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PubMed2001

Radioactivity in tobacco leaves.

The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to find any association between the uptake of the naturally occurring radionuclides and the isotopes of cesium of Chernobyl origin. The activities of the isotopes of radium, 226Ra and 228Ra, in the tobacco leaves reflected their origin from the soil by root uptake rather than from fertilizers used in the tobacco cultivation. Lead-210 originated from the air and was deposited onto the tobacco leaves and trapped by the trichomes. Potassium-40 in the tobacco leaves was due to root uptake either from soil or from fertilizer. The isotopes of cesium, 137Cs and 134Cs, in the tobacco leaves were due to root uptake and not due to deposition onto the leaf foliage as they still remained in soil four years after the Chernobyl reactor accident but were absent from the atmosphere in rain washout (precipitation) and gravitational settling.

Air Pollutants, Radioactive↗
PubMed1975

Environmental Radioactivity in Denmark in 1974.

The present report deals with the measurement of fall-out radioactivity in Denmark in 1974. Strontium-90 was determined in samples from all over the country of precipitation, soil, ground water, sea water, grass, dried milk, fresh milk, grain, bread, potatoes, vegetables, fruit, total diet, drinking water, and human bone. Furthermore, 90Sr was determined in local samples of air, rain water, grass, sea plants, fish, and meat. Caesium-137 was determined in soil, sea water, milk, grain products, potatoes, vegetables, fruit, total diet, fish, and meat. It was also measured by wholebody-counting of a control group at Tisø. Estimates of the mean contents of radiostrontium and radiocaesium in the human diet in Denmark during 1974 are given. The gamma-background was measured regularly at locations around Risø, at ten of the State experimental farms, in one area in Zealand, one in Jutland, and along the shores of the Great Belt. Finally the report includes routine surveys of environmental samples from the Risø area.

Air Pollution, Radioactive↗
PubMed2006

Distribution of doses received by Cuban population due to environmental sources of radioactivity.

Doses received by Cuban population due to exposure to the environmental sources of radiation were studied for their evaluation. Estimations of doses from the different components of the total dose were obtained and published. From the results obtained estimations of total doses to Cuban population from environmental radiation sources and the contributions of different dose components were made. A Monte Carlo simulation of the sum of doses was carried out and the distribution of obtained values was assumed as a lognormal distribution. Parameters for characterisation of this lognormal distribution were estimated, and on the basis of the estimations the average total effective dose to the Cuban population owing to exposure to the environmental sources was estimated as 1.1 +/- 0.3 mSv y(-1). This low dose value is in the range of doses estimated by UNSCEAR for world population due to natural background and can be explained by the specifics of the Cuban environment.

Air Pollutants, Radioactive↗
PubMed1999

Calculation of airborne radioactivity in a Technegas lung ventilation unit.

Airborne contamination by 99Tcm has been monitored in the Nuclear Medicine Department in our hospital to assess the risk of internal contamination to occupational workers exposed to Technegas studies. An air sampler fitted with a membrane filter was used. The optimum time for air absorption for obtaining the maximum activity in the filter was calculated. Maximum activity in the membrane filter ensures minimum uncertainty, which is especially important when low-level activities are being measured. The optimum time depends on air absorption velocity, room volume and filter efficiency for isotope collection. It tends to 1/lambda (lambda = disintegration constant for 99Tcm) for large volume and low velocity. Room activity with the air pump switched on was related to filter activity, and its variation with time was studied. Free activity in air for each study was approximately 7 x 10(-4) the activity used, and the effective half-life of the isotope in the room was 13.9 min (decay and diffusion). For a typical study (630 MBq), the effective dose to staff was 0.01 microSv when in the room for 10 min.

Air Pollutants, Radioactive↗
PubMed1989

Acute effects of the Chernobyl nuclear accident on Irish mortality?

This report examines the claim that Irish mortality in the second quarter (April-June) of 1986 increased due to the cloud of radioactive material released by the damaged reactor in Chernobyl. Over the period 1971-1987, based on date of registration, the death rates in the second quarter showed marked year to year variation often exceeding that expected on the basis of chance alone. In 1986 the percentage of annual deaths occurring between April and June, and the death rate itself, were both significantly higher than in most other years between 1981 and 1987. The 1986 figures were not however, significantly higher than those observed in years prior to 1981. Since the distribution of mortality by cause was not consistent with the hypothesis relating low level radiation to immediate mortality, and since causality cannot be inferred from a temporal association per se, the Chernobyl accident cannot be implicated in the excess mortality observed in the second quarter of 1986.

Accidents↗
PubMed1987

[Radioactivity levels of the air inhaled by personnel of a radioiodine therapy unit].

The mean activity concentration of 131I during inhalation by the nuclear medicine personnel was measured at therapeutic activity applications of 22 GBq (600 mCi) per week. The activity concentration reached its maximum in the exhaled air of the patients 2.5 to 4 hours after oral application. The normalized maximum was between 2 X 10(-5) and 2 X 10(-3) Bq X m-3 per administered Bq. The mean activity concentration of 131I inhaled by the personnel was 28 to 1300 Bq X m-3 (0.8 to 35 nCi X m-3). From this the 131I uptake per year was estimated to be 30 to 400 kBq/a (mean = 250, SD = 50%). The maximum permitted uptake from air per year is, according to the German and Austrian radiation protection ordinances 22/21 microCi/a (= 8 X 10(5) Bq/a). At maximum 50% and, on the average, 30% of this threshold value are reached. The length of stay of the personnel in the patient rooms is already now limited to such an extent that 10% of the maximum permissible whole-body dose for external radiation is not exceeded. Therefore, increased attention should be paid also to radiation exposure by inhalation.

Air Pollution, Radioactive↗
PubMed1994

[Discrepancies in assessment of radiological exposure level in miners related to the use of various measurement systems].

The contamination of the air with radioactive elements (radon-222 and its decay products) occurs in coal, metal ore and chemical raw materials underground mines. This causes irradiation of the miner's respiratory system with ionizing radiation. In Poland the radiation exposure level is controlled both by the ventilation services of particular mines and by the Nofer Institute of Occupational Medicine in Lodz to the order of the State Sanitary Inspection. The in-mine services collect air samples which are next examined to determine the degree of radiation contamination (environmental monitoring), whereas the Institute uses the method of representative individual dosimetry (the dosimeters are attached to the miners' helmets). The article presents discrepancies in the levels of exposure to radiation in mines, assessed by the in-mine services and the Nofer Institute of Occupational Medicine. The hazard level determined by these services is usually one or even two times lower than that determined by the Institute. The reasons for these discrepancies are discussed.

Air Pollutants, Radioactive↗
PubMed2005

Use of alpha spectroscopy for conducting rapid surveys of transuranic activity on air sample filters and smears.

This paper demonstrates the utility of a portable alpha Continuous Air Monitor (CAM) as a bench top scalar counter for multiple sample types. These include using the CAM to count fixed air sample filters and radiological smears. In counting radiological smears, the CAM is used very much like a gas flow proportional counter (GFPC), albeit with a lower efficiency. Due to the typically low background in this configuration, the minimum detectable activity for a 5-min count should be in the range of about 10 dpm which is acceptably below the 20 dpm limit for transuranic isotopes. When counting fixed air sample filters, the CAM algorithm along with other measurable characteristics can be used to identify and quantify the presence of transuranic isotopes in the samples. When the radiological control technician wants to take some credit from naturally occurring radioactive material contributions due to radon progeny producing higher energy peaks (as in the case with a fixed air sample filter), then more elaborate techniques are required. The techniques presented here will generate a decision level of about 43 dpm for such applications. The calibration for this application should alternatively be done using the default values of channels 92-126 for region of interest 1. This can be done within 10 to 15 min resulting in a method to rapidly evaluate air filters for transuranic activity. When compared to the 1-h count technique described by , the technique presented in the present work demonstrates a technique whereby more than two thirds of samples can be rapidly shown (within 10 to 15 min) to be within regulatory compliant limits. In both cases, however, spectral quality checks are required to insure sample self attenuation is not a significant bias in the activity estimates. This will allow the same level of confidence when using these techniques for activity quantification as is presently available for air monitoring activity quantification using CAMs.

Air Pollutants, Radioactive↗
PubMed1995

Biokinetics of nuclear fuel compounds and biological effects of nonuniform radiation.

Environmental releases of insoluble nuclear fuel compounds may occur at nuclear power plants during normal operation, after nuclear power plant accidents, and as a consequence of nuclear weapons testing. For example, the Chernobyl fallout contained extensive amounts of pulverized nuclear fuel composed of uranium and its nonvolatile fission products. The effects of these highly radioactive particles, also called hot particles, on humans are not well known due to lack of reliable data on the extent of the exposure. However, the biokinetics and biological effects of nuclear fuel compounds have been investigated in a number of experimental studies using various cellular systems and laboratory animals. In this article, we review the biokinetic properties and effects of insoluble nuclear fuel compounds, with special reference to UO2, PuO2, and nonvolatile, long-lived beta-emitters Zr, Nb, Ru, and Ce. First, the data on hot particles, including sources, dosimetry, and human exposure are discussed. Second, the biokinetics of insoluble nuclear fuel compounds in the gastrointestinal tract and respiratory tract are reviewed. Finally, short- and long-term biological effects of nonuniform alpha- and beta-irradiation on the gastrointestinal tract, lungs, and skin are discussed.

Air Pollutants, Radioactive↗
PubMed1987

Surface radioactivity resulting from the deposition of 222Rn daughter products.

Studies of indoor radiation environments typically involve measurements of 222Rn, airborne 222Rn decay products, and the degree of radioactive equilibrium. This paper describes the relationship between the 222Rn in air, and the level of surface radioactivity that results from the build-up and decay of the daughter isotope, 210Pb. Samples of 222Rn were collected from Mystery Cave, which is located in southeastern Minnesota and from the basement of a house in Minneapolis, MN. Lead-210 was measured on surfaces within the cave, on a rock removed from the cave, and on a basement window. Surface alpha activities were measured on the rock sample and on the window. Radon-222 concentrations in the cave air ranged from 3 to 13 kBq m-3. In the basement, 222Rn levels were between 0.2 and 0.4 kBq m-3. Virtually all the surface radioactivity resulted from the deposition and decay of airborne 222Rn daughter products and was not produced by the decay of U in the rock. Radon-222 concentrations in the cave air were almost 30 times higher than in the basement air; however, the surface 210Pb activity in the cave was 100 times higher than that in the basement. This suggests that in the cave air, 222Rn daughter products are more likely to reach the walls and decay to 210Pb. The measurements of surface alpha activity did not show a similar trend primarily because 210Pb had diffused further into the coating of dirt on the rock than into the glass of the window. The resulting surface activity of the rock was lower than expected based on the 210Pb concentration, because many of the alpha-emitting nuclei were at depths beyond the range of emitted alpha particles. On surfaces where the penetration range of alpha particles is greater than the diffusion depth of 210Pb atoms, either the 210Pb concentration or surface alpha-activity measurements should provide estimates of average long-term 222Rn concentrations.

Air Pollutants↗
PubMed2001

Improvements in modeling sagebrush concentrations of radioiodine released from the Hanford site.

The Hanford Environmental Dose Reconstruction Project estimated the radiation dose to individuals from historical emissions of radioactive materials from the Hanford Site in Washington State. Project validation studies using predicted activity concentrations of 131I on sagebrush (Artemisia tridentata) showed a systematic underestimation against historical data during cold weather months, indicating a need for sagebrush model improvement. A deposition model for semi-volatile organic materials presented by Komp and McLachlen (Environ. Sci. Tech. 31 (1997) 886-890) is adapted here for gaseous iodine onto sagebrush. The deposition model includes a temperature-dependent term based on an integrated van't Hoff equation. Calibration data for the model are obtained from a release of 131I in 1963. Modeling results for releases in 1946 show a good match between historical data and predicted results using the new model. The new model shows improvement over interception-fraction type models, but requires plant-type-specific calibration data.

Air Pollution, Radioactive↗
PubMed2007

Chlorine-39 in rainfall at a temperate latitude (40 degrees N).

Rainwater samples were collected and measured for the radioactivity to confirm the presence of Chlorine-39 (T1/2=56.2 min) formed by the interaction of cosmic-ray slow negative muons, mu- with Argon-40 in the lower atmosphere. The presence of 39Cl was confirmed by estimating the half-life of a radionuclide present in the rainwater ranging from 58 to 63 min and averaging 60.4 min. The disintegration rate of this radionuclide varied from 2.1 to 2.7 Bq L(-1) (125-160 dpm/L) of rainwater and averaged 2.3 Bq L(-1) (140 dpm/L) of rainwater in Thessaloniki (40 degrees 38'N, 22 degrees 58'E), Northern Greece. This concentration is indicative of mid or temperate latitudes. This is clearly less than that reported in the literature, 1.7 Bq L(-1) (100 dpm/L) of rainwater, for a southern latitude 31 degrees 54'N, 34 degrees 49'E (Rehovot, Israel), due to the latitudinal effect of cosmic radiation.

Air Pollutants, Radioactive↗
PubMed2005

Investigation of occupational radiation exposures to NORM at an Irish peat-fired power station and potential use of peat fly ash by the construction industry.

Annually, approximately 15% of Ireland's electricity requirement is provided through the combustion of 3 x 10(6) tonnes of peat. While the literature on coal-fired power generation is quite abundant, studies on the peat-fired power generation industry from a radiological point of view are scarce. A study of the largest Irish peat-fired power plant was initiated to review the potential occupational radiation exposures arising from the occurrence of naturally occurring radioactive material (NORM) at different stages of the industrial process and to investigate any radiological health consequences that may arise should peat fly ash be used as a component of building materials. Ambient gamma dose rate measurements, radon measurements, quantification of the occupational exposure from inhalation of airborne particles (personal air sampling) and gamma spectrometry analysis of peat, peat ash and effluent samples from the ash ponds were undertaken. The results indicate that the radiation dose received by any worker involved in the processing of the peat and the handling of the ash resulting from peat combustion does not exceed 150 microSv per annum. Regulatory control of the peat-fired power generation is therefore unnecessary according to the Irish legislation with regards to NORM. The potential use of peat fly ash as a by-product in the building industry was also found to have a negligible radiological impact for construction workers and for members of the public.

Air Pollutants, Radioactive↗
PubMed2006

Modelling radon progeny concentration variations in thermal spas.

Radon and its short-lived progenies (218Po, 214Pb, 214Bi and 214Po) are well known radioactive indoor pollutants identified as the major radiation burden component of the thermal spa users. Monitoring of short-lived progeny concentration is of great importance for short-term dose estimations both for bathers and working personnel. A prediction model of the short-lived progeny concentration variations was developed and applied on published data of the thermal spas of Lesvos Island. The physical procedures involved were modeled in a set of differential equations describing radon progeny concentration variations on the basis of radon measurements. Published daughter data were fitted on model predictions adjusting non-measured parameters, e.g. attachment and deposition rate constants for attached and unattached progenies. Attachment rate constants were estimated between 50 and 200 h-1 while the deposition rate constants between 0.25 and 5 h-1 for attached progenies and 0.5 and 170 h-1 for the unattached ones. In addition, unattached 218Po, 214Pb and 214Bi progenies were found to be shifted forward in respect to radon approximately 0.001 h, 0.05 h and 0.40 h respectively, while attached 218Po, 214Pb and 214Bi progenies 0.05 h, 0.45 h and 0.65 h respectively.

Air Pollutants, Radioactive↗
PubMed1988

Deposition and retention patterns for 3-, 9-, and 15-micron latex microspheres inhaled by rats and guinea pigs.

This study was designed to determine the deposition patterns and fate of large particles inhaled by two species of small laboratory animals during nose breathing. Rats and guinea pigs inhaled 3-, 9-, or 15 micron polystyrene latex microspheres labeled with 46Sc. Approximately 1.4% and 0.55% of the initial internally deposited body burden of 3-micron microspheres was in the alveolar region of the respiratory tract of rats and guinea pigs, respectively. None of the 9- or 15-micron microspheres were detected in the alveolar regions of the rats or guinea pigs. Ninety-five to 99% of the deposited microspheres cleared from these animals with biological half-times of 0.5-1.0 day. Most of the cleared radioactivity was in the feces. Approximations for long-term biological half-times for alveolar retention of the 3-micron microspheres were 63 days for rats and 83 days for guinea pigs. About 1% of the initial lung burden of 3-micron microspheres was translocated from lung to lung-associated lymph nodes in both species; none of the 9- or 15-micron microspheres were detected in those lymph nodes. Small fractions of the microspheres initially deposited in the airways of the head were retained with biological clearance half-times ranging from 9 to 350 days. Results from this study do not allow projections for deposition and retention patterns for similar particles inhaled by humans. Such projections must come from studies with humans, or from studies with animal species having deposition patterns for inhaled materials more comparable to those of humans.

Air Pollutants↗
PubMed1971

Analysis of a case of internal contamination with 242Cm.

During the preparation of targets for the mass spectrometer some 242Cm escaped from the preparation box resulting in a contamination of the laboratory air and of subsequent ingestion of radioactivity by the technician concerned. Nose wipe tests were taken immediately after the incident and faecal and urine samples during the following week. Air sampling filters located in three places in the laboratory were changed immediately and then at regular intervals. The size distribution of the particles was calculated from autoradiographs made from the filter samples. From the results of these analyses the quantity ingested in the respiratory tract was determined using the ICRP "Lung Model" as a guide. The distribution of the ingested material in the body organs was then estimated from the data in Publication 2 (1959) of the ICRP. Although the quantities involved predicted an internal contamination far below the maximum permissible values, this detailed analysis was carried out as an opportunity for testing the "Lung Model" in the case of Curium inhalation. Interpretation and comparison of air filter sampling data with results of nose wipe and faecal tests suggest that the ICRP lung model may serve as a useful guide to estimate the approximate level of an internal contamination after inhalation exposure to 242Cm.

Accidents, Occupational↗
PubMed1999

Enhanced airborne radioactivity during a pine pollen release episode.

A single episode of pine pollen release in the highly contaminated area of Novozybkov, Russian Federation, which led to enhanced atmospheric concentrations of 137Cs is discussed. The pollen grains were sampled by a rotating arm impactor and analysed by gamma-spectrometry for 137Cs activity and by image analysis for their size. In the vicinity of a forest, a maximum concentration of 4.5+/-0.4 mBq m(-3) was measured, and a mean activity per pollen grain of 260+/-80 nBq was determined. The emission rate of the Novozybkov mixed pine forest was estimated to be approximately 400 Bq m(-2) per year. Because of the large size of pine pollen grains (about 50 microm) and the short emission period of 5-8 days per year, the estimated potential annual inhalation doses are very low. Biological emissions including pollen release may be a source of increased airborne radionuclide concentrations at larger distances from the source areas as well.

Accidents↗
PubMed1986

Determination of particle size for airborne UO2 dust at a fuel fabrication work station and its implication on the derivation and use of ICRP Publication 30 derived air concentration values.

When internal radiation exposure occurs via the inhalation route, the activity deposition in the respiratory tract is dependent on the particle size distribution of the radioactive aerosol. This fact has been recognized by ICRP Publication 30 in which annual limit of intake (ALI) and derived air concentration (DAC) values have been calculated for a variety of radionuclides based upon an activity median aerodynamic diameter (AMAD) of 1 micron. When radioactive aerosols have AMADs not equal to 1 micron, ICRP Publication 30 suggests the use of correction factors to calculate the appropriate ALI and DAC values. This work describes the measurement of particle size distribution for UO2 dust at a fuel fabrication work station by means of a cascade impactor. Measurements were made on 39 d spread over a 10-mo period to determine if the particle size distribution was stable over a year. The results of this study indicate that for this work station the measured AMAD values are not stable over a year. A discussion is provided on the treatment of such particle-size distribution data with the objective of extracting a representative particle-size distribution value, upon which an ALI and a DAC value can be determined. The observations made in this study have implications on the application of ICRP Publication 30 recommendations to operational health physics practice.

Air Pollutants↗