[en] With 3-month simultaneous measurements of thoron and its progeny concentrations in the lowest floors of 109 homes, the geometric mean (GM) of thoron equilibrium factor was determined to be 0.019 with a geometric standard deviation (GSD) of 3.63. Combined with the analysis from results obtained from a previous study in 138 homes, the GM of thoron equilibrium factor was determined to be 0.022 with a GSD of 3.02. The results indicate that the F value of 0.02 for thoron recommended by UNSCEAR is a reasonable value for those Canadian homes tested. Published by Oxford Univ. Press on behalf of the Canadian Government 2011. (authors)

[en] The paper intends to outline the activities of the UNSCEAR and to summarize the content of its most recent report to the General Assembly. This purpose is made difficult by the very large amount of information it contains: only the most general conclusions will therefore be presented and the reader is referred to the original publication for a detailed description of the conditions under which such conclusions were derived. (orig.)

[en] This study has estimated the concentrations of radon gas and respirable ore dust in the Merelani underground tanzanite mines. Two different portable monitors were used to measure the radon gas and respirable ore dust concentrations respectively. The mean radon gas concentration (disintegrations per second per cubic meter) ranges from 40.1 Bq/m"3 to 4.2x10"3 Bq/m"3 with the geometric mean of 118.4 Bq/m"3 which is below the ICRP workplace guidance level of 500 – 1500 Bq/m"3. The estimated mean annual effective dose (D) was 1.6 mSv which is significantly lower than the external exposure annual effective dose of 20 mSv and the annual organ dose limit of 2.4 mSv. The overall concentrations of respirable ore dust arithmetic mean was 18.2 g/m"3 and the geometric mean of 2.1 g/m"3 which is very high compared to the guidance level of 2 g/m"3. The respirable dust was mainly produced during drilling and blasting of rocks, under normal conditions the geometric mean of respirable gas concentrations was 0.8 g/m"3. It is recommended that immediate intervention such as providing proper ventilation during the two processes to dilute radon levels in underground mines and the monitoring should be done regularly. (author)

[en] After a short historical review, the goals of the ICRU are first presented: definition of quantities and units to be used in the field of ionising radiation, recommendations of measurement procedures for these quantities, definitions of terms and concepts, and investigation and selection of physical parameters. As far as the other international organisations are concerned, some of the main achievements are briefly presented for the IEC, UNSCEAR, ICRDP, WHO and IAEA. Besides technical developments and dosimetric intercomparisons, the importance of the education and of the continuous information of the radiologists is stressed. The role played by the CEC in education is recognised in the field of radiation protection in diagnostic radiology. (author)

[en] The author presents an outline review of his twenty five years' experience as a founder delegate and UK representative of UNSCEAR, from which post he retired in 1982. (U.K.)

[en] The objective of this study was to measure indoor radon concentrations in the expected high risk area around Ipoh in Kinta Valley, Perak. The area was chosen based on its own special characteristics. The measurements were carried out by means of long term exposure (3 months) using CR-39 solid state nuclear track detector. The mean indoor radon concentration in Ipoh was 45 Bq/ m"3 which is equivalent to effective dose of 1.1 mSv/ y. This value was higher compared to low or normal area in Bangi, Selangor but comparable to the world average value reported by UNSCEAR. The maximum value of indoor radon concentration measured was 87 Bq/ m"3. (author)

[en] In this Paper two elements of a multiphase analysis of radiation exposures in the living environment - the human health effects of ionizing radiation and the implications for radiation safety policy and practices - are presented. Part 1 draws together the current state of scientific knowledge and insight about the human health effects of radiation, describing these in terms of known cause-related deterministic effects and of the estimated incidence of stochastic effects as defined by biostatistics and biological models. The 1988 UNSCEAR report provides an authoritative basis for such an examination. Part 2 explores some of the major implications that the state-of-the-art of radiation biology has - or should have - for radiation safety policy and practices. (author)

[en] This paper provides the update of the reference dose distribution proposed by G.A.M. Web and D. Beninson in Annex E to the UNSCEAR 1977 Report. To demonstrate compliance with regulatory obligations regarding doses to individuals, they defined it with the following properties: 1) The distribution of annual doses is log-normal; 2) The mean of the annual dose distribution is 5 m Gy (10% of the ICRP 1977 dose limit); 3) The proportion of workers exceeding 50 m Gy is 0.1%. The concept of the reference dose distribution is still important to understand the inherent variation of individual doses to workers controlled by source-related and individual-related efforts of best dose reduction. In the commercial nuclear power plant, the dose distribution becomes the more apart from the log-normal due to the stronger ALARA efforts and the revised dose limits. The monitored workers show about 1 m Sv of annual mean and far less than 0.1% of workers above 20 m Sv. The updated models of dose distribution consist of log-normal (no feedback on dose X) ln(X)∼N(μ,σ²), hybrid log-normal (feedback on higher X by ρ) hyb(ρX)=ρX+ln(ρX)∼N(μ,σ²), hybrid S_B (feedback on higher dose quotient X/(D-X) not close to D by ρ) hyb[ρX/(D.X)]∼N(μ,σ²) and Johnson's S_B (limit to D) ln[X/(D-X)]∼N(μ,σ²). These models afford interpreting the degree of dose control including dose constraint/limit to the reference distribution. Some of distributions are examined to characterize the variation of doses to members of the public with uncertainty. (author)

[en] Indoor radon levels in 20 dwellings of rural areas at the Kozak-Bergama (Pergamon) granodiorite area in Turkey were measured by the alpha track etch integrated method. These dwellings were monitored for eight successive months. Results show that the radon levels varied widely in the area ranging from 11 ±1 to 727 ±11 Bq m^-3 and the geometric mean was found to be 63 Bq m^-3 with a geometric standard deviation of 2 Bq m^-3. A log-normal distribution of the radon concentration was obtained for the studied area. Estimated annual effective doses due to the indoor radon ranged from 0.27 to 18.34 mSv y^-1 with a mean value of 1.95 mSv y^-1, which is lower than the effective dose values 3-10 mSv given as the range of action levels recommended by International Commission on Radiation Protection. All dosimetric calculations were performed based on the guidance of the UNSCEAR 2000 report. (authors)

[en] At its 58th session in May 2011, the United Nations Committee on the Effects of Atomic Radiation (UNSCEAR) decided to carry out, once sufficient information was available, a full assessment of the levels of exposure and radiation risks attributable to the Fukushima accident. It envisages a preliminary document for consideration at its 59th session in May of 2012 and a more complete report for the 60th session of the Committee in 2013. This paper summarises the aims and objectives of the project, the scope, the working arrangements as well as the relation of the work to other activities. (note)