Cosmic radiation measurements on-board aircraft with the variance method.

The microdosimetric variance-covariance method has been used for cosmic radiation measurements on-board aircraft. Two independent methods of data analysis are presented; the first based on a high energy neutron calibration and the second on identification of single high LET events in the measured multiple event spectrum. Reduced dose levels at high geomagnetic latitudes are observed on one flight in a period of enhanced solar activity as indicated by a reduced ground-level neutron fluence rate.

The use of TEPC for reference dosimetry.

The radiation fields on board aircraft are quite complex and cover an energy range that is unusual in ordinary radiation protection work. Usually dosemeters measure only one radiation quality and the mixture found on board makes measurements complicated. There is also some doubt when it comes to the best choice of quantity for this application and no radiation standards exist for this kind of radiation field.

The response of the sievert instrument in neutron beams up to 180 MeV.

Measurements with a tissue-equivalent proportional counter (TEPC) using the variance-covariance method have been performed in neutron beams between 71 keV and 180 MeV and in the cosmic radiation reference field (CERF) at CERN. The results show that with appropriate linear QD(yD) relations, the ambient dose equivalent can be determined within about 55% in these beams. Build-up measurements show that wall thickness is not crucial for H* determinations at 60 and 180 MeV.

A comparison of three models of 137Cs transfer in forest ecosystems.

The predictions of three models of 137Cs transfer in forest ecosystems (FOA, LOGNAT and FORESTLAND) were compared. The scenario for the model-model comparison consisted of an acute dry deposition of 137Cs over a coniferous forest. The model predictions were subsequently compared (model-data comparison) with values derived from experimental data measured in forests of the Bryansk region in Russia that were contaminated by the Chernobyl accident and that have similar characteristics to the forests described in the scenario.

Experience from retrospective radon exposure estimations for individuals in a radon epidemiological study using solid-state nuclear track detectors.

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 to assess past history of radon exposure.

137Cs availability for soil to understory transfer in different types of forest ecosystems.

A quantitative analysis of 137Cs bioavailability in forest soils in the long term after the Chernobyl NPP accident based on a 3-year (1996-1998) investigation is presented. Five forest sites with different trees, composition and properties of soil were studied to identify factors determining radiocaesium transfer to different understory species. The following parameters were investigated: 137Cs activity concentrations and its speciation in various horizons of forest soil, accumulation of this radionuclide by different species of understory vegetation and distribution of root biomass in the soil profile.

The evasive plausibility.

A frequent practical problem is to assess the probability of a potential single event (X). The event probability P(X) is usually conditional to some assumption (A) and is then written P(X / A). Whether the assumption is valid or not is an unknown fact, but its validity may be assigned a weight psi(A) indicating the observer's belief in its validity.

An evaluation of the ethical principles of the ICRP's radiation protection standards for workers.

After reviewing international recommendations and national standards for occupational radiation exposures, the article summarizes the major ethical theories so as to analyze which theories various ICRP principles presuppose. It also shows how proponents of each ethical theory would support or criticize various radiation principles and practices. Finally the article discusses four ethical issues crucial to the debate over workplace standards for radiation: (1) how to respond to the uncertainty over effects of low-dose exposures; (2) the conditions under which worker consent legitimates higher exposures; (3) whether there ought to be a double standard for worker, vs.

Epstein-Barr virus-transformed lymphoblastoid cell lines of ataxia telangiectasia patients are defective in X-ray-induced apoptosis.

Purpose: To investigate and compare the propensity of Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL) obtained from unaffected healthy individuals and ataxia telangectasia (A-T) patients to undergo apoptosis after X-ray exposure.

Material And Methods: The LCL were exposed to 1-4 Gy X-rays at a dose-rate of 1.36 Gy/min.

Assessment of long-term bronchiolar clearance of particles from measurements of lung retention and theoretical estimates of regional deposition.

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.

Population UV-dose and skin area--do sunbeds rival the sun?

From the perspective of skin cancer risks, sunbed tanning may give the population group of Swedish adolescents a yearly total dose in terms of ultraviolet radiant energy to the skin which is comparable to sunlight. For populations, a dosage scheme is applied, where exposed skin area is estimated to be two to ten times larger in tanning units than in outdoor sunlight. The normal dose fluence rate is multiplied by the exposure time and by the exposed body surface area.

DNA double-strand break repair, DNA-PK, and DNA ligases in two human squamous carcinoma cell lines with different radiosensitivity.

Purpose: Variation in sensitivity to radiotherapy among tumors has been related to the capacity of cells to repair radiation-induced DNA double-strand breaks (DSBs). DNA-dependent protein kinase (DNA-PK) and DNA ligases may affect DNA dsb rejoining. This study was performed to compare rate of rejoining of radiation-induced DSBs, DNA-PK, and DNA ligase activities in two human squamous carcinoma cell lines with different sensitivity to ionizing radiation.

Some aspects on radiation induced transmissible genomic instability.

The early observations on the possible induction of transmissible genomic instability after exposure to ionising radiation has received a strong support in the literature during the last 10 years. Aided by new research tools in biology, the better understanding of the mechanisms behind genomic instability leads to conclusions which are challenging the existing views on the interaction and response of the genome to radiation or chemicals. It has become commonly accepted that the full revelation of biological pathways leading to the loss of stability of the genome will also be a major step in the understanding of carcinogenesis.

RBE for the induction of apoptosis in human peripheral lymphocytes exposed in vitro to high-LET radiation generated by accelerated nitrogen ions.

Purpose: To investigate the relative biological effectiveness (RBE) of accelerated nitrogen ions (32-45 MeV/u) compared with 137Cs gamma-rays for the induction of apoptosis in G0 lymphocytes.

Materials And Methods: Human peripheral G0 lymphocytes were exposed in vitro to doses up to 3 Gy. RBE for the induction of apoptosis was studied at different times after irradiation (0, 24, 48 and 72 h) with the use of three different methods: (1) morphological characterization of apoptotic cells after fluorescence staining; (2) cell size distribution analysis of the cell population to detect apoptotic bodies; and (3) electrophoretic analysis of DNA to detect 'DNA-ladders'.

Biosphere model for high level waste repository.

Method for environmental impact modeling involving uncertainty, overcoming the disadvantage of providing only one upper bound based on accumulated effects from all extreme events. This method provides a suite of upper and lower bounds based on any subset of such extreme events, to be chosen among by the decision maker.

Clearance of particles from small ciliated airways.

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.

Radiation induced apoptosis.

The response to ionising radiation, in terms of level of cell killing, depends on a number of factors that may be grouped into those that are genetically controlled, radiation quality and dosage, and environmental factors. There is a range of genetically controlled cellular properties such as stage of differentiation, mutations in specific genes (such as p53 and bcl-2) and stage of transformation that will determine the ability of the target cell to enter apoptosis. The so-called normal cells, are usually more radiosensitive and the majority of the cell population will enter into an apoptotic death.

Methodology for assessment of exposure to environmental factors in application to epidemiological studies: assessment of exposure to natural ionizing radiation.

This paper reviews the recent progress of passive measurement methods of gamma radiation and radon. Relatively cheap and reliable dosimeters are now available. Results from national and world-wide surveys of natural radiation in bedrock and soils and indoor radon concentrations exist.

Truth or consequence--Bo Lindell's contribution to radiation protection.

Bo Lindell, former chairman and emeritus member of ICRP, former chairman of UNSCEAR, former Director General and emeritus worker of the Swedish RAdiation Protection Institute, is a phenomenon. His profound influence on radiation protection, and indeed on environmental protection and risk research in general, includes a profuse flow of scientific publications on all aspects of protection of man against harmful effects of radiation. In this context, perhaps his most important efforts hitherto are those relating to nuclear power.

What is a reasonable cost for protection against radiation and other risks?

In Sweden, the National Audit Bureau is encouraging attempts at discussing the costs of protection. For many years, a government authority considering new regulations must provide the government with background material illustrating the costs, the expected benefits, and other aspects of the decision. Direct costs should be stated together with nonquantifiable factors indicated by a valuation of whether their consequences are positive or negative.

On communication and comparison of radiation risks.

Comparison with other risks helps to put a radiation risk into perspective and facilitates communication of radiation risk to the public. Twelve recommendations for risk comparisons are given, and some guidelines for risk communication are discussed.

In search of optimum chest radiography techniques.

A nation-wide study of chest radiography in Sweden had previously revealed a large variation in the physical and technical factors involved, in particular the radiation dose. In this study the image quality could not be assessed unambiguously. The aim of the present study was to try to establish a correlation between visual grading of radiographs and physical and technical factors in order to find the optimum chest X-ray system.

The scientific base for the disposal of spent nuclear fuel.

The main objectives of the Swedish expert seminar on spent nuclear fuel disposal were to identify those safety questions for which there is, or will be, a definitive answer, and to establish the degree of uncertainty surrounding those questions which still cannot be satisfactorily answered. The opinion was that the geological environment of the repository can be defined and its behavior predicted with much confidence, assuming the existing environment remains stable. Thus in the short term (a few hundred to thousands of years), the situation is favorable for safe disposal of spent fuel.

Introduction: present knowledge on the effects of radioactive contamination on pregnancy outcome.

This introduction gives a brief review of the effects on pregnancy outcome that might follow radioactive contamination of the environment. These include miscarriages, congenital anomalies, damage to the central nervous system expressed through reduced intelligence and a risk of tumours late in life. Knowledge is fragmentary and field studies are difficult, which lends weight to the attempts at studying the effects of the Chernobyl accident in Europe which are the subject of the present symposium.