Health risks from radioactive particles on Cumbrian beaches near the Sellafield nuclear site.

A monitoring programme, in place since 2006, continues to recover radioactive particles (<2 mm diameter) and larger objects from the beaches of West Cumbria. The potential risks to members of the public using the beaches are mainly related to prolonged skin contact with or the inadvertent ingestion of small particles. Most particles are classified as either 'beta-rich' or 'alpha-rich' and are detected as a result of their caesium-137 or americium-241 content. Beta-rich particles generally also contain strontium-90, with90Sr:137Cs ratios of up to about 1:1, but typically <0.1:1. Alpha-rich particles contain plutonium isotopes, with Pu:241Amαratios usually around 0.5-0.6:1. 'Beta-rich' particles have the greatest potential to cause localised skin damage if held in stationary contact with the skin for prolonged periods. However, it is concluded that only particles of >106Bq of137Cs, with high90Sr:137Cs ratios, would pose a significant risk of causing acute skin ulceration. No particles of this level of activity have been found. Inadvertent ingestion of a particle will result in the absorption to blood of a small proportion of the radionuclide content of the particle. The subsequent retention of radionuclides in body organs and tissues presents a potential risk of the development of cancer. For 'beta-rich' particles with typical activities (mean 2 × 104Bq137Cs, Sr:Cs ratio of 0.1:1), the estimated committed effective doses are about 30µSv for adults and about 40µSv for 1 year old infants, with lower values for 'alpha-rich' particles of typical activities. The corresponding estimates of lifetime cancer incidence following ingestion for both particle types are of the order of 10-6for adults and up to 10-5for infants. These estimates are subject to substantial uncertainties but provide an indication of the low risks to members of the public.

Four-decade follow-up of a plutonium-contaminated puncture wound treated with Ca-DTPA.

Contaminated wounds are a common route of internal deposition of radionuclides for nuclear and radiation workers. They may result in significant doses to radiosensitive organs and tissues in an exposed individual's body. The United States Transuranium and Uranium Registries' whole-body donor (Case 0303) accidentally punctured his finger on equipment contaminated with plutonium nitrate. The wound was surgically excised and medically treated with intravenous injections of Ca-DTPA. A total of 16 g Ca-DTPA was administered in 18 treatments during the 2 months following the accident. Ninety-three urine samples were collected and analysed over 14 years following the accident. An estimated239Pu activity of 73.7 Bq was excreted during Ca-DTPA treatment. Post-mortem radiochemical analysis of autopsy tissues indicated that 40 years post-accident 21.6 ± 0.2 Bq of239Pu was retained in the skeleton, 12.2 ± 0.3 Bq in the liver, and 3.7 ± 0.1 Bq in other soft tissues; 1.35 ± 0.02 Bq of239Pu was measured in tissue samples from the wound site. To estimate the plutonium intake, late urine measurements, which were unaffected by chelation, and post-mortem radiochemical analysis results were evaluated using the IMBA Professional Plus software. The application of the National Council on Radiation Protection and Measurements wound model with an assumption of intake material as a predominantly strongly retained soluble plutonium compound with a small insoluble fraction adequately described the data (p= 0.46). The effective intake was estimated to be 50.2 Bq of plutonium nitrate and 1.5 Bq of the fragment. The prompt medical intervention with contaminated tissue excision and subsequent Ca-DTPA decorporation therapy reduced239Pu activity available for uptake and long-term retention in this individual's systemic organs by a factor of 38.

Radioecological consequences of radioactive releases due to weapons-grade plutonium production at the 'Mayak' facility in the Russian Federation.

The process of nuclear weapons production from 1949 to 1987 was accompanied by the generation of a great amount of radioactive waste. Waste processing operations and controls on discharges at this time were not to the same standard as today. Because of this, vast areas of the Urals region of Russia surrounding the Mayak Production Association (MPA) were exposed to routine and accidental radioactive contamination. The greatest contribution to the contamination was gas aerosol emissions from the MPA in the 1950s (total activity 38 PBq, mainly131I), releases of liquid radioactive waste into the Techa River from 1949 to 1956 (total activity 115 PBq, including long-lived90Sr and137Cs) and accidental atmospheric releases as a result of the thermochemical explosion of the storage tank for liquid radioactive waste in 1957 (74 PBq, relatively short-lived radionuclides being the main contributors). Protective measures helped to relieve the pressing problem of population safety in the 1950s and 1960s, but they led to the appearance of new sources of contamination in the territory surrounding the MPA-Lake Karachay (total activity of beta-emitters 4400 PBq) and the Techa Cascade of Reservoirs (TCR; total activity 8 PBq). Owing to natural radioactive decay and rehabilitation measures, the radiation situation in the East Urals Radioactive Trace (EURT) has improved considerably over the years. Economic activity has been partially restored in these territories. Only the most contaminated territory of the East Urals Radioactive Reserve cannot be used for any economic activities up to the present day. Marked non-uniformity of radioactive contamination of the EURT and the Techa River floodplain, as well as radionuclide washout from Lake Karachay and the TCR into the underground waters and the Techa River require on-going radioecological monitoring, management and regulatory supervision.

Chronic Occupational Exposure to Ionizing Radiation Induces Alterations in the Structure and Metabolism of the Heart: A Proteomic Analysis of Human Formalin-Fixed Paraffin-Embedded (FFPE) Cardiac Tissue.

Epidemiological studies on workers employed at the Mayak plutonium enrichment plant have demonstrated an association between external gamma ray exposure and an elevated risk of ischemic heart disease (IHD). In a previous study using fresh-frozen post mortem samples of the cardiac left ventricle of Mayak workers and non-irradiated controls, we observed radiation-induced alterations in the heart proteome, mainly downregulation of mitochondrial and structural proteins. As the control group available at that time was younger than the irradiated group, we could not exclude age as a confounding factor. To address this issue, we have now expanded our study to investigate additional samples using archival formalin-fixed paraffin-embedded (FFPE) tissue. Importantly, the control group studied here is older than the occupationally exposed (>500 mGy) group. Label-free quantitative proteomics analysis showed that proteins involved in the lipid metabolism, sirtuin signaling, mitochondrial function, cytoskeletal organization, and antioxidant defense were the most affected. A histopathological analysis elucidated large foci of fibrotic tissue, myocardial lipomatosis and lymphocytic infiltrations in the irradiated samples. These data highlight the suitability of FFPE material for proteomics analysis. The study confirms the previous results emphasizing the role of adverse metabolic changes in the radiation-associated IHD. Most importantly, it excludes age at the time of death as a confounding factor.

Building a job-exposure matrix for early plutonium workers at the Sellafield nuclear site, United Kingdom.

The potential for adverse health effects from internal exposure to Plutonium has been recognised since its discovery in the 1940s. However, in the absence of specific information, potential risks from Plutonium exposure have always largely been controlled through knowledge of radiation exposure risks in general, much of which comes from external radiation exposures. To try to obtain more direct estimates of potential internal exposure risks, epidemiological studies of Plutonium workers need to be conducted. Such epidemiological analyses require individual Plutonium exposure estimates that are as accurate and unbiased as possible. The UK Sellafield workforce includes one of the world's largest cohorts of Plutonium workers, which constitutes, by some considerable margin, the group of workers most comprehensively monitored for internal exposure to this alpha-particle-emitter. However, for several hundred workers employed at the start of Plutonium work at the facility, during the period from 1952 through to 1963, the historical urinalysis results available cannot provide sufficiently accurate and unbiased exposure assessments needed for use in epidemiological studies. Consequently, these early workers have had to be excluded from epidemiological analyses and this has significantly reduced the power of these studies. A promising quantitative methodology to overcome the issue of missing or deficient exposure data, is to use exposure data from other sources to estimate the average exposure a 'typical worker' would have received, and to collate this information for specific occupations and years. This approach is called a Job-Exposure Matrix (JEM). Work on a pilot study to construct a population-specific quantitative JEM for the early Plutonium workers at Sellafield during 1952-1963, for whom reliable urinalysis results do not exist, has shown the potential for a JEM approach to produce more reliable and useful exposure estimates for epidemiological research.

Risk of Lung Cancer Mortality in Nuclear Workers from Internal Exposure to Alpha Particle-emitting Radionuclides.

BACKGROUND: Carcinogenic risks of internal exposures to alpha-emitters (except radon) are poorly understood. Since exposure to alpha particles-particularly through inhalation-occurs in a range of settings, understanding consequent risks is a public health priority. We aimed to quantify dose-response relationships between lung dose from alpha-emitters and lung cancer in nuclear workers. METHODS: We conducted a case-control study, nested within Belgian, French, and UK cohorts of uranium and plutonium workers. Cases were workers who died from lung cancer; one to three controls were matched to each. Lung doses from alpha-emitters were assessed using bioassay data. We estimated excess odds ratio (OR) of lung cancer per gray (Gy) of lung dose. RESULTS: The study comprised 553 cases and 1,333 controls. Median positive total alpha lung dose was 2.42 mGy (mean: 8.13 mGy; maximum: 316 mGy); for plutonium the median was 1.27 mGy and for uranium 2.17 mGy. Excess OR/Gy (90% confidence interval)-adjusted for external radiation, socioeconomic status, and smoking-was 11 (2.6, 24) for total alpha dose, 50 (17, 106) for plutonium, and 5.3 (-1.9, 18) for uranium. CONCLUSIONS: We found strong evidence for associations between low doses from alpha-emitters and lung cancer risk. The excess OR/Gy was greater for plutonium than uranium, though confidence intervals overlap. Risk estimates were similar to those estimated previously in plutonium workers, and in uranium miners exposed to radon and its progeny. Expressed as risk/equivalent dose in sieverts (Sv), our estimates are somewhat larger than but consistent with those for atomic bomb survivors.See video abstract at, http://links.lww.com/EDE/B232.

Mortality from solid cancers other than lung, liver, and bone in relation to external dose among plutonium and non-plutonium workers in the Mayak Worker Cohort.

Exposure to ionizing radiation has well-documented long-term effects on cancer rates and other health outcomes in humans. While in vitro experimental studies had demonstrated that the nature of some radiation effects depend on both total dose of the radiation and the dose rate (i.e., the pattern of dose distribution over time), the question of whether or not the carcinogenic effect of radiation exposure depends on the dose rate remains unanswered. Another issue of interest concerns whether or not concomitant exposure to external gamma rays and inhaled plutonium aerosols has any effect on the external exposure effects. The analyses of the present paper focus on the risk of solid cancers at sites other than lung, liver, and bone in Mayak workers. Recent findings are reviewed indicating that there is no evidence of plutonium dose response for these cancers in the Mayak worker cohort. Then the evidence for differences in the external dose effects among workers with and without the potential for exposure to alpha particles from inhaled plutonium is examined. It is found that there is no evidence that exposure to plutonium aerosols significantly affects the risk associated with external exposure. While the Mayak external dose risk estimate of an excess relative risk of 0.16 per Gy is somewhat lower than an appropriately normalized risk estimate from the Life Span Study of Japanese atomic bomb survivors, the uncertainties in these estimates preclude concluding that the external dose excess relative risks of this group of solid cancers differ in the two cohorts.

[Deletions in Mitochondrial DNA from the Peripheral Blood of Mayak PA Workers Exposed to Long-Term Ionizing Radiation].

The number of large deletions of mitochondrial DNA in whole peripheral blood of the former Mayak PA workers occupationally exposed to prolonged γ-radiation has been determined in the long term period after irradiation (mean cumulative dose 135.40 ± 22.03 cGy, age range at the time of blood sampling 67-76 years) and compared with the number of deletions in groups of "young" (19-33 years) and "adult" (66-73 years) individuals who had no contact with radiation sources. Samples of the total DNA from the peripheral blood were obtained from the Radiobiological Human Tissue Repository of the Southern Urals Biophysics Institute (Ozyorsk, Chelyabinsk region) and used for carrying out a long-distance PCR. The analysis of the data showed a statistically significant increase in the number of large deletions in the peripheral blood of "adult" donors of the control group as compared with the control group of "young" donors (51.6 and 14.3%, respec- tively). No statistically significant difference in the number of large deletions in the group of former Mayak PA workers occupationally subjected to prolonged exposure to γ-radiation as compared with the control do- nors of similar age was found (53.6 and 43.8% respectively).

[Assessment of the Status of Effector and Regulatory Components of Immune System in Chelyabinsk Region Residents Exposed to Radiation Due to Residence in the Area Contaminated as a Result of the Radiation Accident at Mayak PA and in Their Offspring].

Immune status was studied in the framework of the current work and the results of the analysis of concentration of 26 characteristic parameters of innate and acquired immunity in 140 individuals from 56 trios (fathers, mothers and their Ist generation offspring that were included in 2 groups) are presented. Fathers and mothers of the children under study in the main groip Were exposed due to a long-term residence (from childhood to maturity) in the areas of Chelyabinsk region contaminated as a result of the-accident at Mayak PA (contamination included long-lived isotopes - 9°Sr and, to a smaller extent, ¹³7Cs and ²³9Pu) and then migrated into Ozyorsk prior to the conception of their children (75 individuals, 33 family trios). Comparison group (control) included parents and their offspring who are Ozyorsk residents never residing in the areas contaminated by radionuclides (65 individuals, 23 family trios). All the investigated individuals from the compared groups were of the corresponding age and gender and had never worked at nuclear facilities. Blood samples were obtained in the periods that excluded oncological, acute infectious and inflammatory diseases of any acute stages of chronic processes. Concentration of immune cells was measured by flow cytometer (Beckman Coulter, USA) using special monoclonal antibodies of the same manufacturer in a licensed medical center "Familia" (Chelyabinsk). The objective of the work is to assess the immune status in parents who migrated from contaminated areas prior to the conception of children and in their 1st generation offspring not exposed to radiation. Alterations of the immune status in the form of increase or, to a smaller extent, decrease of concentration of lymphocytes with effector and/or regulatory functions (B-1, T-helpers, NK, T-NK, late precursors of T-1 and T-1 of late activation) in blood of exposed parents and their offspring were detected in comparison with the results in the control group; that could possibly be related to the stimulation effect of low doses that support activation, proliferation and development of compensatory imbalance in the immune system and immunodeficiency in parents of the main group and in their offspring. In order to reveal the mechanisms of the detected alterations the interrelation between immune damage and incidence, of diseases among the cohorts involved in the current work will be studied further.

A review of job-exposure matrix methodology for application to workers exposed to radiation from internally deposited plutonium or other radioactive materials.

Any potential health effects of radiation emitted from radionuclides deposited in the bodies of workers exposed to radioactive materials can be directly investigated through epidemiological studies. However, estimates of radionuclide exposure and consequent tissue-specific doses, particularly for early workers for whom monitoring was relatively crude but exposures tended to be highest, can be uncertain, limiting the accuracy of risk estimates. We review the use of job-exposure matrices (JEMs) in peer-reviewed epidemiological and exposure assessment studies of nuclear industry workers exposed to radioactive materials as a method for addressing gaps in exposure data, and discuss methodology and comparability between studies. We identified nine studies of nuclear worker cohorts in France, Russia, the USA and the UK that had incorporated JEMs in their exposure assessments. All these JEMs were study or cohort-specific, and although broadly comparable methodologies were used in their construction, this is insufficient to enable the transfer of any one JEM to another study. Moreover there was often inadequate detail on whether, or how, JEMs were validated. JEMs have become more detailed and more quantitative, and this trend may eventually enable better comparison across, and the pooling of, studies. We conclude that JEMs have been shown to be a valuable exposure assessment methodology for imputation of missing exposure data for nuclear worker cohorts with data not missing at random. The next step forward for direct comparison or pooled analysis of complete cohorts would be the use of transparent and transferable methods.

A Bayesian analysis of plutonium exposures in Sellafield workers.

The joint Russian (Mayak Production Association) and British (Sellafield) plutonium worker epidemiological analysis, undertaken as part of the European Union Framework Programme 7 (FP7) SOLO project, aims to investigate potential associations between cancer incidence and occupational exposures to plutonium using estimates of organ/tissue doses. The dose reconstruction protocol derived for the study makes best use of the most recent biokinetic models derived by the International Commission on Radiological Protection (ICRP) including a recent update to the human respiratory tract model (HRTM). This protocol was used to derive the final point estimates of absorbed doses for the study. Although uncertainties on the dose estimates were not included in the final epidemiological analysis, a separate Bayesian analysis has been performed for each of the 11 808 Sellafield plutonium workers included in the study in order to assess: A. The reliability of the point estimates provided to the epidemiologists and B. The magnitude of the uncertainty on dose estimates. This analysis, which accounts for uncertainties in biokinetic model parameters, intakes and measurement uncertainties, is described in the present paper. The results show that there is excellent agreement between the point estimates of dose and posterior mean values of dose. However, it is also evident that there are significant uncertainties associated with these dose estimates: the geometric range of the 97.5%:2.5% posterior values are a factor of 100 for lung dose, 30 for doses to liver and red bone marrow, and 40 for intakes: these uncertainties are not reflected in estimates of risk when point doses are used to assess them. It is also shown that better estimates of certain key HRTM absorption parameters could significantly reduce the uncertainties on lung dose in future studies.

Chromosome aberrations in workers with exposure to α-particle radiation from internal deposits of plutonium: expectations from in vitro studies and comparisons with workers with predominantly external γ-radiation exposure.

mFISH analysis of chromosome aberration profiles of 47 and 144 h lymphocyte cultures following exposure to 193 mGy α-particle radiation confirmed that the frequency of stable aberrant cells and stable cells carrying translocations remains constant through repeated cell divisions. Age-specific rates and in vitro dose-response curves were used to derive expected translocation yields in nine workers from the Mayak nuclear facility in Russia. Five had external exposure to γ-radiation, two of whom also had exposure to neutrons, and four had external exposure to γ-radiation and internal exposure to α-particle radiation from incorporated plutonium. Doubts over the appropriateness of the dose response used to estimate translocations from the neutron component made interpretation difficult in two of the workers with external exposure, but the other three had translocation yields broadly in line with expectations. Three of the four plutonium workers had translocation yields in line with expectations, thus supporting the application of the recently derived in vitro α-particle dose response for translocations in stable cells. Overall this report demonstrates that with adequate reference in vitro dose-response curves, translocation yield has the potential to be a useful tool in the validation of red bone marrow doses resulting from mixed exposure to external and internal radiation.

[Influence of Professional Contact with Plutonium-239 on Indicators of the Immune Status of the Personnel at Siberian Chemical Plant].

The results of the examination and monitoring of the personnel at the Siberian Chemical Plant (SChP) and adult population of Seversk are presented. The results of primary examination of the personnel who professionally contact the ionizing radiation (IR) from external sources and incorporated 239Pu showed that clinical symptoms of dysfunction of the immune system manifested themselves with a frequency of 75.30%. Infectious-inflammatory diseases (46.95%) and the combined pathology of infectious and allergic character (20.12%) were the most widespread. The allergic diseases (AD) without manifestations of an infectious component were observed not often (7.62%). The monitoring which was carried out for 10 years revealed a decrease in a percentage of persons with clinical signs of disorders of the immune system up to 60.68% among the personnel at the Chemical-Steel Plant and even more among the whole group of the studied personnel at SChP--49.68% (389 : 783). Among the population their frequency made up 51.78%. Features of clinical manifestations of dysfunction ofthe immune system depending on accumulation of 239Pu in the organism are established. Similar dynamics of infectious and infectious and allergic syndromes is revealed when the activity of 239Pu is 40 nCi. AD frequency reliably increased .when the activity of 239Pu is 20 nCi, but if accumulation is higher than 20-40 nCi it decreases and again increases when the activity is over 40 nCi. Pathologies of infectious and allergic genesis are most often observed when the content of 239Pu in an organism is over 40 nCi. Indicators of the immune status (IS) of the personnel at SChP with incorporated 239Pu are analyzed. 59 people--carriers of 239Pu and 408 people without 239Pu accumulated in an organism are examined. In comparison with the control, IS indicators characteristic for all dose loading groups are revealed: increase of lymphocytes, existence of dissociation in indicators of relative and absolute values of the T-cellular link, CD16+56+(-) NK-cells and B-lymphocytes with increase of absolute values, decrease in markers of activation of HLA-DR+ and CD95+, increase of B-lymphocytes and low level of serum IgM. Features of IS in comparison with the group of the personnel with the absence of 239Pu in an organism and indicators of IS which depend on the activity of 239Pu are established. Among them are a decrease in the percentage of persons with increased number of lymphocytes with increased beam loading; increase of NK-T-cells when the activity of 239Pu is 10-20 nCi and the highest value at doses over40 nCi; the dynamics of CD16+56(+)-lymphocytes with the increase of the contents and a percentage of persons with the increase of the activity above 40 nCi; the highest frequenc of a regulatory imbalance with high frequency decrease of CD8(+)-T-lymphocytes at the content of 239Pu > 0-10 nCi; decrease in indicators of B-lymphocytes and serum IgA with an increase in the activity of 239Pu with the lowest values under internal radiation over 40 nCi; decrease in the percentage of persons with a weakening expression of HLA-DR+ with the increase in dose loading.

[PLUTONIUM AND LIFETIME REDUCTION AMONG PROFESSIONAL WORKERS FSUE].

The objective of the study is the assessment of lifetime in the cohort of Mayak PA workers employed in 1948-1958 and exposed to incorporated Pu-239. The decrease of age at death 5.2 years among males and 6.6 years among females, and after the start of work--6.9 years among males and 7.7 years among females, with the increase of Pu-239 incorporation was shown. The association of the raised mortality rate from tumour causes is shown both among males and females, mainly due to malignant neoplasms of lung and live; which are organs of Pu-239 main deposition. For the first time related to Pu-239 incorporation decrease of age at death from tumour and non-tumour causes of main and secondary organs of deposition both among males and females was revealed. To assess the reduction of lifetime Years of Potential Life Lost (YPLL) were calculated per 10(5) person-years of potential life based on European gender standard. The calculations based on the obtained estimations showed significant dependence of YPLL on the level of Pu-239 incorporation. At that the main contribution to the increase of YPLL, i.e. to lifetime reduction, was due to radiation-induced decrease of the age at death as compared to radiation-induced increase of mortality rates.

Solid cancer incidence other than lung, liver and bone in Mayak workers: 1948-2004.

BACKGROUND: Cancer incidence in the Mayak Production Association (PA) cohort was analysed to investigate for the first time whether external gamma-ray and internal plutonium exposure are associated with raised incidence of solid cancers other than lung, liver and bone (other solid cancers). METHODS: The cohort includes 22,366 workers of both sexes who were first employed between 1948 and 1982. A total of 1447 cases of other solid cancers were registered in the follow-up period until 2004. The Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to plutonium and external gamma-ray. RESULTS: A weak association was found between cumulative exposure to external gamma-ray and the incidence of other solid cancers (ERR/Gy=0.07; 95% confidence intervals (CIs): 0.01-0.15), but this association lost its significance after adjusting for internal plutonium exposure. There was no indication of any association with plutonium exposure for other solid cancers. Among 16 individual cancer sites, there was a statistically significant association with external exposure for lip cancer (ERR/Gy=1.74; 95% CI: 0.37; 6.71) and with plutonium exposure for pancreatic cancer (ERR/Gy=1.58; 95% CI; 0.17; 4.77). CONCLUSION: This study of Mayak workers does not provide evidence of an increased risk of other solid cancers. The observed increase in the risk of cancer of the lip and pancreas should be treated with caution because of the limited amount of relevant data and because the observations may be simply due to chance.

Effectiveness of Surgical Excision Following Plutonium-contaminated Wounds: Inferences from Historical Cases.

ABSTRACT: As with any medical treatment, the decision to excise a wound contaminated with actinides is a risk-benefit analysis. The potential benefits of surgical excision following such contaminated wounds are reduction in the probability of stochastic effects, avoidance of local effects, and psychological comfort knowing that radioactive material deposited in the wound is prevented from being systemic. These benefits should be balanced against the potential risks such as pain, numbness, infection, and loss of function due to excision. To that end, the responsibility of an internal dosimetrist is to provide advice to both the patient and the treating physician about the likely benefits of excision that include, but not limited to, averted doses. This paper provides a review of the effectiveness of surgical excisions following plutonium-contaminated wounds and finds that excisions are highly effective at removing plutonium from wounds and at averting the doses they would have caused.

[The assessment of accumulated internal irradiation doses of the inhabitants of the populated areas in Republik Belarus after Chernobyl accident].

A new system of evaluation methods has been developed for the assessment of the accumulated internal irradiation doses in the inhabitants of the populated areas of the Republic of Belarus that were contaminated by the Chernobyl radionuclides. The system is based on the results of WBC measurements. The model is based on the WBC-results of the State Dosimetric Register for the period of 1987-2010. The dose assessment model is based on the classification of the populated areas, on the regional features of the soils through which 137Cs can enter into the locally grown and produced foods. The model is also based on building the regressive correlations of accumulated internal doses to the contamination density of the territory of a populated area. Such regressive correlations are made for each region. The influence of indirect factors of dose forming was taken into consideration in the dose assessment. Among these factors are the population of the area, and the amount of forested territory around it, which were taken as correction coefficients. The coefficients were determined from the regressive correlation of the correction coefficients to a specific area of forest for each region. So called "countermeasure factor" was used for specification of other model results.

[Risk of cerebrovascular disease incidence in the cohort of Mayak production association workers first employed during 1948-1958].

Incidence of cerebrovascular diseases (CVD) has been studied in a cohort of 12210 workers first employed at one of the main plants (reactors, radiochemical or plutonium) of the Mayak nuclear facility during 1948-1958 and followed up to the end of 2000. Information on external gamma doses is available for virtually all (99.9%) of these workers; the mean (+/- one standard deviation) total gamma dose was 0.91 +/- 0.95 Gy (99% percentile 3.9 Gy) for men and 0.65 +/- 0.75 Gy (99% percentile 2.99 Gy) for women. Plutonium body burden was measured only for 30.0% of workers. Amongst those monitored, the mean (+/- standard deviation) cumulative liver dose from plutonium alpha exposure was 0.40 +/- 1.15 Gy (99% percentile 5.88 Gy) for men and 0.81 +/- 4.60 Gy (99% percentile 15.95 Gy) for women 4418 cases (first diagnosis) of CVD were identified in the studied cohort. A statistically significant increasing trend in CVD incidence with total external gamma dose was revealed after adjustment for non-radiation factors and internal exposure from incorporated plutonium-239. Excess relative risk per Gy was 0.464 (95% confidence interval 0.360-0.567). Incidence of CVD was statistically significantly higher for the workers chronically exposed to external gamma rays at a dose above 1.0 Gy A statistically significant increasing trend in CVD incidence with internal liver dose from plutonium alpha exposure was observed after adjustment for non-radiation factors and external exposure. ERR per Gy was 0.155 (95% confidence interval 0.075-0.235). CVD incidence was statistically significantly higher among workers with a plutonium liver dose above 0.1 Gy, although the trend estimates differed between workers at different plants. The incidence risk estimates for external radiation are generally compatible with estimates from the study of Chernobyl clean-up workers, although the incidence data point to higher risk estimates compared to those from the Japanese A-bomb survivors.

[Mortality risk of cardiovascular diseases for occupationally exposed workers].

Results of the risk analysis of mortality from ischemic heart disease (IHD) in the cohort of Mayak nuclear workers (18763 individuals) first employed in 1948-1972, with follow-up to 31.12.2005, were summarized. The mortality risk of IHD in the cohort of Mayak workers depended on the non-radiation factors such as gender, age, calendar period, smoking, alcohol consumption, arterial hypertension, body mass index. There was no statistically significant relationship between mortality from 1HD and total external dose. The risk of mortality from IHD was significantly higher for workers exposed to the total absorbed dose to liver > 0.025 Gy from internal alpha-radiation. There was a significantly increasing trend (ERR/Gy) of the IHD mortality with the total absorbed dose to liver from internal alpha-radiation due to incorporated plutonium. However, there was a decreasing trend of ERR/Gy with restriction of the follow-up to Ozyorsk and adjustment for the external dose.