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Masiuk S.V.,Ukrainian Academy of Sciences | Masiuk S.V.,Ukrainian Radiation Protection Institute | Shklyar S.V.,Taras Shevchenko National University | Kukush A.G.,Taras Shevchenko National University | And 3 more authors.
Biostatistics | Year: 2016

In this paper, the influence of measurement errors in exposure doses in a regression model with binary response is studied. Recently, it has been recognized that uncertainty in exposure dose is characterized by errors of two types: classical additive errors and Berkson multiplicative errors. The combination of classical additive and Berkson multiplicative errors has not been considered in the literature previously. In a simulation study based on data from radio-epidemiological research of thyroid cancer in Ukraine caused by the Chornobyl accident, it is shown that ignoring measurement errors in doses leads to overestimation of background prevalence and underestimation of excess relative risk. In the work, several methods to reduce these biases are proposed. They are new regression calibration, an additive version of efficient SIMEX, and novel corrected score methods. © 2016 The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. Source

Bonchuk I.,Ukrainian Radiation Protection Institute
Radioprotection | Year: 2011

Ukrainian Radiation Protection Institute has developed system for calculation of doses to the population living in the supervision zone of the NPP from atmospheric discharges of Nuclear Power Plants during normal operation. The system analyses daily meteorological data, and also daily and monthly atmospheric discharges of radionuclides. The developed system is applied for dose calculation for Ukrainian population and identification of radionuclides, which form considerable contribution to total doses (noble gases, H-3, I-131). A special attention has been given for variability of actual meteorological conditions and discharges. For example, it has been revealed the case when I-131 discharge from a Ukrainian NPP during 4 consecutive days has made 34 % of annual discharge (and 72% during 3 weeks). Variability of actual discharges is a result of changes in an operation mode of NPP unit and it is a typical situation for Ukrainian NPPs. Apparently, the similar situation can be typical for NPPs in another countries. Such results lead to necessity to consider possible variations of meteorological conditions and discharges for establishment of permissible levels (for example, by introduction of variability factor). © 2011 EDP Sciences. Source

Stocki T.J.,Radiation Protection Bureau | Telleria D.M.,International Atomic Energy Agency | Bergman L.,Radiation Protection Bureau | Proehl G.,International Atomic Energy Agency | And 12 more authors.
Radioprotection | Year: 2011

In January 2009, the IAEA EMRAS II (Environmental Modelling for Radiation Safety II) program was launched. The goal of the program is to develop, compare and test models for the assessment of radiological impacts to the public and the environment due to radionuclides being released or already existing in the environment; to help countries build and harmonize their capabilities; and to model the movement of radionuclides in the environment. Within EMRAS II, nine working groups are active; this paper will focus on the activities of Working Group 1: Reference Methodologies for Controlling Discharges of Routine Releases. Within this working group environmental transfer and dose assessment models are tested under different scenarios by participating countries and the results compared. This process allows each participating country to identify characteristics of their models that need to be refined. The goal of this working group is to identify reference methodologies for the assessment of exposures to the public due to routine discharges of radionuclides to the terrestrial and aquatic environments. Several different models are being applied to estimate the transfer of radionuclides in the environment for various scenarios. The first phase of the project involves a scenario of nuclear power reactor with a coastal location which routinely (continuously) discharges 60Co, 85Kr, 131I, and 137Cs to the atmosphere and 60Co, 137Cs, and 90Sr to the marine environment. In this scenario many of the parameters and characteristics of the representative group were given to the modellers and cannot be altered. Various models have been used by the different participants in this inter-comparison (PC-CREAM, CROM, IMPACT, CLRP POSEIDON, SYMBIOSE and others). This first scenario is to enable a comparison of the radionuclide transport and dose modelling. These scenarios will facilitate the development of reference methodologies for controlled discharges. © 2011 EDP Sciences. Source

Telleria D.,International Atomic Energy Agency | Cabianca T.,Public Health England | Proehl G.,International Atomic Energy Agency | Brown J.,Norwegian Radiation Protection Authority | And 4 more authors.
Annals of the ICRP | Year: 2015

The International Commission on Radiological Protection (ICRP) recently reinforced the international system of radiological protection, initially focused on humans, by identifying principles of environmental protection and proposing a framework for assessing impacts of ionising radiation on non-human species, based on a reference flora and fauna approach. For this purpose, ICRP developed dosimetric models for a set of Reference Animals and Plants, which are representative of flora and fauna in different environments (terrestrial, freshwater, marine), and produced criteria based on information on radiation effects, with the aim of evaluating the level of potential or actual radiological impacts, and as an input for decision making. The approach developed by ICRP for flora and fauna is consistent with the approach used to protect humans. The International Atomic Energy Agency (IAEA) includes considerations on the protection of the environment in its safety standards, and is currently developing guidelines to assess radiological impacts based on the aforementioned ICRP approach. This paper presents the method developed by IAEA, in a series of meetings with international experts, to enable assessment of the radiological impact to the marine environment in connection with the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 (London Convention 1972). This method is based on IAEA’s safety standards and ICRP’s recommendations, and was presented in 2013 for consideration by representatives of the contracting parties of the London Convention 1972; it was approved for inclusion in its procedures, and is in the process of being incorporated into guidelines. © The International Society for Prosthetics and Orthotics Reprints and permissions: sagepub.co.uk/journalsPermissions.nav Source

Little M.P.,U.S. National Institutes of Health | Kukush A.G.,Ukrainian Radiation Protection Institute | Kukush A.G.,Taras Shevchenko National University | Masiuk S.V.,Ukrainian Radiation Protection Institute | And 21 more authors.
PLoS ONE | Year: 2014

The 1986 accident at the Chernobyl nuclear power plant remains the most serious nuclear accident in history, and excess thyroid cancers, particularly among those exposed to releases of iodine-131 remain the best-documented sequelae. Failure to take dose-measurement error into account can lead to bias in assessments of dose-response slope. Although risks in the Ukrainian-US thyroid screening study have been previously evaluated, errors in dose assessments have not been addressed hitherto. Dose-response patterns were examined in a thyroid screening prevalence cohort of 13,127 persons aged <18 at the time of the accident who were resident in the most radioactively contaminated regions of Ukraine. We extended earlier analyses in this cohort by adjusting for dose error in the recently developed TD-10 dosimetry. Three methods of statistical correction, via two types of regression calibration, and Monte Carlo maximum-likelihood, were applied to the doses that can be derived from the ratio of thyroid activity to thyroid mass. The two components that make up this ratio have different types of error, Berkson error for thyroid mass and classical error for thyroid activity. The first regression-calibration method yielded estimates of excess odds ratio of 5.78 Gy-1 (95% CI 1.92, 27.04), about 7% higher than estimates unadjusted for dose error. The second regression-calibration method gave an excess odds ratio of 4.78 Gy-1 (95% CI 1.64, 19.69), about 11% lower than unadjusted analysis. The Monte Carlo maximum-likelihood method produced an excess odds ratio of 4.93 Gy-1 (95% CI 1.67, 19.90), about 8% lower than unadjusted analysis. There are borderline-significant (p= 0.101-0.112) indications of downward curvature in the dose response, allowing for which nearly doubled the low-dose linear coefficient. In conclusion, dose-error adjustment has comparatively modest effects on regression parameters, a consequence of the relatively small errors, of a mixture of Berkson and classical form, associated with thyroid dose assessment. Source

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