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Prouza Z.,National Radiation Protection Institute, Czech Republic
Radiation protection dosimetry | Year: 2010

During recent years, the assessment of possible radiological consequences of a terrorist attack associated with a release of radioactive substances (RaS) has been in the focus of interest of emergency preparedness and radiation protection specialists, as well as experts dealing with the dispersion of harmful substances in the atmosphere. Suitable tools for these analyses are applications of mathematical and physical models and simulation of this attack under 'realistic' conditions. The work presented here summarises the results of four tests, in which a RaS (a Tc-99 m solution) was dispersed over a free area with the use of an industrial explosive. Detection methods and techniques employed in these tests are described and values characterising the RaS dispersion--dose rates, surface activities in horizontal and vertical directions, volume activities, their space and time distributions and mass concentrations of aerosols produced after the explosion are presented and compared. These data will be applied to a comparison of outcomes of models used for the assessment of radiation accidents as well as in future field tests carried out under conditions of more complex geometry (indoor environment, terrain obstacles, etc.). Source


Tomasek L.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2014

Eleven underground miners studies evaluated the risk of lung cancer from exposure in underground mines. Nearly 68 000 miners were included in the joint study, contributing to nearly 2700 lung cancers. The resulting model of the Biological Effects of Ionizing Radiation (BEIR) VI Committee considered linear exposure response relationship, which was modified by time since exposure (TE), attained age and exposure rate. The effect of age at exposure (AE) was not explicitly evaluated. The presentation aims to show that the modifying effect of AE is substantial if time-since-exposure modification is simultaneously used in the model. When the excess relative risk per unit exposure (ERR/WLM) is adjusted for TE, the ERR/WLM corresponding to AE <15 is 0.013 and in subsequent categories decreased gradually up to the AE of 40 and more years, which was only 0.004. In comparison with the BEIRVI model, the present model predicts higher risks at younger ages and the risk decreases more rapidly. © The Author 2014. Published by Oxford University Press. All rights reserved. Source


Tomasek L.,National Radiation Protection Institute, Czech Republic
Journal of Radiological Protection | Year: 2012

The present study is based on 9978 Czech uranium miners with 1141 lung cancer deaths observed in an updated follow-up 1952-2010 and corresponding to 31years of mean follow-up. The objectives of the study are to obtain more reliable estimates for the exposure-response relationship, including factors that modify this relationship. Lung cancer in relation to cumulative exposure to radon decay products is linear with substantial modifications by time since exposure, age at exposure and exposure rate using exposure windows. The crude excess relative risk (ERR) per unit exposure in working level months (WLM) in the cohort is 0.0097 (90% confidence interval (CI) 0.0074-0.0127). The ERR/WLM corresponding to exposure rates below 7 working levels (WL) is substantially higher 0.0145 (90% CI 0.0109-0.0193). In the final model, the inverse effect of exposure rate is observed for high exposure rates >7WL with the ERR/WLM reduced to 31%. The ERR/WLM decreases to 32% and 9% in periods 20-29 and 30+years since exposure in comparison to the period of 5-19years since exposure. Simultaneously, the ERR/WLM decreases with age at exposure 63% and 49% at ages 30-39 and 40+years in comparison to age at exposure <30years. © 2012 IOP Publishing Ltd. Source


Holgye Z.,National Radiation Protection Institute, Czech Republic
Radiation Protection Dosimetry | Year: 2013

Excretion rates of 210Po and 210Pb in the urine were investigated in 40 healthy inhabitants of Prague (22 males, 18 females, age: 23-70 y, non-smokers). In 20 inhabitants the excretion rates of 210Po and 210Pb in faeces were also studied. The mean urinary excretion rates of 210Po and 210Pb were 4.1 and 6.0 mBq d-1, respectively. It was demonstrated, statistically, that the urinary excretion rates of 210Po and 210Pb are higher in men than those in women. The highest excretion rates of 210Po and 210Pb found in the participants were 10.8 and 16.6 mBq d-1, respectively. The mean activity ratio of 210Po/210Pb in the urine was 0.73. The mean excretion rates of 210Po and 210Pb in faeces were 56.5 and 54.6 mBq d-1. The mean activity ratio of 210Po210Pb in faeces was 1.0. © The Author 2013. Published by Oxford University Press. All rights reserved. Source


Tomasek L.,National Radiation Protection Institute, Czech Republic
Neoplasma | Year: 2012

The presented study reports lung cancer mortality in a cohort of 11 842 subjects exposed to high levels of radon covering the period 1961-2010. Exposure estimates were based on one year measurements of radon progeny in most houses of the study area (72%), missing values in the studied area were replaced by measurements in proxy houses (9%) and exposures outside the area (19%) were based on country radon mapping. Mean concentration of 448 Bq m-3 in the study is higher than the country mean by a factor of 5. By 2010, a total of 293 lung cancers were observed. The risk is significantly related to cumulated exposure with ERR/100Bq m-3 0.11 (90%CI: 0.04 - 0.25). This value is consistent with the risk coefficients in other indoor studies and also with the risks observed among uranium miners. The present follow-up demonstrated that increased incidence of lung cancer depends mainly on exposure from previous 5-19 years. The relative risk of lung cancer in the present study derived from this model is 1.53 (90%CI: 1.39 - 1.69). Source

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