Dissolution characteristics of uranium and lead in simulated lung fluid using fly ash samples from coal-fired power plants in the Czech Republic

Samples of fly ash, slag and boiler scale containing elevated amounts of uranium or lead (210Pb) from several coal-fired power stations in the Czech Republic were collected for an assessment of their dissolution parameters - the dissolution rates and their respective fractions in vitro. The dissolution data were fitted either by a biexponential model or by a triexponential model. The uranium 234U and 238U in the fly ash sample are classified as M-type. Similarly, type M could be attributed for most of the materials containing 210Pb. A complementary measurement of the activity concentrations of 210Pb in relation to the grain size confirmed that the radionuclide is deposited mainly in fine particles (<25 μm).

RADON INHALATION EXPERIMENTS TO TEST RADON EXHALATION KINETICS

Three experiments were conducted with a volunteer to test the kinetics of the 222Rn exhalation after a short-time exposure to an elevated 222Rn air concentration. Radon concentration in an exhaled air was measured, complemented by whole body counting of 222Rn decay products in a body. Exhaled activities are compared with the prediction of the recent ICRP biokinetic model for radon. While a rapid equilibration of the exhaled radon activity concentration with that in the air inhaled corresponded with the model, the measured 222Rn exhalation rate was significantly less than modelled. Five hours after termination of the inhalation phase, the radon concentration in the exhaled air decreased to levels expected for non-elevated indoor radon activity concentration. Whole body activities of the 222Rn decay products were found higher than expected. Inhalation of the unattached fraction or residual activity of decay products in the air inhaled may be the explanation.

ASSOCIATION OF 210Po CONTENT IN URINE WITH CONCENTRATION OF 222Rn IN DWELLINGS

Effect of indoor radon concentrations higher than 500 Bq m-3 in dwellings on excretion of 210Po was studied in 28 volunteers. The study was further augmented by following eight individuals from the group for 5 months at 1-month intervals. Association between 222Rn concentration in homes and 210Po excretion was found when the dataset containing values of the studied 27 subjects was combined with data on 40 Prague inhabitants from the previous study. Sources of uncertainties involved in the analysis are discussed.

DETERMINATION OF TOLERANCE LEVELS IN RADIOTHERAPY DOSIMETRY BASED ON STATISTICAL INTERFERENCE

The most important dosimetry quantity that is determined at radiotherapy centers is the absorbed dose to water for external beams. Fixed tolerances for absorbed doses measured under reference conditions with an ionization chamber for high-energy photon and electron beams are usually 2 and 3%, respectively, regardless of uncertainties of the input variables and other conditions during evaluation. In reality, this agreement should be evaluated considering the uncertainties of the input variables because they affect the size of the random deviations of the measurements from their true values. The aim of this work was to develop a new approach to evaluate the agreement between measured and reported values based on statistical interference rather than to use fixed tolerance levels. The proposed method considers different scenarios that can occur during the evaluation of agreement. Because the method is described in general, it can be used in all similar situations when partial uncertainties can be established.

238U CONTENT IN URINE OF URANIUM MINERS AND ITS MODELED VALUES

The aim of the study is to make a comparison of daily 238U excretion in urine among 115 active uranium miners and its modeled values obtained from inhalation intake of long-lived alpha emitters as measured by personal dosemeters and assessed by biokinetic models for different absorption parameters settings for inhaled uranium. A total of 144 spot samples of urine were collected. The 238U content was measured using high-resolution inductively coupled plasma mass spectrometry method. To obtain estimates of the daily excreted values, the daily values were calculated according to the expected daily excretion of creatinine assessed individually for each miner. When determining the relation between the experimentally found data and the modeled data, a high emphasis was placed on uncertainty of the both compared quantities. All the tested absorption parameters settings produced in average 1.4-4.7-fold higher values than the experimentally found values in the urine.

Urinary excretion of uranium in adult inhabitants of the Czech Republic

The main aim of this study was to determine and evaluate urinary excretion of uranium in the general public of the Czech Republic. This value should serve as a baseline for distinguishing possible increase in uranium content in population living near legacy sites of mining and processing uranium ores and also to help to distinguish the proportion of the uranium content in urine among uranium miners resulting from inhaled dust. The geometric mean of the uranium concentration in urine of 74 inhabitants of the Czech Republic was 0.091 mBq/L (7.4 ng/L) with the 95% confidence interval 0.071-0.12 mBq/L (5.7-9.6 ng/L) respectively. The geometric mean of the daily excretion was 0.15 mBq/d (12.4 ng/d) with the 95% confidence interval 0.12-0.20 mBq/d (9.5-16.1 ng/d) respectively. Despite the legacy of uranium mines and plants processing uranium ore in the Czech Republic, the levels of uranium in urine and therefore, also human body content of uranium, is similar to other countries, esp. Germany, Slovenia and USA. Significant difference in the daily urinary excretion of uranium was found between individuals using public supply and private water wells as a source of drinking water. Age dependence of daily urinary excretion of uranium was not found. Mean values and their range are comparable to other countries, esp. Germany, Slovenia and USA.

International intercomparison of measuring instruments for radon/thoron gas and radon short-lived daughter products in the NRPI Prague

During the 7th European Conference on Protection Against Radon at Home and at Work held in the autumn of 2013 in Prague, the second intercomparison of measuring instruments for radon and its short-lived decay products and the first intercomparison of radon/thoron gas discriminative passive detectors in mix field of radon/thoron were organised by and held at the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. In total, 14 laboratories from 11 different countries took part in the 2013 NRPI intercomparison. They submitted both continuous monitors for the measurement of radon gas and equivalent equilibrium radon concentration in a big NRPI chamber (48 m3) and sets of passive detectors including radon/thoron discriminative for the measurement of radon gas in the big chamber and thoron gas in a small thoron chamber (150 dm3).

[Criteria for perioperative risk evaluation--non-cardiac surgery]

The paper presents criteria used to evaluate surgical risks associated with non-cardiac surgical procedures.

[The decrease in morbidity and mortality of patients with chronic forms of ischemic heart disease is the result of conservative treatment]

Article presents actual comparison of therapeutic methods for patients with chronic coronary artery disease and their influence on morbidity and mortality. It calls attention to the insufficiently presented fact, that invasive methods, like percutaneous and surgical revascularization, despite great expectations, have not proved to lower morbidity and mortality in large randomized studies. In contrary several groups of drugs proved their efficiency many times. Paradoxically, the cheapest approach, life style intervention, seems to be the most efficient method for prognosis improvement of patients with chronic coronary artery disease.