was carried out. Vegetative-vascular symptomatology was identified in the neurological status of all the patients; disseminated organic neurological symptomatology and endocrine disturbances were additionally identified in some of the patients. There were paroxysmal attacks periodically in the overwhelming majority (68%) of the patients; this correlated with the presence in the EEG of epileptic forms of activity. The patients were divided into two groups on the basis of the character of the EEG. Patients in whom slow alpha waves and waves of the theta range with a "focus" in the central-frontal regions of the cortex were recorded were included in group I (25 individuals). Analysis of the localization of the sources of epileptic activity revealed placement at the midline level in them with marked compactness and displacement of the focus to the right hemisphere. In the patients of group II (15 individuals), slow waves of frontal localization and diffuse beta waves predominated in the EEG in the presence of a reduction in the level of biopotentials. The localization of equivalents of epileptic activity was more diffuse in character and was at the basal level, with a greater representation of the sources of epileptic activity in the left hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Electrophysiological characterization of the functional state of the brain in mental disturbances in workers involved in the clean-up following the Chernobyl atomic energy station accident.

Studies were carried out on 150 workers with mental disturbances, who had been involved in the clean-up of the Chernobyl atomic energy station accident. Visual and computer analyses of EEG traces from 43 workers were compared with traces from 17 healthy subjects, and the comparison revealed that the most common features in workers were disorganization of the alpha-rhythm and strengthening of beta-1-activity in the sensorimotor cortex. In neurosis-like syndromes (13 patients), there was a significant increase in the power of the alpha-rhythm in the anterior parts of the cortex; in psycho-organic states, power as significantly reduced (especially in the left hemisphere). Contributing to the greater proportion of flat EEG traces in patients with psycho-organic syndromes as compared with other groups of patients. Most patients among the clean-up workers had increased assimilation of flashing light rhythms and weakening of non-specific and skin galvanic responses to a light stimulus. It was concluded that systemic CNS changes occurred in patients from the clean-up worker groups, especially in those with psycho-organic syndrome.

Adult↗
PubMed1987

Radiation doses in Europe after the Chernobyl accident.

In the course of the reactor accident at Chernobyl in 1986, large amounts of radioactive materials were released and spread over all of Europe and the rest of the world. A comprehensive analysis of the resulting radiation doses is still in progress through the United Nations Scientific Committee on the Effects of Atomic Radiations. This review lists the most significant nuclides involved and the most significant pathways of exposure. Preliminary estimates of radiation doses made by various organisations are presented. Particular emphasis is given to the collective effective dose equivalent which is important for the assessment of the possible future incidence of leukemia and cancer from the accident. This quantity amounted to about 200,000 mansievert for Europe outside of the Soviet Union, and about twice as much for the European part of the Soviet Union, for the first 50 years after the accident. The uncertainty in these estimates should be less than a factor of three up or down. According to the hypothesis of a linear dose-effect relationship this dose could be calculated to result in 6000 extra cases of cancer and hereditary disease, 4000 of which would be fatal, during 100 years in Europe outside the Soviet Union.

Accidents↗
PubMed1996

Chernobyl radioactivity on the Black Sea coast of Turkey.

After the Chernobyl reactor accident, Eastern Black Sea coast was one of the heavily contaminated regions of Turkey. Clouds loaded with radioactive isotopes arrived the region on May 1986 and emptied their contents with the heavy rains that are frequently seen in the region. In order to asses the current level of contamination, several different samples, moss, lichen, litter, surface soil and soil cores were collected on August 1994. Samples were brought to the laboratory and their moisture, pH and organic matter contents were determined. Gamma-ray spectra of the samples were collected with a HpGe detector. (137)Cs was the major isotope observed. Activity of most litter samples were below 1000 Bq/kg, while most of the moss samples had activities below 5000 Bq/kg, there were a few with higher (137)Cs activities. Surface soil samples generally had activities less than 2000 Bq/kg and depth profiles of cesium activities in the soil cores showed regional variations.

Journal Article↗
PubMed2000

Thyroid cancer in children of Ukraine after the Chernobyl accident.

The results of treatment of 330 children (< 14 years) and adolescents (15-18 years) with thyroid cancer who were operated on at the Institute of Endocrinology after the Chernobyl accident in 1986 were analyzed. The number of young patients increased after 1986 (1981-1985, 9 cases; 1986-1990, 37 cases; 1991-1995, 177 cases; 1996-1998, 116 cases). Most of these children and adolescents were younger than 8 years at the time of the accident (84.2%). More than half of the children (58.1%) lived in areas receiving the highest radiation exposure. These thyroid cancers developed after a short latent period, were more aggressive at presentation, and expressed regional (57.3%) or distant (14.5%) metastasis. Solid papillary cancers were present in 93.1%. Coexisting thyroid conditions were common (thyroid hyperplasia, 25.1%; nodular goiter, 18.8%; chronic thyroiditis, 10.2%). Most patients were treated by total thyroidectomy with intraoperative visualization of recurrent laryngeal nerves and parathyroid glands. When lymph node metastases were identified, a modified neck dissection was performed. Such operations were done in 277 (84.1%) patients. Postoperatively, the patients were treated with radioiodine and thyroid-stimulating hormone suppressive therapy. Postoperative complications included recurrent nerve palsy in 12.3% and permanent hypoparathyroidism in 6%. Operations for local recurrence of cancer were performed in 2.8% cases and for regional metastasis in 4%. The general mortality was 1. 8%. We anticipate that there will be more patients with thyroid cancer during the next few years. Therefore this high risk population for thyroid cancer must be carefully monitored and evaluated during the next several decades.

Adolescent↗
PubMed2001

Childhood leukemia in Belarus before and after the Chernobyl accident: continued follow-up.

Earlier assessments led to the conclusion that due to the added radiation after the Chernobyl accident, childhood leukemia in Belarus was not recognisably increased in the years 1987-1994 compared to the years 1982-1986, i.e. the period before the accident. The present paper gives the data of the continued follow-up (1995-1998) which was conducted by the Institute of Haematology and Blood Transfusion, Minsk. In line with the earlier observations no increase has been identified. The incidence rates have been compared to the data of the newly established Belarussian Childhood Cancer Registry and a tentative explanation is given for apparent differences between the rates from our follow-up and the data reported earlier by the Belarussian Childhood Cancer Registry.

Adolescent↗
PubMed2002

Thyroid cancer incidence among liquidators of the Chernobyl accident. Absence of dependence of radiation risks on external radiation dose.

The increase of thyroid cancer incidence rate among children living in the Chernobyl contaminated territories of Belarus, Russia and Ukraine has widely been accepted. Our current work deals with thyroid cancer incidence in the cohort of liquidators (99024 persons) living in 6 regions of Russia: North-West, Volgo-Vyatsky, Central-Chernozemny, Povolzhsky, North-Caucasus and Urals. In the period 1986-1998, a total of 58 thyroid cancer cases were detected in this cohort. We found a statistically significant increase of the thyroid cancer incidence rate in liquidators as compared to the baseline (male population of Russia) level (SIR=4.33, 95% CI: 3.29; 5.60). It was demonstrated that there is no dependence of incidence rates due to external radiation exposure (ERR/Gy=-2.23, 95% CI: -4.67; 0.22).

Adolescent↗
PubMed2002

External exposure of the population living in areas of Russia contaminated due to the Chernobyl accident.

An updated version of external dose modeling is presented with reference to the population in Russian areas contaminated due to the Chernobyl accident. An earlier version has been modified by applying a study time interval with a starting point immediately after radionuclide deposition (rather than 4 years after the accident as applied earlier) and by introducing an estimate of individual dose distributions. New input data to the model are the nuclide-specific composition of the deposit, additional data about migration of caesium in soil, time dependence of location factors and uncertainty distributions of all input parameters. Model results (i.e. effective dose-rates and accumulated effective doses) from external exposure for the rural and urban populations in contaminated areas of Russia during 100 years after the accident are presented. Radionuclide contributions to the dose during various time intervals after the accident have been estimated. The model has been validated by measurements of absorbed dose-rate in air during the first 30 days after the accident and by TLD measurements of individual external doses among inhabitants of contaminated rural settlements in the year 1993. Both the measurements and model show that the geometric mean of individual external doses is about 10% lower than the arithmetic mean and the upper bound of the 95% confidence range is larger by a factor of about 2.

Adolescent↗
PubMed2000

Current development of the human and environmental contamination in the Bryansk-Gomel Spot after the Chernobyl accident.

Up to 1991, it was assumed that after the Chernobyl accident in 1986 the time development of radioactive contamination with regard to environment, foodstuff, and man would decrease due to migration processes in the soil, radioactive decay, and protective measures. This assumption was confirmed by all measurements in the first few years after the accident. Since 1991, however, a change in this development has been observed, as many measurements show stagnation or in some cases even an increase of foodstuff and human contamination. If normalised to an average local ground contamination, only a few groups of foodstuffs (e.g., potatoes) show a slight decrease in radioactivity. In this paper, the time development of radioactive contamination in the Bryansk-Gomel Spot on the basis of measurements since 1991 is presented. The consequences for long-term dose assessment are discussed.

Food Contamination, Radioactive↗
PubMed2000

Analysis of thyroid cancer data from the Ukraine after 'Chernobyl' using a two-mutation carcinogenesis model.

The thyroid cancer data of children in the northern regions of the Ukraine after the reactor accident at Chernobyl were combined with thyroid dose measurements in the same regions and analysed using a two-mutation carcinogenesis model. The best fit was obtained for radiation acting as an initiating agent, i.e. on the first mutation of the model. The observed relatively high increase of thyroid cancer incidence after 1990 in children exposed to radiation released after the reactor accident could be ascribed to the high thyroid doses and the relatively low background thyroid cancer incidence in children. The maximum annual incidence is predicted to occur fairly soon after the reactor accident, i.e. about 10 years. For adults, the predicted relative increase of annual thyroid cancers is much lower than for children younger than 20 years. The modelling results are used to derive risk estimates for radiation-induced thyroid cancer. These risk estimates are dependent on age at exposure, follow-up time and the background thyroid cancer incidence. The calculated excess absolute risk for a population of all ages is about one-third of that currently used by ICRP, but for children the calculated absolute risks are about a factor of 3 higher than derived in other epidemiological studies. The model results indicate that the excess absolute radiation risk per unit dose for children is about the same as or a little lower than that for adults.

Adolescent↗