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PubMed2006

A new digital autoradiographical method for identification of Pu particles using an imaging plate.

An autoradiographical method using an imaging plate (IP) was developed to identify rapidly the density of plutonium (Pu) particles on filter samples. Photostimulated luminescence (PSL) signals were obtained by exposing IPs to filter samples collecting Pu particles and naturally occurring radon decay products, respectively. Search and analysis of the alpha-induced PSL signals presented the time-dependent growth of PSL intensity from the Pu particles and the range of PSL intensities from radon decay products, making it possible to discriminate Pu particles from radon decay products using an empirical Pu-discrimination level, and then to quantify the Pu activities on a particle-by-particle basis. The method is useful for a fast screening of filter samples for Pu particles because it requires no special skills and tedious procedures during its use, gives a low discriminable activity for individual Pu particles with a relatively short exposure time, and allows us to measure a large number of filter samples at the same time.

Air Pollutants, Radioactive↗

PubMed2006

Determination of 210Po in environmental materials: a review of analytical methodology.

Polonium-210 ((210)Po) is analysed for a variety of purposes, including for radiological impact assessment, as a tracer of environmental processes, and as an indirect measure of its progenitor lead-210 ((210)Pb). Losses of polonium may occur at temperatures above 100 degrees C, depending on conditions, requiring particular care in sample preparation and treatment. In spite of this problem, the analysis of (210)Po is relatively straightforward, due to the ease of source preparation through spontaneous auto-deposition onto metal surfaces and the uncomplicated alpha spectrum. Although several optimisation studies have been carried out, published source preparation methods remain remarkably diverse. Some areas where further study would be useful are identified.

Air Pollutants, Radioactive↗

PubMed2006

Indoor 222Rn survey in Zacatecas State, Mexico.

As part of a program for discovering whether afflicted areas exist, indoor (222)Rn concentrations in the State of Zacatecas were surveyed, (222)Rn concentration being measured by gamma-ray spectrometry of radon decay products adsorbed into charcoal canisters. A survey was implemented during Summer 2001: 228 dwellings in the state were tested by taking mean 254 measurements. Concentrations exhibited a left-skewed distribution of indoor (222)Rn, showing overall average, minimum, and maximum concentrations of 67, 26, and 511 Bqm(-3), respectively. Only seven of the measurements (2.7%) were found equal to or greater than the US EPA action limit (148 Bqm(-3)). Thus, we conclude that the indoor radon environment in Zacatecas State is under US EPA action limit. The few high concentration spots suggest that geological conditions rather than construction materials may be the determinant factor.

Air Pollution, Indoor↗

PubMed2005

Retrospective birth dating of cells in humans.

The generation of cells in the human body has been difficult to study, and our understanding of cell turnover is limited. Testing of nuclear weapons resulted in a dramatic global increase in the levels of the isotope 14C in the atmosphere, followed by an exponential decrease after 1963. We show that the level of 14C in genomic DNA closely parallels atmospheric levels and can be used to establish the time point when the DNA was synthesized and cells were born. We use this strategy to determine the age of cells in the cortex of the adult human brain and show that whereas nonneuronal cells are exchanged, occipital neurons are as old as the individual, supporting the view that postnatal neurogenesis does not take place in this region. Retrospective birth dating is a generally applicable strategy that can be used to measure cell turnover in man under physiological and pathological conditions.

Adult↗

PubMed2005

Archeo-cell biology: carbon dating is not just for pots and dinosaurs.

Defining the life span of specific human cell populations is limited by our inability to mark the exact time when cells are born in a way that can be detected over many years. In this issue of Cell, Spalding et al. (2005) describe a clever strategy for retrospectively birth dating human cells in vivo, based on their incorporation of 14C during a peak in atmospheric levels of this isotope resulting from above-ground nuclear arms testing in the 1950s.

Air Pollution, Radioactive↗

PubMed2004

A physiologically based assessment of human exposure to radon released from groundwater.

Most of the indoor radon comes directly from the soil beneath the foundation of a basement. Recently, radon from groundwater was found to make some contribution to the total inhalation risk associated with radon in indoor air. This study presents a realistic exposure assessment of a human to indoor radon released from groundwater. First, the prediction of indoor radon concentration released from groundwater was based on a three-compartment model that was developed to describe the transfer and distribution of the radon released from groundwater in a house through showers, washing clothes, and flushing toilets. Second, a physiologically based pharmacokinetic (PBPK) model for inhaled radon was developed and used to estimate tissue group concentrations in a human body. The PBPK model provides reasonable predictions of uptake, excretion, and distribution of retained radon among tissue groups in the body. Hence, the approach using the PBPK model combined with realistic indoor exposure scenarios predicts the radon concentrations in tissue groups in the body associated with the indoor radon pollution. The results obtained from the study will help increase the quantitative understanding of the risk assessment issues associated with the indoor radon released from the groundwater.

Air Pollutants, Radioactive↗

PubMed2006

Epidemiology and outcomes research for MGUS, myeloma and amyloidosis.

The epidemiology of plasma cell dyscrasias clearly links to a complicated multi-factorial pathogenic pathway that at the individual patient level gives no clear indication of why the malignant process has occurred but factors in the environment and within the genome give clues and are discussed. MGUS is a pre-malignant disorder characterised by monoclonal plasma cell proliferation in the bone marrow and no end-organ damage; the patients are asymptomatic. Primary amyloidosis is a rare disorder that is characterised by deposition of amyloid fibrils composed of immunoglobulin light chain fragments; symptoms relate to the affected organ. Multiple myeloma is a malignant disease of plasma cells and with improvements in treatment, patients can now expect a doubling of median survival to 5 years, a 20% chance of surviving >10 years and a 50% chance of complete remission (CR), morphological and biochemical. The challenge is now to determine exactly what this means to the individual myeloma patient in terms of benefit, and to society as a whole and this is the basis of 'outcomes research' which is discussed in this review.

Age Distribution↗

PubMed2005

Critical analysis of radiochemical methodologies for the assessment of sediment pollution and dynamics in the lagoon of Venice (Italy).

Aquatic sediments are the ultimate sink of wastes dispersed in freshwater and soil. They are therefore a useful tool for investigating polluted ecosystems. Lagoon environments are very difficult to study due to their unstable morphology. Under these circumstances, even an excellent environmental investigation of a restricted lagoon area would still be inadequate to appreciate the characteristics of the entire system. The Venice lagoon is a very complex ecosystem whose morphology is complicated further by extensive anthropic intervention. A good environmental representation of the area was obtained with a preliminary radiochemical survey of airborne radionuclides, a unique tool in evaluating the homogeneity of the entire sedimentary system. It must be stressed, however, that the significance of the data depends substantially on the use of qualified procedures. Based on this, a detailed study was carried out on selected homogeneous areas, reconstructing the inventories and fluxes of pollutants in the sediments. In this work the radiochemical approach to the environmental study of the Venice lagoon is examined.

Air Pollutants, Radioactive↗

PubMed2006

The value of Seasonal Correction Factors in assessing the health risk from domestic radon: a case study in Northamptonshire, UK.

Following an intensive survey of domestic radon levels in the United Kingdom (UK), the former National Radiological Protection Board (NRPB), now the Radiation Protection Division of the Health Protection Agency (HPA-RPD), established a measurement protocol and promulgated Seasonal Correction Factors applicable to the country as a whole. Radon levels in the domestic built environment are assumed to vary systematically and repeatably during the year, being generally higher in winter. The Seasonal Correction Factors therefore comprise a series of numerical multipliers, which convert a 1-month or 3-month radon concentration measurement, commencing in any month of the year, to an effective annual mean radon concentration. In a recent project undertaken to assess the utility of short-term exposures in quantifying domestic radon levels, a comparative assessment of a number of integrating detector types was undertaken, with radon levels in 34 houses on common geology monitored over a 12-month period using dose-integrating track-etch detectors exposed in pairs (one upstairs, one downstairs) at 1-month and 3-month resolution. Seasonal variability of radon concentrations departed significantly from that expected on the basis of the HPA-RPD Seasonal Correction Factor set, with year-end discontinuities at both 1-month and 3-month measurement resolutions. Following this study, monitoring with electrets was continued in four properties, with weekly radon concentration data now available for a total duration in excess of three and a half years. Analysis of this data has permitted the derivation of reliable local Seasonal Correction Factors. Overall, these are significantly lower than those recommended by HPA-RPD, but are comparable with other results from the UK and from abroad, particularly those that recognise geological diversity and are consequently prepared on a regional rather than a national basis. This finding calls into question the validity of using nationally aggregated Seasonal Correction Factors, especially for shorter exposures, and the universal applicability of these corrections is discussed in detail.

Air Pollution, Indoor↗

PubMed2005

Uptake of radionuclides by vegetation at a High Arctic location.

Radionuclide levels in vegetation from a High Arctic location were studied and compared to in situ soil concentrations. Levels of the anthropogenic radionuclide 137Cs and the natural radionuclides 40K, 238U, 226Ra and 232Th are discussed and transfer factor (TF) values and aggregated transfer (Tag) values are calculated for vascular plants. Levels of 137Cs in vegetation generally followed the order mosses > lichen > vascular plants. The uptake of 137Cs in vascular plants showed an inverse relationship with the uptake of 40K, with 137Cs TF and Tag values generally higher than 40K TF and Tag values. 40K activity concentrations in all vegetation showed little correlation to associated soil concentrations, while the uptake of 238U, 226Ra and 232Th by vascular and non-vascular plants was generally low.

Air Pollutants, Radioactive↗

PubMed2005

Radionuclides, heavy metals and fluorine incidence at Tapira phosphate rocks, Brazil, and their industrial (by) products.

Inorganic phosphate fertilizers may contain radionuclides, heavy metals and fluorine. This paper presents the possible environmental hazards from Tapira phosphate rocks and their (by) products (Brazil) utilized as phosphate fertilizers. The activity concentration of 238U, 234U, 226Ra and 40K in Tapira phosphate rocks is within the world range for these rock types. The 232Th activity concentration is higher than the mean reported in phosphate rocks. A value of 2184 nGy h(-1) was obtained for the exposure dose rate in Tapira phosphate deposit area, which is indicative of a high background radiation area. The flotation-separation process causes the incorporation of no more than 9%, 11% and 24% of radionuclides, heavy metals and fluorine, respectively, into the phosphate concentrate. The radionuclides and heavy metals existing in phosphate fertilizers applied in Brazilian crops according to the recommended rates, do not raise their concentration in soils to harmful levels.

Air Pollutants, Radioactive↗

PubMed2005

Measurements of environmental terrestrial gamma radiation dose rate in three mountainous locations in the western region of Saudi Arabia.

This paper describes measurements of external gamma radiation dose rate from terrestrial gamma-rays 1m above the ground in three different mountainous locations in the western region of the Kingdom of Saudi Arabia. These locations are At-Taif city, Al-Hada village, and Ash-Shafa village. CaSO4:Dy (TLD-900) thermoluminescent dosimeters were used for the detection of terrestrial gamma radiation at 40 different places in the three locations. The values of terrestrial gamma radiation dose rate measured ranged between 14 and 279 nGy h(-1) for the time interval from June 2001 to June 2002. The measured dose rate varied with the season of the year. The average gamma radiation dose rates were 468, 541, and 781 microGy y(-1) for At-Taif city, Al-Hada village, and Ash-Shafa village, respectively. The corresponding average absorbed doses to the population of the three locations were 328, 379, and 547 microSv y(-1), respectively. The quality factor of 0.7 SvG y(-1) was applied in the calculations of the absorbed dose to humans.

Air Pollutants, Radioactive↗

PubMed2004

Loss of heterozygosity on chromosome 9q22.3 in microdissected basal cell carcinomas around the Semipalatinsk Nuclear Testing Site, Kazakhstan.

A high incidence of skin cancers has been noted around the Semipalatinsk Nuclear Testing Site (SNTS) in Kazakhstan. Recently, basal cell carcinoma (BCC) susceptibility genes, human homolog of the Drosophila pathed gene (PTCH), and the xeroderma pigmentosa group A-complementing gene (XPA), have been cloned and localized on chromosome 9q22.3. To clarify the effect of low-dose irradiation on the occurrence of BCC, we used microdissection and polymerase chain reaction to identify loss of heterozygosity (LOH) at 9q22.3 using BCC samples obtained from this region. Ten Japanese samples were analyzed as controls. LOH with at least 1 marker was identified in 5 of 14 cases from around SNTS, whereas only 1 case with 1 marker was identified among the 10 Nagasaki cases. The total number of LOH alleles from SNTS (8 of 45) was significantly higher than the number from Nagasaki (1 of 26) (P = 0.03). The higher incidence of LOH on 9q22.3 in BCC from around SNTS suggests involvement of chronic low-dose irradiation by fallout from the test site as a factor in the cancers.

Adult↗

PubMed2004

Distribution of Np and Pu in Swedish lichen samples (Cladonia stellaris) contaminated by atmospheric fallout.

The activity concentrations of (237)Np and the two Pu isotopes, (239)Pu and (240)Pu, were determined in lichen samples (Cladonia stellaris) contaminated by fallout from atmospheric nuclear test explosions and the Chernobyl accident. The samples were collected at 18 locations in Sweden, from north to south, between 1986 and 1988 and analysed with high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and alpha spectrometry. Data on the activity ratios (238)Pu/(239+240)Pu and (134)Cs/(137)Cs measured previously were also included in this study for comparison. The (237)Np activity concentration ranged from 0.08 +/- 0.01 to 2.08 +/- 0.17 MBq kg(-1), depending on the location of the sampling site and time of collection. The (239+240)Pu activity concentration ranged from 0.09 +/- 0.01 to 4.09 +/- 0.15 Bq kg(-1), with the (240)Pu/(239)Pu atomic ratio ranging between 0.16 +/- 0.01 and 0.44 +/- 0.03, the higher ratios indicating a combination of weapons test fallout and Chernobyl fallout. The (237)Np/(239)Pu atomic ratios ranged between 0.06 +/- 0.01 and 0.42 +/- 0.04, the lower ratios indicating combination of weapons test fallout and Chernobyl fallout. At a well-defined sampling site at Lake Rogen (62.32 degrees N, 12.38 degrees E), additional lichen samples were collected between 1987 and 1998 to study the distribution of Np and Pu in different layers. The concentrations of the two elements follow each other quite well in the profile.

Air Pollutants, Radioactive↗

PubMed2004

Radioecological software package: an interactive computational system to simulate the behaviour of radionuclides in semi-natural environments.

RSP (Radioecological Software Package) is an interactive support system that simulates the behaviour of radionuclides in semi-natural environments and the consequences on the population in terms of the external exposure. RSP consists of three modules: the first one, soil mobility, simulates the vertical transport of radionuclide in soil using the mathematical model RABES. The second module, soil -to-plant transfer, simulates the radionuclide soil-to-plant transfer factor reported in the literature. Soil properties, vegetation types and environmental conditions are taken into consideration in the simulation process. In the third module, dose assessment, the dose-rate factor in air at a height of 1 m above ground can be calculated for sources distributed in a slab of finite thickness dn sources which are exponentially distributed with depth. The calculations are performed using DAGES Model, a Monte Carlo algorithm developed to simulated the photon transport for the soil/air configuration. A free copy of RSP can be downloaded from the website: http://imasl-apat.unsl.edu.ar.

Air Pollutants, Radioactive↗

PubMed2004

Conclusions on plutonium separation from atmospheric krypton-85 measured at various distances from the Karlsruhe reprocessing plant.

For wide-area atmospheric monitoring, krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 80-90% at a distance of less than 1 km, 70% at 5 km, 40% at 39 km, and 15% at 130 km. At distances up to 40 km, the false alarm rate is less than 3.5%. On average, the fuel released 28 TBq krypton-85 per kg plutonium. For weapons-grade plutonium, the krypton signal would be lower by a factor of 2. Hence, the given percentages correspond to the detection probabilities for the separation of a significant quantity (8 kg) of plutonium per weekly sample under the specific meteorological conditions of the WAK. The minimum separation rates that could have been detected are 2 gram of weapons-grade plutonium per week at a distance of less than 1 km, 40 g/week at 5 km, 200 g/week at 39 km, and 1000 g/week at 130 km.

Air Pollutants, Radioactive↗

PubMed2004

Behaviors of 323Th, 238U, 228Ra and 226Ra on combustion of crude oil terminal sludge.

Crude oil terminal sludge contains technologically enhanced naturally occurring radionuclides such as (232)Th, (238)U, (228)Ra and (226)Ra, thus cannot be disposed of freely without proper control. The current method of disposal, such as land farming and storing in plastic drums is not recommended because it will have a long-term impact on the environment. Due to its organic nature, there is a move to treat this sludge by thermal methods such as incineration. This study has been carried out to determine the behaviors of (232)Th, (238)U, (228)Ra and (226)Ra present in the sludge during combustion at a certain temperature and time. The percentage of volatilization was found to vary between 2% and 70%, (238)U was the most volatile in comparison with (232)Th, (228)Ra and (226)Ra. (238)U is found to be significantly volatilized above 500 degrees C, and might reach maximum volatilization at above 700 degrees C. A mathematical model was developed to predict the percentage of volatilization of (232)Th, (238)U, (228)Ra and (226)Ra contained in the sludge. With this known percentage of volatilization, the concentration of (232)Th, (238)U, (228)Ra and (226)Ra present in the bottom and filter ashes can be calculated.

Air Pollutants, Radioactive↗

PubMed2004

Evaluation of 14C abundance in soil respiration using acclerator mass spectrometry.

To clarify the behavior of 14C in terrestrial ecosystems, 14C abundance in soil respiration was evaluated in an urban forest with a new method involving a closed chamber technique and 14C measurement by accelerator mass spectrometry (AMS). Soil respiration had a higher Delta14C than the contemporary atmosphere. This indicates that a significant portion of soil respiration is derived from the decomposition of soil organic matter enriched in 14C by atmospheric nuclear weapons tests, with a notable time lag between atmospheric 14C addition and re-emission from soil. On the other hand, delta14C in soil respiration demonstrated that 14C abundance ratio itself in soil-respired CO2 is not always high compared with that in atmospheric CO2 because of the isotope fractionation during plant photosynthesis and microbial decomposition of soil organic matter. The Delta14C in soil respiration was slightly lower in August than in March, suggesting a relatively high contribution of plant root respiration and decomposition of newly accumulated and/or 14C-depleted soil organic matter to the total soil respiration in August.

Air Pollutants, Radioactive↗