Rolf Falk

Rolf Falk
Strålsäkerhetsmyndigheten

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98
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Publications

Publications (98)
Method
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Working environment in hot lab at hospitals.
Article
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Particulate air pollution, for example, from ultrafine (UF) particles, has negative health effects. However, there is still limited knowledge regarding the fate of inhaled particles in the human body. To describe the normal lung deposition and 1 week particle retention of indium-111 labeled UF carbon particles in healthy subjects. Additionally, the...
Article
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Long-term clearance (21 days) from small airways was studied in 9 patients with chronic bronchitis (CB), 65 +/- 10 (mean +/- SD) years, and was compared to 15 age-matched healthy subjects of 67 +/- 7 (mean +/- SD) years. Six of the CB patients were studied twice. All subjects inhaled monodisperse 6 microm Teflon particles labelled with 111In with a...
Article
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A new method to determine the air concentration of 220Rn, commonly referred to as thoron, has been developed. The method is insensitive to the presence of any concentration of 222Rn. Air turbulence, humidity and temperature do not influence the measurement. This method was primarily developed for field measurement of 220Rn and 212Pb concentrations...
Article
In radiation protection dosimetry the quantity of interest is the effective dose (E); the dose limit to an adult worker applies to the sum of the relevant doses from external exposures and the relevant committed effective doses from intakes of radionuclides, during the same period of time. A EURADOS study was carried out to investigate how the resu...
Article
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Human pulmonary retention of 35 nm 99mTc-labeled carbonaceous particles, produced with a modified Technegas generator, was followed for 24 h using a gamma camera imaging technique. Nine healthy subjects and four asthmatics inhaled the test particles. Particle labeling stability was tested in vitro during 48 h. We also measured in vivo leaching in b...
Article
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Ambient particles are believed to be a specific health hazard, although the underlying mechanisms are not fully understood. There are data in the literature indicating fast and substantial systemic uptake of particles from the lung. The present authors have developed an improved method to produce ultrafine particles with more stable radiolabelling...
Article
Data from measurements on the body burden of 134Cs, 137Cs and 40K in various Swedish populations between 1959 and 2001 has been compiled into a national database. The compilation is a co-operation between the Departments of Radiation Physics in Malmö and Göteborg, the National Radiation Protection Authority (SSI) and the Swedish Defense Research Ag...
Article
The fallout in Sweden of radiocesium from nuclear weapons tests during the 1960's (137Cs) and from the Chernobyl accident in 1986 (134Cs and 137Cs) has transferred to humans through different ecological pathways. Data from whole-body burden measurements of 134Cs, 137Cs, and 40K in various Swedish populations between 1964 and 2002 have been compiled...
Article
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The objective of this study was to investigate if long-term clearance from small airways is dependent on normal ciliary function. Six young adults with primary ciliary dyskinesia (PCD) inhaled 111 Indium labelled Teflon particles of 4.2 μm geometric and 6.2 μm aerodynamic diameter with an extremely slow inhalation flow, 0.05 L/s. The inhalation met...
Article
Once the EC Directive 96/29 has been implemented into national regulation across Europe, the coordination of dosimetry laboratories for the monitoring of occupational exposures becomes the principal aim to achieve. Within this framework the European Radiation Dosimetry Group, EURADOS, carried out an Action on ‘Harmonisation of Individual Monitoring...
Article
Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accr...
Article
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Studies seeking direct estimates of the lung cancer risk associated with residential radon exposure lasting several decades have been conducted in many European countries. Individually these studies have not been large enough to assess moderate risks reliably. Therefore data from all 13 European studies of residential radon and lung cancer satisfyi...
Article
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In February 2001 the Swedish Radiation Protection Authority, SSI, presented an updated risk assessment for radon in indoor air and in drinking water. SSI now estimates that about 500 cases of lung cancer, 18 percent of the total incidence, are related to exposure to indoor radon in dwellings in Sweden. SSI deems it unlikely that the annual number o...
Article
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The prevalence of respiratory symptoms increases with age. Age has been found to be negatively associated with large airway clearance. The small airways region is considered important for development of airway disease. Clearance after the first 24 h was studied in 46 healthy subjects with a wide age distribution, (mean 42, range 19-81 yrs). All sub...
Article
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Impaired mucociliary clearance is a hallmark of cystic fibrosis (CF). Early morphological changes first appear in the small airways. Lung clearance was investigated in 11 young CF adults with mild-to-moderate lung disease using a method depositing particles mainly in the small airways. Radiolabelled Teflon particles (6 microm) were inhaled with an...
Article
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To determine the risk of lung cancer associated with exposure at home to the radioactive disintegration products of naturally occurring radon gas. Collaborative analysis of individual data from 13 case-control studies of residential radon and lung cancer. Nine European countries. 7148 cases of lung cancer and 14,208 controls. Relative risks of lung...
Article
The catalogue of dosemeters and dosimetric services within the European Union (EU) Member States and Switzerland that was issued by EURADOS in the year 2000 has been updated and extended with information on dosimetric services in the new EU Member States and Bulgaria, Croatia, Romania, Serbia and Montenegro, and Ukraine. The total number of dosimet...
Article
The European Radiation Dosimetry Group, EURADOS, established a working group consisting of experts whose aim is to assist in the process of harmonisation of individual monitoring as part of the protection of occupationally exposed workers. A catalogue of facilities and internal dosimetric techniques related to individual monitoring in Europe has be...
Article
Part of the action of the EURADOS working group (European Radiation Dosimetry Group) on "Harmonisation of Individual Monitoring in Europe" was to investigate how the results from personal dosemeters for external radiation, from monitoring for internal exposure and from workplace monitoring, can be combined into a complete and consistent system of i...
Article
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Three adult volunteers (2 males and 1 female) have ingested radioactive caesium in two edible forms in order to compare the gastrointestinal uptake and the subsequent short-term and long-term biokinetics. Foodstuffs made of fresh-water fish or mushrooms from regions in Sweden of high 137Cs deposition was ingested together with a 134CsCl-solution mi...
Article
The EURADOS Working Group II on 'Harmonisation of individual monitoring' consists of experts from almost all EU Member States and Newly Associated States (NAS), involved in tasks related to the assessment of doses for internal and external radiation. The final objective is to achieve harmonisation in individual monitoring for occupational exposures...
Article
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Lung cancer risk estimation in relation to residential radon exposure remains uncertain, partly as a result of imprecision in air-based retrospective radon-exposure assessment in epidemiological studies. A recently developed methodology provides estimates for past radon concentrations and involves measurement of the surface activity of a glass obje...
Article
Ten healthy nonsmokers inhaled 6-microm (aerodynamic diameter) Teflon particles labelled with 111In twice, once with the shallow bolus technique (volumetic lung depth 76+/-20 mL ([+/- SD]) and once with the extremely slow inhalation technique (0.05 L/s). The radioactivity in the lungs was measured at 1 and 24 hours as well as at 1, 2, and 3 weeks a...
Article
Lifetime risk projections depend greatly on both background lung cancer rates and the selection of the risk model. Since background lung cancer rates differ from subject populations and the time, etiological risk of lifetime lung cancer mortality per unit radon exposure in WLM should be estimated for each subject population and the time of interest...
Article
Implanted long-lived radon decay products in glass surfaces have been used as a measure of past radon exposure in homes. Special track-etch devices (so-called 'retro-detectors') attached to the glass surface, have the ability to specifically measure the implanted activity of 210Po in situ. Calibrating these devices for 210Po is fairly straightforwa...
Article
The first Norwegian study of historic radon concentrations in 17 dwellings in the high radon areas in Norway has been conducted as part of an international field intercomparison during 1998. The retrospective radon concentration is estimated via measurements of Po-210, the long-lived decay product of Rn-222 implanted in glass surfaces of objects li...
Article
The results of field investigations of natural radiation exposures of the general population in two stable rural communities in Yugoslavia are presented. The principal emphasis was on exposures to contemporary indoor radon, but measurements of external penetrating radiation absorbed dose rates in air were carried out in the majority of cases. In ad...
Article
The relation between increased risk of lung cancer and exposure to indoor radon is assessed in epidemiological studies. Both the quality and reliability of smoking data and the radon exposure data are of primary importance. Contemporary measurement of radon concentration in the dwellings of individuals in a case-control study is traditionally used...
Article
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The First International Intercomparison and Intercalibration Meeting for Thoron and its Progeny and Thoron/Radon Mixture was organized to compare techniques for determining concentrations and particle size distributions of and mixtures of and . The meeting was held at Elliot Lake, Canada, November 2–6, 1992. We have reported results of activity siz...
Article
Experiments with a bolus technique suggest that retained fractions in the airways are dependent on the geometric diameter of the particles. This view has been adopted by the International Commission on Radiological Protection (ICRP) in its new human respiratory tract model (HRTM). The aim of the present study was to test this view by the use of an...
Article
Some of the quality assurance tasks of whole-body counting are specific to that method of measurement, whereas others are similar to those of gamma spectrometric sample measurements. Quality assurance in whole-body measurement and the associated calculation of internal doses is a complex matter. The uncertainty in the measurement geometry between t...
Article
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Twelve healthy nonsmokers inhaled monodisperse Teflon particles labelled with 51Cr (half-life 27.8 days) with an aerodynamic diameter (dae) of 6.1 microns, 5 at a normal flow, 0.5 L/s, and 7 at an extremely slow flow, 0.05 L/s. Lung retention after 24 hours was measured for about 6 months and could be well described by a 2-component exponential fun...
Article
In recent years, there has been a debate on whether a considerable fraction of particles is retained after 24 h in the tracheobronchial region. In the present study, 8 healthy subjects inhaled 6.2-microns monodisperse Teflon particles labeled with 111 In twice, at flow rates of 0.45 and 0.045 L/s. According to theoretical calculations, the particle...
Conference Paper
Full-text available
Article
Measurements of 220Rn have been performed in some 90 buildings during 1992 and 1993, as parts of two different investigations. In the first study, 220Rn progeny measurements were undertaken in 53 dwellings and 7 workplaces at 13 different locations in south and central Sweden. Most buildings were situated in areas with elevated natural thorium conc...
Article
A reference chamber has been constructed for the purpose of calibrating instruments continuously measuring 220Rn concentration in air. It consists of a 232Th source in a solution from which the produced 220Rn is extracted by bubbling air through the solution. The gas is dehumidified in a cooling system, where the condensed water is fed back into th...
Article
The radon exposure of the past is important in epidemiological studies where an assessment of lung cancer risk from indoor radon exposure is evaluated. The long-lived decay product, 210Pb (), is implanted into indoor surfaces by alpha recoils and can be monitored to give information about the previous radon history. This gives an alternative or com...
Conference Paper
Full-text available
An investigation was done in 1994 to assess of the intake of Cs-137 from foodstuff by Swedes Food baskets representative of the yearly total food consumption were collected. The population-weighted average of the intake for year 1994 was estimated to be 270 +/-50 Bq. This gives a committed effective dose equivalent of 3.6 micro Sv. The body burden...
Article
Ten healthy males inhaled monodisperse Teflon particles (geometric diameter 3.6 microns, aerodynamic diameter 5.3 microns) labeled with 195Au (half-life 183 days). The leakage of 195Au from the particles in vitro in water was less than 0.2% per year. Retention over the thorax was followed for about 900 days using two separate detector systems. One...
Article
Ten healthy males inhaled monodisperse Teflon particles (geometric diameter 3.6 μm, aerodynamic diameter 5.3 μm) labeled with ¹⁹⁵Au (half-life 183 days). The leakage of ¹⁹⁵ Au from the particles in vitro in water was less than 0.2% per year. Retention over the thorax was followed for about 900 days using two separate detector systems. O...
Article
Large lung retentions (up to 50%) of particles < or = 4 microns inhaled with a bolus technique at a penetration depth less than dead space have been reported to occur after 24 h. This retention may be due to retarded clearance of particles deposited in the airways of the tracheobronchial tract; an alternative explanation could be that particles are...
Article
The effect of phagolysosomal size on dissolution of cobalt oxide particles was evaluated in two different macrophage systems: alveolar macrophages (AM) of human smokers with phagolysosomes enlarged by ingested cigarette smoke products, and rabbit AM incubated in vitro with sucrose, which causes swelling of the phagolysosomes by osmosis. Human AM fr...
Chapter
Whole-body counting is an established method for the determination of radionuclides that emit X or gamma radiation in the human body. Quantitative measurement is necessary for radiation protection purposes, but requires reliable calibration. Whole body counters are generally calibrated by means of phantoms, i.e. containers resembling the human body...
Article
Inhaled decay products of 222Rn are the dominant components of the natural radiation exposure to the general population. Limits have been introduced in Sweden, and recommendations were made in 1980 for decreasing indoor 222Rn concentration. The need for the coordinated calibration of measuring instruments as well as for quality assurance was obviou...
Article
Full-text available
A multiple time analysis technique has successfully been applied for measurements of environmental levels of 220Rn using a flow-through Lucas radon detector. The method is based on selective alpha counting of the short-lived nuclide 216Po. Owing to its short half-life (0.145 s), the alpha particle emitted at the decay of a 220Rn atom will, within a...
Article
Full-text available
In order to assess the risk for high thoron levels indoors, measurements of thoron progeny have been performed in a number of buildings in Sweden. Some of the measurements have been made in detached houses in areas with elevated natural thorium concentrations. The radon progeny concentration was measured at the same time. Up to the summer of 1991 m...
Article
Full-text available
Experimental studies of the uptake and deposition pattern in the human airways of inhaled radon decay products have been carried out using two different techniques. The total deposited fraction of inhaled decay products was assessed by simultaneous determination of the radon decay product concentration in inhaled and exhaled air. The deposition in...
Article
A multiple time analysis technique has successfully been applied for measurements of environmental levels of 220Rn using a flow-through Lucas radon detector. The method is based on selective alpha counting of the short-lived nuclide ²¹⁶Po. Owing to its short half-life (0.145 s), the alpha particle emitted at the decay of a ²²⁰Rn atom will, within a...
Article
Full-text available
Experimental studies of the uptake and deposition pattern in the human airways of inhaled radon decay products have been carried out using two different techniques. The total deposited fraction of inhaled decay products was assessed by simultaneous determination of the radon decay product concentration in inhaled and exhaled air. The deposition in...
Article
In order to assess the risk for high thoron levels indoors, measurements of thoron progeny have been performed in a number of buildings in Sweden. Some of the measurements have been made in detached houses in areas with elevated natural thorium concentrations. The radon progeny concentration was measured at the same time. Up to the summer of 1991 m...
Article
Full-text available
We studied phagolysosomal pH in rabbit alveolar macrophages (AM) incubated with 0-15 microM chloroquine. There was a dose-related increase in pH with chloroquine concentration. Electron microscopy showed that chloroquine increased lysosomal size. In a second experiment we studied dissolution of radiolabeled cobalt oxide particles by rabbit AM, phag...
Article
Full-text available
The radiation dose from the Chernobyl release to the Swedish population via contaminated foodstuffs has been estimated. The estimation is based on results from whole-body measurements of a country wide random selected group of persons and a reference group of employ~es from the Swedish Radiation Protection Institute (SS!). A description of the tech...
Article
After the Chernobyl accident small particles with high activities were detected on the ground. These 'hot particles' contained � and ? emitters and sometimes a emitters. Two microdosimetric techniques have been tested, to determine experimentally the absorbed dose to tissue at distances between 2 �m and 40 �m from a 'hot particle'. With electric cu...
Article
After the Chernobyl accident small particles with high activities were detected on the ground. These 'hot particles' contained ß and ? emitters and sometimes a emitters. Two microdosimetric techniques have been tested, to determine experimentally the absorbed dose to tissue at distances between 2 µm and 40 µm from a 'hot particle'. With electric cu...
Article
Full-text available
A simple procedure to calibrate and characterize a recently developed radon-222 reference instrument is described. The system, which is now used as the official national Swedish reference, is quick and easy to use. Systematic as well as random errors are smaller than in an earlier system and compare well with other systems, as has been shown in a n...
Article
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Twenty-four nonsmoking males, all without history of pulmonary disease, were randomly divided into four groups of six subjects each. The subjects in each group inhaled monodisperse Teflon particles labelled with 111In (half-life 2.83 days); 8.2, 11.5, 13.7 and 16.4 micron aerodynamic diameter, respectively. Radioactivity in head and throat, lung an...
Article
Six healthy nonsmoking males inhaled 4-micron diameter Teflon particles labeled with chromium-51. Lung retention was measured for approximately 300 days. Three subjects inhaled "high-leaching" particles and three "low-leaching" particles. The high-leaching leaching particles leached 0.26%/day in water at 37 degrees C for the first 100 days and the...
Article
Inhaled particles deposited on the tracheobronchial part of the lung are eliminated via the mucociliary transport or coughing within one or two days. Compared to tracheobronchial clearance alveolar clearance is a much slower process. This paper reports on studies that used 4. 13 mu m monodisperse Teflon particles labeled with **5**1Cr which has a h...
Article
Full-text available
Experimental studies of the fraction of inhaled radon daughters deposited in human airways have been carried out with two different techniques. The fraction deposited in the lung region is assessed by external gamma measurement of the subject. The fraction deposited in the whole respiratory system is assessed by simultaneous determination of the ra...
Article
Experimental studies of the fraction of inhaled radon daughters deposited in human airways have been carried out with two different techniques. The fraction deposited in the lung region is assessed by external gamma measurement of the subject. The fraction deposited in the whole respiratory system is assessed by simultaneous determination of the ra...
Article
Full-text available
For an accurate determination of the airborne radon daughter concentration, the counting efficiency of the alpha detector for filter or screen samples is of prime importance. The technique presented is based on simultaneous alpha- and gamma - measurements of bismuth-214 and polonium-214 in air filter or screen samples. A filter or screen sample is...
Data
Full-text available
In this experiment the counting efficiency for asurface barrier detector for alpha-measurements of radon daughters collected on wire screens was determined for different mesh sizes and for varying flow rates. The wire mesh screens evaluated were 635, 310, 180, and 60. The wire screens used are set in brass holders. Screen counting efficiencies were...
Data
The purpose of this series of experiments was to determine the collection efficiency of the unattached radon daughters for 63S, 310, 180, and 60 mesh wire" screens. To evaluate the unattached fraction, 2 test chambers (tubes) were developed to allow for a variation of sampling times and flowrate in non-aerosol condition (<70 particles/cm3) . The va...
Article
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Sammanfattning Målsättningen för studien har varit att ge urrlerlag för anvisningar cm beb:wet CN mätningar in vive vid uranarbete och anviSning CN lämplig metodik för detta. I målsättningen har också ingått uppskattning av stråldoser till personal vid ASEA-A'IOl<B bränslefabrik från inhalerat oH:sligt uran. Efter litteraturstudier av intemationell...
Article
Full-text available
The dose of radiation to the human body and some of its organs after intravenous administration of 75Se-sodium selenite for diagnostic purposes has been calculated on the basis of followup of 26 patients for as long as 517 days with measurements of: 1. The retention of 75Se in the whole body. 2. The retention of 75Se in the blood, liver, kidneys, o...
Article
The dose of radiation to the human body and some of its organs after ; intravenous administration of ⁷⁵Se-sodium selenite for diagnostic purposes ; was calculated on the basis of followup of 26 patients, for as long as 517 days ; with measurements of: the retention of ⁷⁵Se in the whole body; the ; retention of f ⁷⁵Se in the blood, liver...