Biomedical subjects

K G Andersson

Publications and source records attributed to K G Andersson.

15 recordsLinked to original sources

PubMed2007

137Cs and 90Sr in live and dead reindeer lichens (genera Cladonia) from the "Kraton-3" underground nuclear explosion site.

The contents of 137Cs and 90Sr have been determined in 29 samples of live and dead reindeer lichens (genera Cladonia) collected at the "Kraton-3" underground nuclear explosion site (65.9 degrees N 112.3 degrees E, event year--1978) in Yakutia, Russia in 2002. The area contamination was within the range of 0.36-700 and 0.13-770 kBq m(-2) for 137Cs and 90Sr, respectively. The dead organisms were on average much more contaminated than the live ones. Vertical fractionation of the live lichen carpet demonstrated maximal activity concentrations of both radionuclides in the lower older section of the plants, while for the dead lichens the maximal activity concentrations of 137Cs were detected in the upper part. The vertical distribution of 90Sr was more or less homogeneous in the cushions of dead lichens. Elevated levels of 137Cs and 90Sr activity concentrations were also detected in the re-establishing young lichens growing over the residua of some dead lichens.

Animals↗

PubMed2005

Measurement of contaminant removal from skin using a portable fluorescence scanning system.

The residence time of particulate contamination on the human body is a factor that has an important impact on the accuracy of exposure assessment in the aftermath of an accidental release of radionuclides to the atmosphere. Measurements of particle clearance from human skin were made using an illumination system to excite fluorescence in labelled silica particles and a CCD camera and image processing system to detect this fluorescence. The illumination system consists of high-intensity light emitting diodes (LEDS) of suitable wavelengths arranged on a portable stand. The physically small size of the LEDs allows them to be positioned close to the fluorescing surface, thus maximising the fluorescent signal that can be obtained. The limit of detection was found to be 50 microg of tracer particle per cm2. Experiments were carried out to determine the clearance rates of 10 microm and 3 microm particles from the skin. Results show that, in the absence of any mechanical rubbing of the skin, the clearance of particles from the skin followed an approximately exponential decay with a half-time of 1.5-7.8 h. Skin hairiness and degree of human movement were found, in addition to particle size, to have an important influence on particle fall-off rate.

Aerosols↗

PubMed2005

Requirements of future models for inhabited areas.

Models for inhabited areas are used in a variety of applications for accidental or continuous releases of radioactivity to atmosphere. Pathways of interest are external exposure from radioactive material in the cloud or deposited on indoor and outdoor surfaces and people, inhalation from the plume and from material resuspended from the ground. In developing a model for inhabited areas it is necessary to consider what the end users may need and ensure that the model is appropriate for the application; different levels of detail may be appropriate for different applications. This paper considers the main processes governing exposure in inhabited areas, commenting on the extent to which we understand them and how well current models reflect this understanding. It also identifies where the authors believe future modelling is needed and the key areas where the current inhabited area models could be improved.

Air Pollution, Indoor↗

PubMed2005

Deposition of contaminant aerosol on human skin.

Over recent years, it has been established that deposition of various types of pollutant aerosols (e.g., radioactive) on human skin can have serious deleterious effects on health. However, only few investigations in the past have been devoted to measurement of deposition velocities on skin of particles of the potentially problematic sizes. An experimental programme has shown the deposition velocities on skin of particles in the ca. 0.5-5 microm AMAD range to be high and generally associated with great variations. A series of investigations have been made to identify some of the factors that lead to this variation. Part of the variation was found to be caused by differences between individuals, whereas another part was found to be related to environmental factors. The identification of major influences on skin contaminant deposition is important in estimating health effects as well as in identifying means for their reduction.

Aerosols↗

PubMed2005

Long-term stability of decontamination effect in recreational areas near the town Novozybkov, Bryansk Region, Russia.

In 1995 and 1997, experimental decontamination campaigns were carried out in two recreational areas, Novie Bobovichi and Guta-Muravinka, near the town of Novozybkov, Bryansk Region, Russia. These areas were strongly affected by the Chernobyl fallout in 1986. In order to examine the long-term stability of the clean-up procedures, a programme has been carried out to continuously monitor the radiological situation in and around the decontaminated areas. This follow-up program consists of regular (1-3 times per year) measurements of absorbed gamma-dose rate in air (DR) at reference indoor and outdoor locations, repeated DR measurements on a grid, and gamma-spectrometric analysis of soil and other environmental samples. Very similar dynamics of the Chernobyl-related DR, mostly attributed to radiocaesium decay, were found in all the locations. For the period under study (September 1995-May 2003), the half-lives (years) for the reduction in radiocaesium-dependent DR contribution due to contaminant migration (in the following termed 'DRM half-lives') were, respectively, 52+/-26, 57+/-23, 43+/-21, 46+/-15, and 80+/-56 for the following locations: untreated outdoors, treated outdoors, untreated indoors, treated indoors, and undisturbed forest-grassland plots outside the recreational areas. These relatively high values of the current DRM half-lives correspond very well with the results of soil core analyses, which showed no time-dependent changes in the mean mass depths of the (137)Cs distribution, neither at treated nor at undisturbed plots. The following signs of natural restoration of the disturbed forest-meadow ecosystems have been observed at treated areas: formation of a new litter layer, development of grassy spots, mushroom growths and new generations of pines and birches. The levels of the (137)Cs content in grass and mushrooms from treated plots were one or two orders of magnitude lower, than those registered in the samples from untreated areas. The follow-up study demonstrates the long-term stability and efficiency of the decontamination carried out. There are two main reasons for the sustainment of the effects: careful implementation of adequate clean-up procedures and natural strong fixation of radiocaesium in soil-associated matrices of the ecosystems.

Agaricales↗

PubMed2005

Reduction of external dose in a wet-contaminated housing area in the Bryansk Region, Russia.

An investigation of the feasibility of reducing the external dose rate in a recreational housing area located between the settlements of Guta and Muravinka, Bryansk Region, Russia, which had been contaminated by the Chernobyl accident more than a decade earlier was made. Removal of contaminated topsoil was carried out over an area of about 2000 m2, optimising the thickness of the removed layer according to an assessment of the vertical contaminant distribution. A layer of clean sand was applied to shield against radiation from residual contamination in the ground. Careful monitoring of dose rates in reference positions showed that this could reduce the dose rate outdoors by about a factor of 6. The replacement of a roof was found to reduce the dose rate considerably inside the house. A cost analysis of the operation is presented.

Air Pollutants, Radioactive↗

PubMed2005

Estimation of doses received in a dry-contaminated residential area in the Bryansk region, Russia, since the Chernobyl accident.

In nuclear preparedness, an essential requirement is the ability to adequately predict the likely consequences of a major accident situation. In this context it is very important to evaluate which contributions to dose are important, and which are not likely to have significance. As an example of this type of evaluation, a case study has been conducted to estimate the doses received over the first 17 years after the Chernobyl accident in a dry-contaminated residential area in the Bryansk region in Russia. Methodologies for estimation of doses received through nine different pathways, including contamination of streets, roofs, exterior walls, and landscape, are established, and best estimates are given for each of the dose contributions. Generally, contaminated soil areas were estimated to have given the highest dose contribution, but a number of other contributions to dose, e.g., from contaminated roofs and inhalation of contaminants during the passage of the contaminated plume, were of the same order of magnitude.

Air Pollutants, Radioactive↗

PubMed2005

The STRATEGY project: decision tools to aid sustainable restoration and long-term management of contaminated agricultural ecosystems.

The STRATEGY project (Sustainable Restoration and Long-Term Management of Contaminated Rural, Urban and Industrial Ecosystems) aimed to provide a holistic decision framework for the selection of optimal restoration strategies for the long-term sustainable management of contaminated areas in Western Europe. A critical evaluation was carried out of countermeasures and waste disposal options, from which compendia of state-of-the-art restoration methods were compiled. A decision support system capable of optimising spatially varying restoration strategies, that considered the level of averted dose, costs (including those of waste disposal) and environmental side effects was developed. Appropriate methods of estimating indirect costs associated with side effects and of communicating with stakeholders were identified. The importance of stakeholder consultation at a local level and of ensuring that any response is site and scenario specific were emphasised. A value matrix approach was suggested as a method of addressing social and ethical issues within the decision-making process, and was designed to be compatible with both the countermeasure compendia and the decision support system. The applicability and usefulness of STRATEGY outputs for food production systems in the medium to long term is assessed.

Agriculture↗

PubMed2004

A critical evaluation of the strategy project.

The STRATEGY project (sustainable restoration and long-term management of contaminated rural, urban and industrial ecosystems; www.strategy-ec.org.uk) addressed the need for a holistic decision framework for the selection of optimal remediation strategies for long-term sustainable management of contaminated areas in Western Europe. The project considered both technical and social aspects of implementing restoration strategies for urban and rural environments. The importance of considering socially relevant objectives in addition to the dose reduction was emphasised. A critical evaluation was carried out on 101 selected countermeasures, (including rural waste disposal options), a model was developed to aid optimising countermeasure strategies and a method of carrying out participatory decision-making suggested. The outputs of the project are described and critically evaluated.

Decision Support Systems, Management↗

PubMed2003

Iodine-129 and caesium-137 in Chernobyl contaminated soil and their chemical fractionation.

Soil samples from areas in Belarus, Russia and Sweden contaminated by the Chernobyl accident were analysed for (129)I by radiochemical neutron activation analysis, as well as for 137Cs by gamma-spectrometry. The atomic ratio of (129)I/137Cs in the upper layer of the examined soil cores ranged from 0.10 to 0.30, with an average of 0.18, and no correlation between (129)I/137Cs ratio and the distance from Chernobyl reactor to sampling location was observed. It seems feasible to use the (129)I/137Cs ratio to reconstruct the deposition pattern of 131I in these areas. The association of (129)I and 137Cs in the Chernobyl soil and Irish Sea sediment was investigated by a sequential extraction method. Similar speciation of (129)I in the Chernobyl soil and Irish Sea sediment was found. Approximately 70% of (129)I is bound to oxides and organic matter, and 10-20% is in the readily available phase, while most of the 137Cs (73%) in Chernobyl soil remains in the extraction residue.

Cesium Radioisotopes↗

PubMed2002

Weathering of radiocaesium contamination on urban streets, walls and roofs.

Recent investigations in Russia have emphasised the significance of dose contributions from contamination on urban streets and roof pavings, and, typically to a lesser extent, walls in the urban environment. The crucial factor determining the magnitude of these contributions is the retention of the contamination by the different types of urban surface. Since the Chernobyl accident, a series of long-term field studies has been carried out on urban streets, walls and roofs, to examine the weathering processes of 137Cs on the various surface types. The derived time-functions are applied to estimate resultant long-term doses to inhabitants of an urban centre. The paper highlights the effect on caesium retention of surface material characteristics.

Cesium↗

PubMed2002

Radiation dose implications of airborne contaminant deposition to humans.

In nuclear accident consequence assessment, dose contributions from radionuclide deposition on the human body have in the past generally been either ignored or estimated on the basis of rather simple models. Recent experimental work has improved the state of knowledge of relevant processes and parameter ranges. The results presented in this paper represent a first approach to a detailed assessment of doses from radiopollutant deposition on the human body, based on contaminant-specific data. Both the dose to skin from beta-emitters and the whole-body dose from gamma-emitters on body surfaces were found to give potentially significant contributions to dose. Further, skin penetration of some contaminants could lead to significant internal doses.

Air Pollutants, Radioactive↗

PubMed2001

Dynamic behaviour of 137Cs contamination in trees of the Briansk region, Russia.

Seven trees were felled in the Briansk region in 1997. The trees were sectioned for sampling, both at different heights and according to year rings, and samples were analysed for content of 137Cs. In general, the specific activity of 137Cs was much higher in the fresh parts of the three (needles, leaves and twigs) than in the core wood. The year ring study showed that 137Cs had penetrated deeply in to the trunk, and no peak was detectable in the year ring corresponding to the Chernobyl accident in 1986. The specific activity in the trunk wood had a maximum at the height corresponding to the growth years at approximately 1986. Neutron activation analysis was used to analyse for stable Cs. The results showed that the relationship between concentrations of 137Cs and stable caesium is much higher in the newer parts of growing trees than in the older parts. Together with a tendency of inward migration this leads to a preliminary conclusion that the 137Cs activity will continue to accumulate in the core wood.

Cesium Radioisotopes↗

PubMed1999

Decontamination in a Russian settlement.

Decontamination was carried out in an area with three houses in Novo Bobovichi, Bryansk region, Russia, in the autumn of 1995. It was demonstrated that significant reductions in the dose rate both indoor (DRF = 0.34) and outdoor (DRF = 0.20) can be achieved when a controlled cleaning is undertaken. This paper describes the decontamination work carried out and the results obtained. The roofs of the houses were swept and cleaned by special roof cleaning equipment. The soil around the houses was removed by hand while carefully monitoring the ground for residual contamination. By monitoring the decline in the dose rate during the different stages of the work the dose reducing effect of each action has been measured.

Cesium Radioisotopes↗

PubMed1997

Health impacts of large releases of radionuclides. The fate and impact of radiocontaminants in urban areas.

The Chernobyl accident made it clear that the contaminants released after a severe nuclear accident may spread over large areas, and thereby form a significant external radiation hazard in areas of high population density. Since then, the weathering effects on the deposited radiocontaminants (essentially radiocaesium) have been followed on different types of surface in urban, suburban and industrial areas in order to enable an estimation of the long-term impact of such events. Analytical expressions have been derived for the typical behaviour of radiocaesium on the different surfaces, and dose measurements and calculations for different urban environments have pinpointed which surfaces generally contribute most to the dose and consequently are most important to clean. At this point, after nearly a decade, the dose rate from horizontal pavements has decreased by at least a factor of 10, whereas the dose rate from an area of soil or a roof has generally only been halved. The contamination on walls is the most persistent: it has only decreased by 10-20%.

Cesium Radioisotopes↗