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PubMed1997

The Semipalatinsk nuclear test site: a first assessment of the radiological situation and the test-related radiation doses in the surrounding territories.

As a result of atmospheric nuclear tests at the Semipalatinsk test site 'Polygon', adjacent territories were contaminated by radionuclide fallout. The population of some districts in the Semipalatinsk oblast were exposed to elevated levels of radiation. Contamination and exposure mostly resulted from early atmospheric tests. The radiological situation of the Semipalatinsk oblast is described. Effective dose estimates due to external and internal exposure attributable to the 1949 and 1953 tests in villages near the Polygon range from 70 mSv to 4470 mSv.

Air Pollution, Radioactive↗

PubMed1998

Temporal variation of thoron decay product concentration in the atmosphere and comparison with radon decay product concentration.

Seasonal and long-term variation of the airborne 212Pb concentration, representative of the equilibrium equivalent concentration of thoron decay products (EECRn220), was investigated from 1989 through 1996 at a semi-natural location in southern Germany. Continuous measurement yielded a long-term average concentration of 0.082 Bq m-3, while daily mean concentrations varied from < or = 0.01 to 0.34 Bq m-3. An average annual effective dose of 1.4 mSv due to outdoor thoron progeny concentration was estimated. This is about 2% of the dose due to the average short-lived radon progeny concentration (EECRn222) of 8.4 Bq m-3 measured for this location in the same period. In most years the seasonal pattern of 212Pb activity concentration in the atmosphere is characterized by two maxima: the first in May and the second one in September. Low concentrations are observed from November through February of each year. This is in contrast to the behaviour of the short-lived 222Rn progeny which exhibit enhanced concentrations exactly during these months. The most probable reason for the different temporal behaviour of 212Pb is the extremely reduced flux of thoron gas from the ground during the winter months.

Air Pollutants, Radioactive↗

PubMed2001

Diurnal and seasonal variation of the equilibrium state between short-lived radon decay products and radon gas in ground-level air.

To study seasonal and diurnal variations and the effect of meteorological parameters, the equilibrium factor F (i.e. the ratio of equilibrium equivalent radon daughter concentration and radon gas concentration) was determined as a result of measurements on a test field at Munich-Neuherberg, Germany, continuously from October 1995 through March 1997. On average, F was found to be 0.62+/-0.09 (95% confidence level). The time series of F showed no distinct seasonal variations. Nevertheless, typical diurnal variations as well as seasonal variations of the diurnal behaviour were observed. Generally, F was found to be increased in the early afternoon, i.e. under conditions of enhanced vertical mixing in the atmosphere. The daily differences between high and low values of F depended on the season. On average, low F values were characteristic for days with precipitation and high wind speed, i.e. under turbulent atmospheric conditions. Therefore, taking daily mean values into account, F was found to be positively correlated with the aerosol concentration, although a relationship between the diurnal behaviour of the aerosol concentration and that of F was not detectable.

Air Pollutants, Radioactive↗

PubMed2005

Childhood leukaemia incidence in Hungary, 1973-2002. Interpolation model for analysing the possible effects of the Chernobyl accident.

The incidence of childhood leukaemia in Hungary has yet to be reported, although data are available since the early 70s. The Hungarian data therefore cover the time before and after the Chernobyl nuclear accident (1986). The aim of this study was to assess the effects of the Chernobyl accident on childhood leukaemia incidence in Hungary. A population-based study was carried out using data of the National Paediatric Cancer Registry of Hungary from 1973 to 2002. The total number of cases was 2204. To test the effect of the Chernobyl accident the authors applied a new approach called 'Hypothesized Impact Period Interpolation'-model, which takes into account the increasing trend of childhood leukaemia incidence and the hypothesized exposure and latency times. The incidence of leukaemia in the age group 0-14 varied between 33.2 and 39.4 per million person-years along the observed 30 year period, and the incidence of childhood leukaemia showed a moderate increase of 0.71% annually (p = 0.0105). In the period of the hypothesized impact of the Chernobyl accident the incidence rate was elevated by 2.5% (95% CI: -8.1%; +14.3%), but this change was not statistically significant (p = 0.663). The age standardised incidence, the age distribution, the gender ratio, and the magnitude of increasing trend of childhood leukaemia incidence in Hungary were similar to other European countries. Applying the presented interpolation method the authors did not find a statistically significant increase in the leukaemia incidence in the period of the hypothesized impact of the Chernobyl accident.

Adolescent↗

PubMed2005

Assessment of potential atmospheric transport and deposition patterns due to Russian Pacific Fleet operations.

A probabilistic analysis of atmospheric transport and deposition patterns from two nuclear risk sites-Kamchatka and Vladivostok-situated in the Russian Far East to countries and geographical regions of interest (Japan, China, North and South Koreas, territories of the Russian Far East, State of Alaska, and Aleutian Chain Islands, US) was performed. The main questions addressed were the following: Which geographical territories are at the highest risk from hypothetical releases at these sites? What are the probabilities for radionuclide atmospheric transport and deposition on different neighboring countries in case of accidents at the sites? For analysis, several research tools developed within the Arctic Risk Project were applied: (1) isentropic trajectory model to calculate a multiyear dataset of 5-day forward trajectories that originated over the site locations at various altitudes; (2) DERMA long-range transport model to simulate 5-day atmospheric transport, dispersion, and deposition of 137Cs for 1-day release (at the rate of 10(10) Bq/s); and (3) a set of statistical methods (including exploratory, cluster, and probability fields analyses) for evaluation of trajectory and dispersion modeling results. The possible impact (on annual, seasonal, and monthly basis) of selected risk sites on neighboring geographical regions is evaluated using a set of various indicators. For trajectory modeling, the indicators examined are: (1) atmospheric transport pathways, (2) airflow probability fields, (3) fast transport probability fields, (4) maximum possible impact zone, (5) maximum reaching distance, and (6) typical transport time fields. For dispersion modeling, the indicators examined are: (1) time integrated air concentration, (2) dry deposition, and (3) wet deposition. It was found for both sites that within the boundary layer the westerly flows are dominant throughout the year (more than 60% of the time), increasing with altitude of free troposphere up to 85% of the time. For the Kamchatka site, the US regions are at the highest risk with the average times of atmospheric transport ranging from 3 to 5.1 days and depositions of 10(-1) Bq/m2 and lower. For the Vladivostok site, the northern China and Japan regions are at the highest risk with the average times of atmospheric transport of 0.5 and 1.6 days, respectively, and depositions ranging from 10(0) to 10(+2) Bq/m2. The areas of maximum potentially impacted zones are 30 x 10(4) km2 and 25 x 10(4) km2 for the Kamchatka and Vladivostok sites, respectively.

Air Movements↗

PubMed2006

Geographic variability in radon exhalation at a rehabilitated uranium mine in the Northern Territory, Australia.

In this study, dry season radon flux densities and radon fluxes have been determined at the rehabilitated Nabarlek uranium mine in northern Australia using conventional charcoal canisters. Environmental background levels amounted to 31+/- 15 milli Becquerel per m(2) per second (mBq m(-2) s(-1)). Radon flux densities within the fenced rehabilitated mine area showed large variations with a maximum of 6500 mBq m(-2) s(-1) at an area south of the former pit characterised by a disequilibrium between (226)Ra and (238)U. Radon flux densities were also high above the areas of the former pit (mean 971 mBq m(-2) s(-1)) and waste rock dump (mean 335 mBq m(-2) s(-1)). The lower limit for the total pre-mining radon flux from the fenced area (140 ha) was estimated to 214 kBq s(-1), post-mining radon flux amounted to 174 kBq s(-1). Our study highlights that the results of radon flux studies are vitally dependant on the selection of individual survey points. We suggest the use of a randomised system for both the selection of survey points and the placement of charcoal canisters at each survey point, to avoid over estimation of radon flux densities. It is also important to emphasize the significance of having reliable pre-mining radiological data available to assess the success of rehabilitation of a uranium mine site.

Air Pollutants, Radioactive↗

PubMed2006

Use of airborne gamma-ray spectrometry for environmental assessment of the rehabilitated nabarlek uranium mine, Australia.

This article describes an airborne gamma survey of a 7 x 5 km region around the rehabilitated Nabarlek uranium mine in northern Australia. An unusually tight line spacing (100 m) and low aircraft height (50 m) were used, enabling the survey to distinguish man-made structures such as ponds and accommodation areas, as well as creek lines. Positive correlations between airborne data and ground-based readings enabled an estimation of the average absorbed dose rate arising from terrestrial gamma radiation over large areas of the site to be derived. For the fenced minesite area this estimate was 0.31 micro Gy hr(- 1). The airborne survey data were found to be invaluable in helping to plan further ground-level investigations and showed promise as an assessment tool for rehabilitated minesites.

Air Pollutants, Radioactive↗

PubMed2006

Radiation exposure to the patient and operating room personnel during percutaneous nephrolithotomy.

INTRODUCTION: The increased use of fluoroscopy during percutaneous nephrolithotomy (PCNL) places the urologist and operating room personnel at an occupational risk for measurable radiation exposure. We evaluated the degree of radiation exposure received by the patient and operating room personnel at our endourology facility during PCNL. PATIENTS AND METHOD: The incident radiation dose to the patient and the urologist during 50 consecutive PCNL procedures was monitored using lithium fluoride thermo-luminescent dosimeter chips (TLD chips). A hand held radiation survey meter was used to measure the radiation in air at different positions occupied by various operating room personnel. The approximate distances of the various personnel from the X-ray tube were also measured. RESULTS: PCNL was performed upon 35 males and 15 females. The average time for the procedure was 75 minutes (range: 30-150 min). The mean fluoroscopy screening time during the procedure was 6.04 min (range 1.8-12.16 min) with a mean fluoroscopy tube potential of 68 kVp and a mean tube current of 2.76 mA. The mean radiation exposure dose to the patient was 0.56 mSv (SD +/- 0.35), while the mean incident radiation exposure to the finger of the urologist was 0.28 mSv (SD +/- 0.13). CONCLUSION: The various operating room personnel are within safe radiation dose limits during PCNL. Efficient fluoroscopy further reduces the radiation scatter. All occupational personnel should 'achieve as low as reasonably achievable' dose by adhering to good practices.

Adolescent↗

PubMed1980

Environmental pollution and pregnancy: risks and uncertainties for the fetus and infant.

Numerous environmental contaminants can affect the developing embryo, fetus, or infant. This essay explores such questions as these: What is the importance in mutagenesis and teratogenesis of macroenvironmental pollutants such as the heavy metals, dioxin derivatives, polychlorinated diphenyl compounds, and pesticides? What is the significance of microenvironmental pollutants (or social environmental factors) such as tobacco smoke, alcohol, and pharmacologic agents over which exposed individuals have considerable control? What are some of the ethical and legal implications of these toxins of which clinicians should be aware?

Air Pollutants, Radioactive↗

PubMed1968