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Curwen G.B.,University of Manchester | Sotnik N.V.,Southern Urals Biophysics Institute SUBI | Cadwell K.K.,Northumbria University | Azizova T.V.,Southern Urals Biophysics Institute SUBI | And 2 more authors.
Radiation and Environmental Biophysics | Year: 2015

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. © 2015, Springer-Verlag Berlin Heidelberg.

Moseeva M.B.,Southern Urals Biophysics Institute SUBI | Azizova T.V.,Southern Urals Biophysics Institute SUBI | Grigoryeva E.S.,Southern Urals Biophysics Institute SUBI | Haylock R.,Public Health England
Radiation and Environmental Biophysics | Year: 2014

The new Mayak Worker Dosimetry System 2008 (MWDS-2008) was published in 2013 and supersedes the Doses-2005 dosimetry system for Mayak Production Association (PA) workers. It provides revised external and internal dose estimates based on the updated occupational history data. Using MWDS-2008, a cohort of 18,856 workers first employed at one of the main Mayak PA plants during 1948-1972 and followed up to 2005 was identified. Incidence and mortality risks from ischemic heart disease (IHD) (International Classification of Diseases (ICD)-9 codes 410-414) and from cerebrovascular diseases (CVD) (ICD-9 codes 430-438) were examined in this cohort and compared with previously published risk estimates in the same cohort based on the Doses-2005 dosimetry system. Significant associations were observed between doses from external gamma-rays and IHD and CVD incidence and also between internal doses from alpha-radiation and IHD mortality and CVD incidence. The estimates of excess relative risk (ERR)/Gy were consistent with those estimates from the previous studies based on Doses-2005 system apart from the relationship between CVD incidence and internal liver dose where the ERR/Gy based on MWDS-2008 was just over three times higher than the corresponding estimate based on Doses-2005 system. Adjustment for smoking status did not show any effect on the estimates of risk from internal alpha-particle exposure. © Springer-Verlag Berlin Heidelberg 2014.

Suslova K.G.,Southern Urals Biophysics Institute SUBI | Sokolova A.B.,Southern Urals Biophysics Institute SUBI | Efimov A.V.,Southern Urals Biophysics Institute SUBI | Miller S.C.,University of Utah
Health Physics | Year: 2013

Americium-241(241Am) is the second most significant radiation hazard after 239Pu at some of the Mayak Production Association facilities. This study summarizes current data on the accumulation, distribution, and excretion of americium compared with plutonium in different organs from former Mayak PA workers. Americium and plutonium were measured in autopsy and bioassay samples and correlated with the presence or absence of chronic disease and with biological transportability of the aerosols encountered at different workplaces. The relative accumulation of 241Am was found to be increasing in the workers over time. This is likely from 241Pu that increases with time in reprocessed fuel and from the increased concentrations of 241Am and 241Pu in inhaled alpha-active aerosols. While differences were observed in lung retention with exposures to different industrial compounds with different transportabilities (i.e., dioxide and nitrates), there were no significant differences in lung retention between americium and plutonium within each transportability group. In the non-pulmonary organs, the highest ratios of 241Am/ 241Am + ΣPu were observed in the skeleton. The relative ratios of americium in the skeleton versus liver were significantly greater than for plutonium. The relative amounts of americium and plutonium found in the skeleton compared with the liver were even greater in workers with documented chronic liver diseases. Excretion rates of 241Am in "healthy" workers were estimated using bioassay and autopsy data. The data suggest that impaired liver function leads to reduced hepatic Am retention, leading to increased 241Am excretion. Copyright © 2013 Health Physics Society.

Kuznetsova I.S.,Southern Urals Biophysics Institute SUBI | Labutina E.V.,Southern Urals Biophysics Institute SUBI | Hunter N.,Public Health England
PLoS ONE | Year: 2016

Incidence of all types of lymphatic and hematopoietic cancers, including Hodgkin's lymphoma, non-Hodgkin's lymphoma,multiplemyeloma, acute and chronicmyeloid leukemia (AML and CML respectively), chronic lymphocytic leukemia (CLL) and other forms of leukemia have been studied in a cohort of 22,373 workers employed at the Mayak Production Association (PA) main facilities during 536,126 person-years of follow-up from the start of employment between 1948 and 1982 to the end of 2004. Risk assessment was performed for both external gamma-radiation and internal alpha-exposure of red bone marrow due to incorporated Pu-239 using Mayak Workers Dosimetry System 2008 taking into account non-radiation factors. The incidence of leukemia excluding CLL showed a non-linear dose response relationship for external gamma exposure with exponential effect modifiers based on time since exposure and age at exposure. Among the major subtypes of leukemia, the excess risk of AML was the highest within the first 2-5 years of external exposure (ERR per Gy: 38.40; 90% CI: 13.92-121.4) and decreased substantially thereafter, but the risks remained statistically significant (ERR per Gy: 2.63; 90% CI: 0.07-12.55). In comparison, excess CML first occurred 5 years after exposure and decreased about 10 years after exposure, although the association was not statistically significant (ERR per Gy: 1.39; 90% CI: -0.22-7.32). The study found no evidence of an association between leukemia and occupational exposure to internal plutonium ERR per Gy 2.13; 90% CI: <0-9.45). There was also no indication of any relationship with either external gamma or internal plutonium radiation exposure for either incidence of Hodgkin or non-Hodgkin lymphoma or multiplemyeloma. © 2016 Kuznetsova et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Labutina E.V.,Southern Urals Biophysics Institute SUBI | Kuznetsova I.S.,Southern Urals Biophysics Institute SUBI | Hunter N.,Public Health England | Harrison J.,Public Health England | Koshurnikova N.A.,Southern Urals Biophysics Institute SUBI
Health Physics | Year: 2013

This paper presents the results of analyses of the incidence of malignant neoplasms in lung, liver, and bone and associated connective tissues among Mayak nuclear workers exposed to both internally incorporated plutonium and to external gamma radiation. The study cohort included 22,373 individuals employed at the reactors and radiochemical and plutonium production facilities of the Mayak nuclear complex during 1948-1982 and followed up to the end of 2004. All analyses were carried out by Poisson regression, and the doses used were derived using a recently available update of organ doses, Mayak doses-2008. There was clear evidence for the linear association between internal plutonium dose and the risk of lung cancer. For males, there was evidence of a significant internal plutonium dose response for all histological types of lung cancer evaluated (adenocarcinoma, squamous-cell, and other epithelial); the estimated excess relative risk (ERR)/Gy for adenocarcinoma was the largest (ERR/Gy = 32.5; 95% CI: 16.3; 71.9), about 11-fold higher than that for squamous-cell lung cancer (ERR/Gy = 3.1; 95% CI: 0.3; 9.1). The relationship between liver cancer risk and plutonium exposure was best described by a linear-quadratic (LQ) function, but the LQ effect was diminished after restricting internal doses <2 Gy. Hepatocellular cancer was the most frequently observed type of liver cancer associated with internal plutonium exposure, and hemangiosarcomas were exclusively observed only at high internal plutonium doses (>4 Gy). For malignant neoplasms of bone and associated connective tissues, the trend was not statistically significant in relation to internal plutonium dose, but a statistically significantly higher risk (RR=13.7; 95% CI= 3.0; 58.5) was found among unmonitored female plutonium workers who were employed in the most hazardous plutonium production facility commissioned prior to 1950. Copyright © 2013 Health Physics Society.

Hunter N.,Public Health England | Kuznetsova I.S.,Southern Urals Biophysics Institute SUBI | Labutina E.V.,Southern Urals Biophysics Institute SUBI | Harrison J.D.,Public Health England
British Journal of Cancer | Year: 2013

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. © 2013 Cancer Research UK.

Suslova K.G.,Southern Urals Biophysics Institute SUBI | Khokhryakov V.F.,Southern Urals Biophysics Institute SUBI | Sokolova A.B.,Southern Urals Biophysics Institute SUBI | Miller S.C.,University of Utah
Health Physics | Year: 2012

Plutonium-238 ( 238Pu) has a half-life of about 87.7 y and thus a higher specific activity than 239Pu. It is used in radioisotope thermoelectric generators and is a substantial source of plutonium alpha-radiation in spent nuclear fuels. Early animal studies demonstrated differences in the biokinetics of inhaled oxides of 238Pu and 239Pu with 238Pu having a substantially more rapid translocation from the lungs to the systemic organs, particularly the skeleton. This resulted in the predominant occurrence of skeletal cancers in animals exposed to 238Pu oxides but lung cancers in those with exposures to 239Pu oxides. The anatomical distribution of osteogenic sarcomas seen in animal studies was similar to that observed with 239Pu and also in plutonium workers but differed from naturally occurring tumors. The in vivo "solubility" of 238Pu has been associated with the relative amounts of 238Pu/ 239Pu in the particles and calcination temperatures during the preparation of the dioxides. There is experimental evidence of in vivo 238Pu particle fragmentation attributed to nuclear recoil during radioactive decay. The resulting conversion of microparticles to nanoparticles may alter their interactions with macrophages and transport across epithelial barriers. There are few documented cases of human exposures, but the biokinetics appeared to depend on the chemical and physical nature of the aerosols. Robust human biokinetic and dosimetric models have not been developed, due in part to the lack of data. With the acceleration of nuclear technologies and the greater demand for reprocessing and/or disposal of spent nuclear fuels, the potential for human exposure to 238Pu will likely increase in the future. © 2012 Health Physics Society.

Simonetto C.,Helmholtz Center Munich | Azizova T.V.,Southern Urals Biophysics Institute SUBI | Grigoryeva E.S.,Southern Urals Biophysics Institute SUBI | Kaiser J.C.,Helmholtz Center Munich | And 2 more authors.
PLoS ONE | Year: 2014

We present an updated analysis of incidence and mortality from atherosclerotic induced ischemic heart diseases in the cohort of workers at the Mayak Production Association (PA). This cohort constitutes one of the most important sources for the assessment of radiation risk. It is exceptional because it comprises information on several other risk factors. While most of the workers have been exposed to external gamma radiation, a large proportion has additionally been exposed to internal radiation from inhaled plutonium. Compared to a previous study by Azizova et al. 2012, the updated dosimetry system MWDS-2008 has been applied and methods of analysis have been revised. We extend the analysis of the significant incidence risk and observe that main detrimental effects of external radiation exposure occur after more than about 30 years. For mortality, significant risk was found in males with an excess relative risk per dose of 0.09 (95% CI: 0.02; 0.16) Gy-1 while risk was insignificant for females. With respect to internal radiation exposure no association to risk could be established. © 2014 Simonetto et al.

Sotnik N.V.,Southern Urals Biophysics Institute SUBI | Osovets S.V.,Southern Urals Biophysics Institute SUBI | Scherthan H.,University of Ulm | Azizova T.V.,Southern Urals Biophysics Institute SUBI
Radiation and Environmental Biophysics | Year: 2014

We performed a study on the presence of chromosome aberrations in a cohort of plutonium workers of the Mayak production association (PA) with a mean age of 73.3 ± 7.2 years to see whether by multi-color fluorescence in situ hybridization (mFISH) translocation analysis can discriminate individuals who underwent occupational exposure with internal and/or external exposure to ionizing radiation 40 years ago. All Mayak PA workers were occupationally exposed to chronic internal alpha-radiation due to incorporated plutonium-239 and/or to external gamma-rays. First, we obtained the translocation yield in control individuals by mFISH to chromosome spreads of age-matched individuals and obtained background values that are similar to previously published values of an international study (Sigurdson et al. in Mutat Res 652:112-121, 2008). Workers who had absorbed a total dose of >0.5 Gy external gamma-rays to the red bone marrow (RBM) displayed a significantly higher frequency of stable chromosome aberrations relative to a group of workers exposed to <0.5 Gy gamma-rays total absorbed RBM dose. Thus, the translocation frequency may be considered to be a biological marker of external radiation exposure even years after the exposure. In a group of workers who were internally exposed and had incorporated plutonium-239 at a body burden >1.48 kBq, mFISH revealed a considerable number of cells with complex chromosomal rearrangements. Linear associations were observed for translocation yield with the absorbed RBM dose from external gamma-rays as well as for complex chromosomal rearrangements with the plutonium-239 body burden. © Springer-Verlag Berlin Heidelberg 2014.

Schadilov A.E.,Southern Urals Biophysics Institute SUBI | Belosokhov M.V.,Southern Urals Biophysics Institute SUBI | Levina E.S.,Southern Urals Biophysics Institute SUBI
Health Physics | Year: 2010

Plutonium isotopes (239Pu and 238Pu, and 241Am) with a total activity of 269 kBq were accidentally deposited in a puncture wound of the right index finger of a nuclear worker at the Mayak Production Association. Tissues surrounding the wound site contaminated with radionuclides were excised 4.5 h after the injury. Residual contamination within the wound amounted to 0.05% of the initial contamination. The 10-d therapy with CaNa3-diethylene triamine pentaacetate acid (CaNa3-DTPA) was performed in parallel with in vivo measurements of the wound site and daily urine bioassays. The wound intake of radionuclides was consistent with two forms of radioactive materials detected within the wound site, i.e., soluble compounds and a large fragment, which was completely removed by excision. On day 9 after the injury, the clearance rate from the wound site was 1.8 times higher than the rate predicted by the National Council on Radiation Protection and Measurements (NCRP) model for soluble compounds of plutonium and americium. The NCRP model parameters of transfer rates from the colloid and intermediate state (CIS) into soluble, and particles, aggregates and bound state (PABS) compartments were modified to eliminate any difference. As a result, a difference between the observed wound site radionuclide content and the value predicted by the modified wound model did not exceed 14% up to 9 days after the injury. For a longer period from 7 to 24 months, the value predicted by the modified model was consistent with results of the corresponding in vivo measurements. The treatment reduced the effective dose (50 years) from internal exposure by at least 480 times. The dose estimated (without accounting for a contribution of exposure dose to the regional lymph nodes draining the wound site) did not exceed 11 mSv. Copyright © 2010 Health Physics Society.

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