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PubMed1999

An application of the NCRP screening techniques to atmospheric radon releases from the former feed materials production center near Fernald, Ohio. National Council on Radiation Protection and Measurements.

The National Council on Radiation Protection and Measurements has published a series of screening models for releases of radionuclides to the environment. These models have been used to prioritize radionuclides being considered in environmental dose reconstructions. The NCRP atmospheric models are also accepted by the U.S. Nuclear Regulatory Commission for demonstrating compliance with the constraint on releases of airborne radioactive materials to the environment from licensees other than power reactors. This study tested the NCRP atmospheric techniques by comparing annual average predicted air concentrations of radon with measured radon concentrations at 14 locations 43 m to 598 m downwind of the former U.S. Department of Energy Feed Materials Production Center (FMPC) near Fernald, Ohio, for the period 2 July 1985 to 2 July 1986. Predictions were made using five different sets of meteorological data as input: (1) NCRP default values; (2) composite FMPC site data; (3) data from the Greater Cincinnati Airport; (4) data from the Dayton, Ohio, airport; and (5) data collected at Miami University, located near Oxford, Ohio. Following are the respective medians and ranges of the ratio of the predicted to observed annual radon air concentrations for each of these sources of meteorological data: (1) 5.2, 0.9-54; (2) 1.4, 0.1-8.2; (3) 0.7, 0.1-7.2; (4) 0.7, 0.1-8.4; and (5) 0.6, 0.1-10. The stated goal of the NCRP models is to predict doses that do not underpredict actual doses by greater than a factor of 10. In this comparison, all of the meteorological data produced air concentration predictions that meet this criteria. However, to ensure that final doses meet this criterion, one would need to carefully evaluate all assumptions used to calculate dose from each of these air concentrations.

Air Pollution, Radioactive↗
PubMed1987

Collection and characterization of aerosols from metal cutting techniques typically used in decommissioning nuclear facilities.

This study was designed to collect and characterize aerosols released during metal cutting activities typically used in decommissioning radioactively contaminated facilities. Such information can guide in the selection of appropriate control technologies for these airborne materials. Mechanical cutting tools evaluated included a multi-wheel pipe cutter, reciprocating saw, band saw, chop saw, and large and small grinding wheels. Melting-vaporization cutting techniques included an oxy-acetylene torch, electric arc cut rod and plasma torch. With the exception of the multi-wheel pipe cutter, all devices created aerosols in the respirable size range (less than 10 micron aerodynamic diameter). Time required to cut 2-in. (5-cm) Schedule 40, Type 304L, stainless steel ranged from about 0.6 min for the plasma torch to about 3.0 min for the reciprocating saw. Aerosol production rate ranged from less than 10 mg/min for the reciprocating saw to more than 3000 mg/min for the electric arc cut rod. Particles from mechanical tools were irregular in shape, whereas particles from vaporization tools were spheres and ultrafine branched-chain aggregates.

Aerosols↗
PubMed1997

Modeling the resuspension of radionuclides in Ukrainian regions impacted by Chernobyl fallout.

Following the 1986 Chernobyl event, large amounts of radioactive materials were deposited in nearby areas. Concentrations of various radionuclides were measured in air and surface soil. To study the resuspension of radioactive particulate, three different exposure situations were developed on the basis of the collected data under the auspices of the international BIOMOVS II (BIOspheric MOdel Validation Study) project. Modelers were asked to predict seasonal air concentrations and resuspension factors at several locations at different distances from Chernobyl for six successive years following the accident. Measurements of radionuclide deposition on topsoil were provided for each site along with information on soil, vegetation, land use, surface roughness, meteorology, and climate. In this paper, the three exposure situations are described, along with the initial data set provided to the modelers; two modeling approaches used to make the endpoint predictions are also presented. After the model predictions were submitted, the measured air concentrations and resuspension factors were released to the modelers. Generally, the predictions were well within an order of magnitude of the measured values. Time-dependent trends in predictions and measurements were in good agreement with one of the models, which (a) explicitly accounted for loss processes in soil and (b) used calibration to improve its predictive capabilities. Reasons for variations between predictions and measurements, suggestions for the improvement of models, and conclusions from the model validation study are presented.

Air Pollutants, Radioactive↗
PubMed1993

Caesium radioactivity in several selected species of honey.

In the years following the accident to the nuclear power plant at Chernobyl, investigations on several selected species of honey were done to determine their 134,137Cs contamination. Very low caesium activities were found in flower honeys, especially rape honeys. The transfer factor of caesium from the soil to the rape plant (Brassica napus var. oleifera) was found to be fCs = 0.116 +/- 0.080 in 1987, but only fCs = 0.017 +/- 0.017 in 1988, due to the lower availability of the caesium by gradual formation of water-insoluble chemical species. Honeydew honeys show a slightly higher 134,137Cs contamination. Honeydew is often produced by lice setting on spruces. Therefore, needles and twigs of spruces (Picea abies) were investigated and relatively high caesium contamination was found in fresh needles. A transfer factor for caesium from spruce needles to honeydew honey of about 0.1 was estimated. Finally, the caesium contamination in heather honeys and heather plants (Calluna vulgaris) was determined. Surprisingly higher factors between 2 and 40 were obtained for the caesium transfer from soil to Calluna vulgaris. These factors give a good explanation for the relatively high caesium contamination of heather honeys.

Air Pollutants, Radioactive↗
PubMed2004

Radon and thoron exposures for cave residents in Shanxi and Shaanxi provinces.

Measurements of natural radiation were carried out in cave dwellings distributed in the Chinese loess plateau. Those dwellings are located in Shanxi and Shaanxi provinces. Radon and thoron gas concentrations were measured using a passive integrating radon-thoron discriminative detector. Concentrations of thoron decay products were estimated from measurements of their deposition rates. A detector was placed at the center of each dwelling for 6 months and replaced with a fresh one for another 6 months. Measurements were conducted in 202 dwellings from August 2001 through August 2002. A short-term measurement was conducted during the observation period. In addition, gamma-ray dose rates were measured both indoors and outdoors with an electronic pocket dosimeter. Radioactivities in soil were determined by gamma-ray spectrometry with a pure germanium detector. Among 193 dwellings, indoor radon concentrations ranged from 19 to 195 Bq m(-3) with a geometric mean (GM) of 57 Bq m(-3), indoor thoron concentrations ranged from 10 to 865 Bq m(-3) with a GM of 153 Bq m(-3), and indoor equilibrium equivalent thoron concentrations ranged from 0.3 to 4.9 Bq m(-3) with a GM of 1.6 Bq m(-3). Arithmetic means of the gamma-ray dose rates were estimated to be 140 nGy h(-1) indoors and 110 nGy h(-1) outdoors. The present study revealed that the presence of thoron is not negligible for accurate radon measurements and thus that special attention should be paid to thoron and its decay products for dose assessment in such an environment. More systematic studies are necessary for a better understanding of thoron and its decay products.

Air Pollutants, Radioactive↗
PubMed2002

Uranium bioassay and radioactive dust measurements at some uranium processing sites in Egypt--health effects.

The safety of radiation workers in the uranium mining industry requires close and continuous monitoring of their working conditions. In this study, external radiation surveillance, radioactive dust monitoring and the bioassay of uranium were carried out in some processing sites. As dust represents one of the most important sources of radiation exposure in mills and mines, dust monitoring and bioassays were performed for a sample of workers on the production lines. The concentration of uranium in air ranged from 22.6 x 10(-7) to 11.1 x 10(-5) Bq cm-3, and the exposure levels ranged from 1 to 80 microSv h-1. Laser fluorimetric determination of uranium in urine samples showed concentrations in the range 8.4-29.2 micrograms L-1. Renal function parameters, such as serum creatinine and urea, and hematological parameters were determined in an attempt to correlate them with radiation exposure and the health status of the workers. Urine specimens collected from workers at the ore crushing and separation site showed elevated concentrations of uranium (up to 29.2 micrograms L-1) and a strong correlation between these concentrations and the registered serum creatinine. The mean uranium excretion in the investigated group was more than 20 times the occupational exposure decision level for urine uranium of 0.8 microgram L-1.

Adult↗
PubMed1997

Detecting strontium-89 removable contamination using a sodium iodide well counter.

UNLABELLED: Monitoring for 89Sr removable contamination is required for incoming DOT-labeled packages and work areas containing radioactivity. However, few nuclear medicine departments are equipped for liquid scintillation counting, which is the preferred method for detecting beta emitters. We investigated using a sodium iodide well counter to detect 89Sr through its bremsstrahlung photon production. METHODS: We used a manufacturer's 89Sr-chloride solution of known concentration and tested various parameters: type of tube, access of tube contents to air, volume of sample, type of wipe material and counting geometry. Liquid scintillation samples also were obtained. RESULTS: Initial counting efficiencies were 0.10-0.14 cpm/dpm for small volume (10-microliter) samples. The various parameters tested had either positive or negative effects on the system's efficiency to detect 89Sr. One set of samples, counted over time, demonstrated a calculated mean half-life of 50.8 days, which is similar to the 89Sr reported half-life of 50.5 days. Liquid scintillation samples demonstrated efficiencies of almost 1.0 cpm/dpm and a calculated mean half-life of 50.8 days, both as expected. CONCLUSION: This study demonstrates that 89Sr removable contamination can be detected sensitively using a sodium iodide well counter, but special considerations must be made when determining the system's counting efficiency.

Air Pollutants, Radioactive↗
PubMed2003

Iodine prophylaxis around the Semipalatinsk Nuclear Testing Site, Republic of Kazakstan.

OBJECTIVE: This study aimed to clarify the iodine deficiency status in the Semipalatinsk region that has been contaminated by radioactive fallout from nuclear testing during the period of the former USSR. DESIGN: Based on the Japan-Kazakstan joint project of adult cancer screening around the Semipalatinsk Nuclear Testing Site (SNTS), from May to October 2002 spot urine specimens were collected at random in each village. Separately, children aged 5-15 years from around the SNTS were chosen at random and spot urine specimens were collected from them. SETTING: Area contaminated by radioactive fallout around the SNTS, Republic of Kazakstan. SUBJECTS: A total of 2609 adults aged >40 years from 16 settlements in three regions and one city, and 298 children aged 5-15 years from two regions and one city. RESULTS: Median urinary iodine concentrations of adults and children in all regions were in the range of 116.0-381.7 and 127.7-183.0 microg l(-1), respectively. The highest prevalence of values <50 microg l(-1) (14.1%) did not exceed 20%. Distributions within each group, adults and children, showed almost the same pattern, except for one region where more than 50% of adults had urinary iodine concentration >100 microg l(-1). CONCLUSIONS: In agreement with our previous studies, the urinary iodine concentration data showed no clear evidence of iodine deficiency around the SNTS. Kazakstan is geographically and nutritionally at moderate risk of iodine deficiency disorders without fortification or iodine replacement by iodised salt. The socio-medical prophylaxis against iodine deficiency has been successfully maintained in East Kazakstan.

Adolescent↗
PubMed2005

Radon exhalation of cementitious materials made with coal fly ash: Part 2--testing hardened cement-fly ash pastes.

Increased interest in measuring radionuclides and radon concentrations in fly ash (FA), cement and other components of building products is due to the concern about health hazards of naturally occurring radioactive materials (NORM). The paper focuses on studying the influence of FA on radon exhalation rate (radon flux) from cementitious materials. In the previous part of the paper the state of the art was presented, and the experiments for testing raw materials, Portland cement and coal fly ash, were described. Since the cement and FA have the most critical role in the radon release process relative to other concrete constituents (sand and gravel), and their contribution is dominant in the overall radium content of concrete, tests were carried out on cement paste specimens with different FA contents, 0-60% by weight of the binder (cement+FA). It is found that the dosage of FA in cement paste has a limited influence on radon exhalation rate, if the hardened material is relatively dense. The radon flux of cement-FA pastes is lower than that of pure cement paste: it is about approximately 3 mBq m(-2) s(-1) for cement-FA pastes with FA content as high as 960 kg m(-3).

Air Pollutants, Radioactive↗
PubMed1987

Radon in homes. Council on Scientific Affairs.

Radon 222 and its radioactive decay products can enter buildings and, through inhalation, expose the inhabitants' pulmonary tissues to ionizing radiation. Studies of radon levels in the United States indicate that variations of 100-fold or greater exist among private dwellings. In one region, 55% of homes had levels exceeding 4 pCi/L (0.15 Bq/L), which is the guidance level recommended by the US Environmental Protection Agency. Ventilation and tightness of construction are important determinants of radon levels. In some instances, fans or heat exchangers can reduce excessive concentrations, but in others more elaborate remedial measures may be required. Physicians may obtain information about radon through Environmental Protection Agency regional offices and state radiation control programs. The risk of radiogenic cancer is believed to increase with exposure to ionizing radiation. According to some estimates, concentrations of radon decay products in US homes could be responsible for several thousand cases of lung cancer per year. Studies of radon levels in representative buildings and guidelines are needed to ensure safe, effective, and cost-effective countermeasures. Architects, contractors, designers, building code administrators, health physicists, and biomedical investigators can help with solutions.

Air Pollutants↗
PubMed2006

A new methodology for cost-effectiveness studies of domestic radon remediation programmes: quality-adjusted life-years gained within primary care trusts in central England.

Radon is a naturally occurring radioactive gas, high levels of which are associated with geological formations such as those found in Northamptonshire and North Oxfordshire in the UK. The UK's National Radiological Protection Board have designated both districts as radon Affected Areas. Radiation levels due to radon, therefore, exceed 200 Bq m(-3), the UK's domestic Action Level, in over one percent of domestic properties. Because of radon's radioactivity, exposure to the gas can potentially cause lung cancer, and has been linked to some 2000 deaths a year in the UK. Consequently, when radiation levels exceed the Action Level, remediation against radon's effects is recommended to householders. This study examines the cost-effectiveness of remediation measures in Northamptonshire and North Oxfordshire by estimating cost per quality-adjusted life-year gained in four Primary Care Trusts, organisations that play a key public health policy role in the UK's National Health Service. The study is the first to apply this approach to estimating the cost-effectiveness of radon remediation programmes. Central estimates of cost per quality-adjusted life-year in the four Primary Care Trusts range from 6143pounds to 10323pounds. These values, when assessed against generally accepted criteria, suggest the remediation programmes in the trusts were cost-effective. Policy suggestions based on the estimates, and designed to improve cost-effectiveness further, are proposed for the four Primary Care Trusts and the UK's National Health Service.

Air Pollution, Radioactive↗
PubMed2004

Analysis of a Kalman filter based method for on-line estimation of atmospheric dispersion parameters using radiation monitoring data.

A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent parameter estimates with large associated uncertainties. Improved source term assessment results, when independent estimates of the plume height can be used. Perspectives for using the method in the context of nuclear emergency management are discussed, and possible extensions to the present modelling scheme are outlined, to account for realistic accident scenarios.

Air Pollutants, Radioactive↗
PubMed1993

Estimating past exposure to indoor radon from household glass.

CR-39 plastic was attached to household glass objects to learn whether residual radioactivity from radon decay products could be measured and correlated with cumulative radon exposures over defined time periods. Such an approach could be used to increase the completeness of exposure data collected in epidemiologic studies of residential radon. Inability to estimate radon concentrations for all residences adversely effects statistical power and thus the ability to detect an effect of radon exposure on lung cancer risk. A feasibility study was performed to determine if affixing CR-39 surface monitors to selected glass, ceramic, or enameled objects provided comparable estimates of past residential radon exposure to those obtained from year-long ambient alpha track-etch measurements. The CR-39 measurements of alpha activity in the surface of selected objects correlated with ambient radon measurements (R2 = 0.48) provided that reliable information was obtained on the history and age of the objects. This technique has now been incorporated into an epidemiologic study of radon and lung cancer to more fully estimate past exposure to indoor radon.

Air Pollution, Indoor↗
PubMed1997

Radon: a human carcinogen.

Radon is a naturally occurring, radioactive gas that is found in Group 0 of the periodic table. Normally, it is found in extremely low levels in air but can, in certain geological formations, be a significant component of soil gas. Doses from radon are the largest component of the average radiation exposure for the UK general population. Certain areas, e.g. Cornwall, of the UK have been found to have elevated levels of radon in dwellings and these have been classified as Affected Areas. Here authorities can declare that radon prevention measures are needed in new houses and that existing houses with high levels should be identified and remedied. In radon Affected Areas, individuals, in homes and the workplace, can be receiving high doses of radiation. There is overwhelming evidence that exposure to radon, at the levels found in mines, leads to lung cancer. But what happens when individuals are exposed to the lower levels found in homes and the majority of workplaces? There is clear biological evidence for the role of radon inducing lung cancer and the epidemiological evidence is now beginning to emerge. The population at large needs to act. When high levels are found in buildings, prompt action needs to be taken to reduce levels via proven technology.

Air Pollutants, Radioactive↗
PubMed1986

Distribution of airborne radon-222 concentrations in U.S. homes.

Apparently large exposures of the general public to the radioactive decay products of radon-222 present in indoor air have led to systematical appraisal of monitoring data from U.S. single-family homes; several ways of aggregating data were used that take into account differences in sample selection and season of measurements. The resulting distribution of annual-average radon-222 concentrations can be characterized by an arithmetic mean of 1.5 picocurie per liter (55 becquerels per cubic meter) and a long tail with 1 to 3% of homes exceeding 8 picocuries per liter, or by a geometric mean of 0.9 picocurie per liter and a geometric standard deviation of about 2.8. The standard deviation in the means is 15%, estimated from the number and variability of the available data sets, but the total uncertainty is larger because these data may not be representative. Available dose-response data suggest that an average of 1.5 picocuries per liter contributes about 0.3% lifetime risk of lung cancer and that, in the million homes with the highest concentrations, where annual exposures approximate or exceed those received by underground uranium miners, long-term occupants suffer an added lifetime risk of at least 2%, reaching extraordinary values at the highest concentrations observed.

Air Pollutants↗
PubMed1996

[The genetic sequelae of the Chelyabinsk and Chernobyl radioactive contaminations].

Genetic consequences of radioactive fall-outs of the Chelyabinsk plant producing plutonium (1949-1952) and the Chernobyl accident have been analysed. Three powerful radioactive fall-outs caused a population genetic dose of 682,801 cSv per 217,750 persons (the average dose was 2.25 cSv). Individual variations were from 1-2 mSv to 1.2 Sv or more. The population genetic dose from the Chernobyl accident was higher (32 x 10(6) man/cSv), but the individual dose was lower (mainly no more than 1 cSv). Progenic analyses of residents of radiation contaminated areas showed no increase in the incidence of congenital anomalies, spontaneous abortions, developmental microanomalies, and Down syndromes (except Byelorussia). Calculations of genetic consequences for the Ural region demonstrated that only in the most contaminated area (the average gonadal dose was 19.5 cSv); a 4.13% increase of the spontaneous level could be observed. In all other areas it was less than 1%. It is difficult to reveal possible genetic consequences of the Chernobyl accident using the real sample size of the newborns. Even in the areas with fall-outs above 15 Ci/km2, the incidence of congenital anomalies did not exceed 1% of the spontaneous level.

Abnormalities, Radiation-Induced↗
PubMed1996

Overview of the Fernald Dosimetry Reconstruction Project and source term estimates for 1951-1988.

The Feed Materials Production Center, northwest of Cincinnati, processed uranium concentrates and uranium compounds recycled from other stages of nuclear weapons production, as well as some uranium ore and thorium. Particulate releases were primarily uranium (natural, depleted, and slightly enriched. In addition, two large silos containing radium-bearing residues were emission sources of radon and its decay products. The Fernald Dosimetry Reconstruction Project was undertaken to help the Centers for Disease Control and Prevention to evaluate the impact of the Feed Materials Production Center on the public from radionuclides released to the environment from 1951 through 1988. At this point in the study, the project has estimated the quantities of radioactive materials released to air, surface water, and in groundwater; developed the methodology to describe the environmental transport of the materials; developed mathematical models to calculate the resulting radiation doses; and evaluated environmental monitoring data to verify that the estimates of releases and transport are reasonable. Thorough review of historical records and extensive interaction with former and current employees and residents have been the foundation for reconstructing routine operations, documenting accidents, and evaluating unmonitored emission sources. The largest releases of uranium to air and water occurred in the 1950's and 1960's. Radon releases from the silos remained elevated through most of the 1970's. The quantity of uranium released to surface water was much less than that released to air. Best estimates of releases are reported as median values, with associated uncertainties calculated as an integral part of the estimates. Screening calculations showed that atmospheric pathways dominate the total dose from Feed Materials Production Center releases. Accordingly, the local meteorology, effluent particle size and chemical form, and wet and dry deposition, were particularly important in this study. The final goal of the project is the calculation of radiation doses to people living in the study domain, which is represented by a circle with radius of 10 km centered on the Feed Materials Production Center production area.

Air Pollutants, Radioactive↗
PubMed2006

A novel technique for the rapid identification of alpha emitters released during a radiological incident.

Before the May 2003 TOPOFF II exercise in Seattle, the U.S. EPA's Laboratory in Las Vegas prepared five spiked samples to be analyzed by the Washington State Department of Health's (WSDOH) Radiation Laboratory. Two of these were simulated deposition samples prepared on packaging tape. Laboratories throughout the world are investigating rapid methods for analyzing plume-borne radioactive materials. While measuring gamma emitters in environmental samples is fairly straightforward, the potential presence of alpha emitters adds complexity. The short range of alpha particles and the high degree of energy interference between nuclides usually require chemical separations and very thin mounts for alpha spectrometry. Work published on Frisch-Grid alpha counting of transuranics in soil and the commercial development of radon-rejection for air filters indicate that alpha spectrometry can be used directly on some media with success. This suggests that plume-borne material sampled from air or freshly deposited surface layers may be counted directly by alpha spectrometry, making it possible to identify both alpha and gamma emitters and determine their relative concentrations. The long-range objective is to propose a sampling method that can be used for rapid qualitative and semi-quantitative analyses using conventional radioanalytical instruments, with minimal preparation. This paper describes experimentation with this approach during a real-time exercise. All samples were prepared by spiking with (137)Cs, (241)Am, (238)Pu, and (239)Pu and presented to the WSDOH's Radiation Laboratory for analysis during TOPOFF II. The laboratory quickly identified and determined the ratios of all four contaminants on the tape samples using sequential alpha spectrometry and gamma-ray spectroscopy without chemical separations.

Air Pollutants, Radioactive↗