Analysis of EPR and FISH studies of radiation doses in persons who lived in the upper reaches of the Techa River.

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949-1956 resulted in significant doses to about 30,000 persons who lived in downstream settlements. The residents were exposed to internal and external radiation. Two methods for reconstruction of the external dose are considered in this paper, electron paramagnetic resonance (EPR) measurements of teeth, and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. The main issue in the application of the EPR and FISH methods for reconstruction of the external dose for the Techa Riverside residents was strontium radioisotopes incorporated in teeth and bones that act as a source of confounding local exposures. In order to estimate and subtract doses from incorporated (89,90)Sr, the EPR and FISH assays were supported by measurements of (90)Sr-body burdens and estimates of (90)Sr concentrations in dental tissues by the luminescence method. The resulting dose estimates derived from EPR to FISH measurements for residents of the upper Techa River were found to be consistent: The mean values vary from 510 to 550 mGy for the villages located close to the site of radioactive release to 130-160 mGy for the more distant villages. The upper bound of individual estimates for both methods is equal to 2.2-2.3 Gy. The EPR- and FISH-based dose estimates were compared with the doses calculated for the donors using the most recent Techa River Dosimetry System (TRDS). The TRDS external dose assessments are based on the data on contamination of the Techa River floodplain, simulation of air kerma above the contaminated soil, age-dependent lifestyles and individual residence histories. For correct comparison, TRDS-based doses were calculated from two sources: external exposure from the contaminated environment and internal exposure from (137)Cs incorporated in donors' soft tissues. It is shown here that the TRDS-based absorbed doses in tooth enamel and muscle are in agreement with EPR- and FISH-based estimates within uncertainty bounds. Basically, this agreement between the estimates has confirmed the validity of external doses calculated with the TRDS.

Age and gender specific biokinetic model for strontium in humans.

A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitations for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on (90)Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has a similar structure to the ICRP model for the alkaline earth elements. The following parameters were mainly re-evaluated: gastrointestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0-80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general populations exposed to ingested strontium radioisotopes.

EPR-based uncertainty validation of the calculated external doses for population exposed in the urals region.

Tooth enamel Electron Paramagnetic Resonance (EPR) spectroscopy was used as a method for external dosimetry in the territories contaminated in the 1950s by PA 'Mayak' (Urals region) to validate the mean dose estimates predicted by the Techa River Dosimetry System (TRDS). The purpose of this study is to validate the uncertainties of TRDS doses. Ninety percent confidence intervals (90% confidence interval, CI) of dose estimated with both methods were compared for 220 people. All data were grouped according to the width of 90%CI, viz.: (1) 90%CI of EPR-based dose ≤  90%CI of TRDS prediction (38 cases); (2) 90%CI of EPR-based dose >  90%CI of TRDS prediction (182 cases). About 91% of 90%CIs overlap. In group 1, 100% cases overlap. In group 2, 80% of the cases were non-contradictive (the calculated 90%CI is completely within the measured one). Interval comparison of doses predicted retrospectively and estimated based on individual measurements are non-contradictory and demonstrate a good agreement.

Luminescence dosimetry for evaluation of the external exposure in Metlino, upper Techa River valley, Southern Urals, Russia: Analysis of new results.

Luminescence dosimetry was applied in the former settlement of Metlino, Southern Urals, Russia as part of a full-scale study to validate the Techa River Dosimetry System (TRDS) 2016 for the upper Techa River region. The village, which was evacuated in 1956, was located 7 km downstream of the release point of liquid radioactive waste by the Mayak plutonium facility. Several brick samples were taken from north-eastern and south-eastern walls of the granary, facing the former Techa river shoreline and floodplain. Samples were all taken at the same height and measured at different depths into the brick. For the majority of brick samples, good Optically Stimulated Luminescence properties of the quartz grains were observed. In some cases, however, strong levels of sensitization and/or signal recuperation were encountered which necessitated adjustment in the measurement protocols. Anthropogenic doses in bricks varied from 1.5 to 6.6 Gy and the horizontal profiles along both walls showed significant variation, which is explained on a qualitative basis. A dose depth profile is observed for selected samples, which is different from the dose depth profile measured and simulated for samples from the north-western wall of the granary in previous studies. This is qualitatively explained by the differences in source configuration.

Reconstruction of the contamination of the Techa River in 1949-1951 as a result of releases from the "Mayak" Production Association.

More accurate reconstruction of the radioactive contamination of the Techa River system in 1949-1951 has been made on the basis of refined data on the amounts and the rate of discharge of radionuclides into the Techa River from the Mayak Production Association; this has led to the development of a modified Techa River model that describes the transport of radionuclides through the up-river ponds and along the Techa River and deposition of radionuclides in the river-bottom sediments and flooded areas. The refined Techa River source-term data define more precisely the time-dependent rates of release and radionuclide composition of the releases that occurred during 1949-1951. The Techa River model takes into account the time-dependent characteristics of the releases and considers (a) the transport of radionuclides adsorbed on solid particles originally contained in the discharges or originating in the up-river ponds as a result of stirring up of contaminated bottom sediments and (b) the transport of radionuclides in soluble form. The output of the Techa River model provides concentrations of all source-term radionuclides in the river water, bottom sediments, and floodplain soils at different distances from the site of radioactive releases for the period of major contamination in 1950-1951. The outputs of the model show good agreement with historical measurements of water and sediment contamination. In addition, the river-model output for (90)Sr concentration in the river water is harmonized with retrospective estimates derived from the measurements of (90)Sr in the residents of the Techa Riverside villages. Modeled contamination of the floodplain soils by (137)Cs is shown to be in agreement with the values reconstructed from late measurements of this radionuclide. Reconstructed estimates of the Techa River contamination are being used for the quantification of internal and external doses received by residents of the Techa Riverside communities.

Trabecula: A Random Generator of Computational Phantoms for Bone Marrow Dosimetry.

This study was motivated by the efforts to evaluate radiation risk for leukemia incidence in the Techa River cohort, where the main bone marrow dose contributors were Sr (bone-seeking beta emitters). Energy deposition in bone marrow targets was evaluated by simulating radiation particle transport using computational phantoms. The present paper describes the computer program Trabecula implementing an algorithm for parametric generation of computational phantoms, which serve as the basis for calculating bone marrow doses. Trabecula is a user-friendly tool that automatically converts analytical models into voxelized representations that are directly compatible as input to Monte Carlo N Particle code.

APPLICATION OF EPR TOOTH DOSIMETRY FOR VALIDATION OF THE CALCULATED EXTERNAL DOSES: EXPERIENCE IN DOSIMETRY FOR THE TECHA RIVER COHORT.

This study applies EPR tooth dosimetry for validation of external doses calculated with the TRDS-2016. EPR-based external dose in tooth enamel is calculated by subtraction of the contributions of natural and anthropogenic sources from the exposure of interest. These subtracted terms may contribute substantially to the overall uncertainty of the EPR-derived external dose. The validation method strongly depends on the uncertainties. The current study combines the results of a number of previous papers to propagate the uncertainty of EPR-derived external doses. It is concluded that the overall uncertainties of D ≥ 500 mGy are comparable with measurement uncertainties (≤30%); the overall uncertainties of D < 500 mGy become higher as the EPR-dose decreases because they are strongly effected by all other factors of influence. More than 70% of investigated individuals were exposed externally to doses <100 mGy with uncertainties >100%. Therefore, the validation task can be solved only based on statistical approaches. The validation of the TRDS-2016 predictions demonstrates good convergence of group-averages with EPR-based doses. The method for validation of the uncertainty of TRDS-2016 predictions should be also designed based on statistical approaches.

Enhancements in the Techa River Dosimetry System: TRDS-2016D Code for Reconstruction of Deterministic Estimates of Dose From Environmental Exposures.

Waterborne releases to the Techa River from the Mayak plutonium facility in Russia during 1949-1956 resulted in significant doses to persons living downstream. The dosimetry system Techa River Dosimetry System-2016D has been developed, which provides individual doses of external and internal exposure for the members of the Techa River cohort and other persons who were exposed to releases of radioactive material to the Southern Urals. The results of computation of individual doses absorbed in red bone marrow and extraskeletal tissues for the Techa River cohort members (29,647 persons) are presented, which are based on residence histories on the contaminated Techa River and the East Urals Radioactive Trace, which was formed in 1957 as a result of the Kyshtym Accident. Available Sr body-burden measurements and available information on individual household locations have been used for refinement of individual dose estimates. Techa River Dosimetry System-2016D-based dose estimates will be used for verification of risk of low-dose-rate effects of ionizing radiation in the Techa River cohort.

Application of real-time and multiplex polymerase chain reaction assays to study leaf blotch epidemics in barley.

ABSTRACT Leaf blotch, caused by Rhynchosporium secalis, was studied in a range of winter barley cultivars using a combination of traditional plant pathological techniques and newly developed multiplex and real-time polymerase chain reaction (PCR) assays. Using PCR, symptomless leaf blotch colonization was shown to occur throughout the growing season in the resistant winter barley cv. Leonie. The dynamics of colonization throughout the growing season were similar in both Leonie and Vertige, a susceptible cultivar. However, pathogen DNA levels were approximately 10-fold higher in the susceptible cultivar, which expressed symptoms throughout the growing season. Visual assessments and PCR also were used to determine levels of R. secalis colonization and infection in samples from a field experiment used to test a range of winter barley cultivars with different levels of leaf blotch resistance. The correlation between the PCR and visual assessment data was better at higher infection levels (R(2) = 0.81 for leaf samples with >0.3% disease). Although resistance ratings did not correlate well with levels of disease for all cultivars tested, low levels of infection were observed in the cultivar with the highest resistance rating and high levels of infection in the cultivar with the lowest resistance rating.

Radioactive waste management and environmental contamination issues at the Chernobyl site.

The destruction of the Unit 4 reactor at the Chernobyl Nuclear Power Plant resulted in the generation of radioactive contamination and radioactive waste at the site and in the surrounding area (referred to as the Exclusion Zone). In the course of remediation activities, large volumes of radioactive waste were generated and placed in temporary near-surface waste storage and disposal facilities. Trench and landfill type facilities were created from 1986-1987 in the Chernobyl Exclusion Zone at distances 0.5-15 km from the nuclear power plant site. This large number of facilities was established without proper design documentation, engineered barriers, or hydrogeological investigations and they do not meet contemporary waste-safety requirements. Immediately following the accident, a Shelter was constructed over the destroyed reactor; in addition to uncertainties in stability at the time of its construction, structural elements of the Shelter have degraded as a result of corrosion. The main potential hazard of the Shelter is a possible collapse of its top structures and release of radioactive dust into the environment. A New Safe Confinement (NSC) with a 100 y service life is planned to be built as a cover over the existing Shelter as a longer-term solution. The construction of the NSC will enable the dismantlement of the current Shelter, removal of highly radioactive, fuel-containing materials from Unit 4, and eventual decommissioning of the damaged reactor. More radioactive waste will be generated during NSC construction, possible Shelter dismantling, removal of fuel-containing materials, and decommissioning of Unit 4. The future development of the Exclusion Zone depends on the future strategy for converting Unit 4 into an ecologically safe system, i.e., the development of the NSC, the dismantlement of the current Shelter, removal of fuel-containing material, and eventual decommissioning of the accident site. To date, a broadly accepted strategy for radioactive waste management at the reactor site and in the Exclusion Zone, and especially for high level and long-lived waste, has not been developed.

An approach to reduction of uncertainties in internal doses reconstructed for the Techa River population.

A methodology was developed for reduction of uncertainties in estimates of internal dose for residents of the Techa Riverside communities, who were exposed as a result of releases of radionuclides from the Mayak plutonium production facility in 1949-56. The 'Techa River Dosimetry System' (TRDS) was specifically elaborated for reconstruction of doses. A preliminary analysis of uncertainty for doses estimated using the current version of the TRDS showed large ranges in the uncertainty of internal absorbed dose and led to suggestions of methods to reduce uncertainties. The new methodological approaches described in this paper will allow for significant reduction of uncertainties of 90Sr-dose. The major sources of reduction are: making use of individual measured values of 90Sr and through development of a Household Registry to associate unmeasured persons with measured persons living in the same household(s).

THE MAYAK WORKER DOSIMETRY SYSTEM (MWDS-2013): AN INTRODUCTION TO THE DOCUMENTATION.

The reconstruction of radiation doses to Mayak Production Association workers in central Russia supports radiation epidemiological studies for the U.S.-Russian Joint Coordinating Committee on Radiation Effects Research. The most recent version of the dosimetry was performed with the Mayak Worker Dosimetry System-2013. This introduction outlines the logic and general content of the series of articles presented in this issue of Radiation Protection Dosimetry. The articles summarize the models, describe the basis for most of the key decisions made in developing the models and present an overview of the results.

THE MAYAK WORKER DOSIMETRY SYSTEM (MWDS-2013) FOR INTERNALLY DEPOSITED PLUTONIUM: AN OVERVIEW.

The Mayak Worker Dosimetry System (MWDS-2013) is a system for interpreting measurement data from Mayak workers from both internal and external sources. This paper is concerned with the calculation of annual organ doses for Mayak workers exposed to plutonium aerosols, where the measurement data consists mainly of activity of plutonium in urine samples. The system utilises the latest biokinetic and dosimetric models, and unlike its predecessors, takes explicit account of uncertainties in both the measurement data and model parameters. The aim of this paper is to describe the complete MWDS-2013 system (including model parameter values and their uncertainties) and the methodology used (including all the relevant equations) and the assumptions made. Where necessary, Supplementary papers which justify specific assumptions are cited.

Development of an improved dose reconstruction system for the Techa River population affected by the operation of the Mayak Production Association.

The Techa River Dosimetry System (TRDS) has been developed to provide estimates of dose received by approximately 30,000 members of the Extended Techa River Cohort (ETRC). Members of the ETRC were exposed beginning in 1949 to significant levels of external and internal (mainly from (90)Sr) dose but at low to moderate dose rates. Members of this cohort are being studied in an effort to test the hypothesis that exposure at low to moderate dose rates has the same ability to produce stochastic health effects as exposure at high dose rates. The current version of the TRDS is known as TRDS-2000 and is the subject of this paper. The estimated doses from (90)Sr are supported strongly by approximately 30,000 measurements made with a tooth beta-particle counter, measurements of bones collected at autopsy, and approximately 38,000 measurements made with a special whole-body counter that detects the bremsstrahlung from (90)Y. The median doses to the red bone marrow and the bone surface are 0.21 and 0.37 Gy, respectively. The maximum doses to the red bone marrow and bone surface are 2.0 and 5.2 Gy, respectively. Distributions of dose to other organs are provided and are lower than the values given above. Directions for future work are discussed.

Model testing using data on 131I released from Hanford.

The Hanford test scenario described an accidental release of 131I to the environment from the Hanford Purex Chemical Separations Plant in September 1963. Based on monitoring data collected after the release, this scenario was used by the Dose Reconstruction Working Group of BIOMASS to test models typically used in dose reconstructions. The primary exposure pathway in terms of contribution to human doses was ingestion of contaminated milk and vegetables. Predicted mean doses to the thyroid of reference individuals from ingestion of 131I ranged from 0.0001 to 0.8 mSv. For one location, predicted doses to the thyroids of two children with high milk consumption ranged from 0.006 to 2 mSv. The predicted deposition at any given location varied among participants by a factor of 5-80. The exercise provided an opportunity for comparison of assessment methods and conceptual approaches, testing model predictions against measurements, and identifying the most important contributors to uncertainty in the assessment result. Key factors affecting predictions included the approach to handling incomplete data, interpretation of input information, selection of parameter values, adjustment of models for site-specific conditions, and treatment of uncertainties.

The neurotensin antagonist SR 48692 fails to modify the behavioural responses to a dopamine D1 receptor agonist in the rat.

The effects of the neurotensin antagonist SR 48692 on the behavioural responses to the dopamine D1 receptor agonist SKF 38393 were investigated in the rat. SKF 38393 (5 mg/kg s.c.) elicited vacuous chewing movements (VCMs) and grooming, which were unaffected by SR 48692 (50 micrograms/kg i.p.). The dopamine D2 receptor antagonist raclopride (0.5 mg/kg s.c.) elicited a small increase in VCMs in animals treated with SR 48692 and attenuated grooming induced by SKF 38393. These effects were not otherwise modified by SR 48692. We conclude that VCMs induced by acute administration of a dopamine D1 receptor agonist are unlikely to be dependent upon enhanced release of neurotensin in the striatum or its projections. This is contrast to the vacuous chewing response which emerges following chronic administration of neuroleptics, which is attenuated by neurotensin receptor antagonist. Thus, inasmuch as chronic neuroleptic-induced VCMs in the rat may be analogous to tardive dyskinesia in humans, the responses induced by acute administration of a D1 agonist to the rat cannot be used as a model of this disorder. Furthermore, the behavioural effects of chronic neuroleptic administration reflect more than a simple shift in the balance of D1 versus D2 receptor stimulation.

Evaluation of age and gender dependences of the rate of strontium elimination 25-45 years after intake: analysis of data from residents living along the Techa river.

The Mayak Production Association released large amounts of 90Sr into the Techa River with peak amounts in 1950-1951. Residents near the Techa River ingested an average of approximately 3,000 kBq of 90Sr. The affected people have been followed by scientists at the Urals Research Center for Radiation Medicine. The whole-body content of 90Sr of approximately 15,000 individuals has been measured over a period of 24 years (1974-1997) using a special whole-body counter. This report evaluates the gender and age dependences of individual rates of strontium elimination. Data on persons who had been measured 12 or more times were selected for study. There were 108 men and 81 women older than 30 years who met this criterion. Individual measurement results were fitted to an exponential function and grouped mean averages of the rate of strontium elimination as a function of age for each sex were derived. For men, a significant increase (from 2.8% year(-1) to 3.2% year(-1)) in the rate of strontium elimination after age 55 years is seen. For women, the increase in the rate of elimination was significant at age 45 and reached 5.8% year(-1) after the age of 60. The results may be used to develop a gender- and age-dependent model of strontium metabolism.

DNA restriction endonuclease cleavage pattern and protein antigen profile of Ehrlichia risticii.

Molecular characterization of Ehrlichia risticii, the etiological agent of Potomac horse fever, was performed. Restriction endonuclease cleavage of E. risticii DNA generated distinct patterns by different enzymes. The DNA cleavage patterns of E. risticii isolates obtained from different geographic regions were similar. Protein analysis identified thirty-five distinct proteins with molecular weights ranging from 160 to 16 kilodalton (kDa). Antigenic analysis by radioimmunoprecipitation using 125I surface labeled E. risticii and by Western blotting determined the presence of eighteen antigens (160, 110, 86, 84, 81, 70, 55, 51, 49, 44, 41, 36, 33, 31, 28, 24, 22 and 16 kDa) of which nine (110, 86, 70, 55, 51, 49, 44, 33, and 28 kDa) were major antigens. Fourteen of these antigens, which included the major antigens, were apparent surface components. There were no heat-modifiable proteins but lipopolysaccharide components of 245 and 14 kDa, resistant to proteinase K and of non-antigenic character, were detected in the organism.

Acquired immune deficiency syndrome presenting as oral pharyngeal and cutaneous Kaposi's sarcoma.

A 25-year-old black male homosexual with AIDS presented with Kaposi's sarcoma of the tongue, palate and skin. The definition, epidemiology, diagnosis, treatment and prognosis of AIDS are discussed. The role of the otolaryngologist-head and neck surgeon in diagnosing this disease is outlined.

Neuroendocrine and stress hormone changes during mirthful laughter.

Positive emotional activities have been suggested as modifiers of neuroendocrine hormones involved in the classical stress response. To detect changes in these components during a mirthful laughter experience, the authors studied 10 healthy male subjects. Five experimental subjects viewed a 60 minute humor video and five control subjects did not. Serial blood samples were measured for corticotropin (ACTH), cortisol, beta-endorphin, 3,4-dihydrophenylacetic acid (dopac)--the major serum neuronal catabolite of dopamine, epinephrine, norepinephrine, growth hormone, and prolactin. Repeated measures analysis of variance showed that cortisol and dopac in the experimental group decreased more rapidly from baseline than the control group (p = 0.011, p = 0.025, respectively). Epinephrine levels in the experimental group were significantly lower than the control at all time points (p = 0.017). Growth hormone levels in the experimental group significantly increased during baseline (p = 0.027) and then decreased with laughter intervention (p less than 0.0005), whereas, the controls did not change over time (p = 0.787). ACTH, beta-endorphin, prolactin, and norepinephrine levels did not significantly increase. The mirthful laughter experience appears to reduce serum levels of cortisol, dopac, epinephrine, and growth hormone. These biochemical changes have implications for the reversal of the neuroendocrine and classical stress hormone response.