Assessment of radon equilibrium factor from distribution parameters of simultaneous radon and radon progeny measurements

In Canada, a radon and radon progeny survey was carried out in the 1970s in 19 cities. To the authors’ knowledge, this is the only large survey of simultaneous radon and radon progeny measurements up to the present time. However, the survey was carried out for the purpose of establishing geographic variation of radon and radon progeny; therefore, radon equilibrium factors, F, were not assessed at that time. From the summary results of this large simultaneous radon and radon progeny survey, the characteristics of radon equilibrium factor were assessed. The average F factor assessed from this survey in 12,576 houses is 0.54. The current assessment may indicate that the typical F value of 0.4 recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the International Commission on Radiological Protection (ICRP) could lead to a downward bias in the estimation of radon doses to the lung.     

The assessment of the impact of different radon sources into indoor air

The contributions of different radon sources into total indoor radon level can differ in some times depending on geographical and climatic features of the locality, building characteristics, lifestyle and habits of the population. The revealing of most significant radon sources for examined locality and the assessment of their relative contributions will allow planning expected radon levels during building design stage. The analysis of the factors influencing indoor radon levels and the computation of radon enter to dwellings from different sources were carried out in Tomsk. About 200 dwellings were investigated on the radon presence by solid state track detectors. The results of the comparative analysis of the theoretical and experimental sets are discussed in this paper.     

Lung cancer incidence attributable to residential radon exposure in Finland

This study aimed to estimate (1) the number of avoidable lung cancer cases attributable to residential radon in Finland in 2017, separately by age, sex, dwelling type and smoking status, (2) the impact of residential radon alone and the joint effect of residential radon and smoking on the number of lung cancers and (3) the potential decrease in the number of radon-attributable lung cancers if radon concentrations exceeding specified action levels (100, 200 and 300 Bq m^?3) would have been mitigated to those levels. Population-based surveys of radon concentrations and smoking patterns were used. Observed radon levels were contrasted with 25 Bq m^?3 representing a realistic minimum level of exposure. Lung cancer risk estimates for radon and smoking were derived from literature. Lastly, the uncertainty due to the estimation of exposure and risk was quantified using a computationally derived uncertainty interval. At least 3% and at most 8% of all lung cancers were estimated as being attributable to residential radon. For small cell carcinoma, the proportion of cases attributable to radon was 8–13%. Among smokers, the majority of the radon-related cases were attributable to the joint effect of radon and smoking. Reduction of radon exposure to 100 Bq m^?3 action level would eliminate approximately 30% of radon-attributable cases. Estimates were low compared with the literature, given the (relatively high) radon levels in Finland. This was mainly due to the lower radon levels and higher smoking prevalence in flats than in houses and a more realistic point of comparison, factors which have been ignored in previous studies. The results can guide actions in radon protection and in prevention of lung cancers.

     

Suppression of atopic dermatitis and tumor metastasis in mice by small amounts of radon

We examined the effect of radon in two experimental disease models in mice by administering radon dissolved in water at 68-203 Bq/liter. Administration of radon in drinking water to NC/Nga mice significantly delayed the progression of atopic dermatitis-like skin lesions induced by picrylchloride when administered prior to the induction of disease signs. The number of pulmonary metastatic foci in C57BL/6 mice inoculated with B16 melanoma cells was also reduced significantly by administration of radon in drinking water when the number of tumor cells was small and the radon treatment was started prior to tumor inoculation. The ratio of Ifng to Il4 produced by splenocytes from BALB/c mice immunized with DNP-Ascaris was significantly increased by administration of radon in drinking water. From these results, a modulation of immunity by radon was suggested.     

Quantitative health impact of indoor radon in France

Radon is the second leading cause of lung cancer after smoking. Since the previous quantitative risk assessment of indoor radon conducted in France, input data have changed such as, estimates of indoor radon concentrations, lung cancer rates and the prevalence of tobacco consumption. The aim of this work was to update the risk assessment of lung cancer mortality attributable to indoor radon in France using recent risk models and data, improving the consideration of smoking, and providing results at a fine geographical scale. The data used were population data (2012), vital statistics on death from lung cancer (2008–2012), domestic radon exposure from a recent database that combines measurement results of indoor radon concentration and the geogenic radon potential map for France (2015), and smoking prevalence (2010). The risk model used was derived from a European epidemiological study, considering that lung cancer risk increased by 16% per 100 becquerels per cubic meter (Bq/m³) indoor radon concentration. The estimated number of lung cancer deaths attributable to indoor radon exposure is about 3000 (1000; 5000), which corresponds to about 10% of all lung cancer deaths each year in France. About 33% of lung cancer deaths attributable to radon are due to exposure levels above 100 Bq/m³. Considering the combined effect of tobacco and radon, the study shows that 75% of estimated radon-attributable lung cancer deaths occur among current smokers, 20% among ex-smokers and 5% among never-smokers. It is concluded that the results of this study, which are based on precise estimates of indoor radon concentrations at finest geographical scale, can serve as a basis for defining French policy against radon risk.     

Alkaline single cell gel electrophoresis and human biomonitoring for genotoxicity: a study on subjects with residential exposure to radon.

Based on theoretical estimates and various correlation studies, it has been suggested that ingestion of radon in drinking water represents an increased risk for cancer. Such a risk has never been conclusively shown in epidemiological or experimental animal studies, however, and it has been questioned whether the radon level in the drinking water is of any significance in terms of overall radon exposure. Using primary DNA damage as a biological marker for an ongoing exposure to ionising radiation, the present study was undertaken to investigate whether people with different types of residential radon exposures differed with regard to their levels of DNA damage in circulating lymphocytes. DNA damage was measured in coded blood samples from 125 residents living in 45 households with different levels of radon-222 in the drinking water (10-2410 Bq/l) and indoor air (35-1025 Bq/m3) using alkaline single cell gel electrophoresis (the 'Comet' assay). Increased levels of radon in indoor air (>200 Bq/m3) were found to be associated with an increased level of DNA damage in peripheral lymphocytes (P相似文献   

Radon, smoking and lung cancer risk: results of a joint analysis of three European case-control studies among uranium miners

A combined analysis of three case-control studies nested in three European uranium miner cohorts was performed to study the joint effects of radon exposure and smoking on lung cancer death risk. Occupational history and exposure data were available from the cohorts. Smoking information was reconstructed using self-administered questionnaires and occupational medical archives. Linear excess relative risk models adjusted for smoking were used to estimate the lung cancer risk associated with radon exposure. The study includes 1046 lung cancer cases and 2492 controls with detailed radon exposure data and smoking status. The ERR/WLM adjusted for smoking is equal to 0.008 (95% CI: 0.004-0.014). Time since exposure is shown to be a major modifier of the relationship between radon exposure and lung cancer risk. Fitting geometric mixture models yielded arguments in favor of a sub-multiplicative interaction between radon and smoking. This combined study is the largest case-control study to investigate the joint effects of radon and smoking on lung cancer risk among miners. The results confirm that the lung carcinogenic effect of radon persists even when smoking is adjusted for, with arguments in favor of a sub-multiplicative interaction between radon and smoking.     

Toxin or medicine? Explanatory models of radon in Montana health mines

Environmental protection and public health agencies in the United States and elsewhere label radioactive radon gas a toxic environmental hazard and a major cause of lung cancer. Paradoxically, in Europe and Japan radon gas is also used as an analgesic and anti-inflammatory, as one choice in the spectrum of conventional medical care. Although it is possible to find radon therapy in the United States, it exists only as an unconventional practice in Montana "radon health mines." In this article, I examine the use of radon therapy by Americans despite intensive public health education media campaigns. Using the notion of explanatory models as an analytical framework, I argue that American health mine clients adjust or replace "toxic models" of radon with new kinds of explanatory models that allow radon to be redefined as a healing substance. The manner of this adjustment varies according to peoples' individual needs, their own preexisting cultural models and experiences, and their individual personalities; the source of authoritative knowledge accepted by each person is a strong influence. Through these altered explanatory models, mine clients are able to view their use of radon therapy as a rational course of action.     

Radon and uranium concentrations in drinking water sources along the fault line passing through Reasi district,lesser Himalayas of Jammu and Kashmir State,India

The presence of radon in drinking water causes radiation-related health hazards both through inhalation and ingestion. In the present study, 28 drinking water samples from natural flowing springs, freshwater ponds, and deep hand pumps were analyzed in the fault zone of Reasi region of Jammu &; Kashmir. Radon measurement was performed using the RAD7 electronic device for radon content determination. Average mean values of these samples vary from 2.80 ± 0.78 to 74.37 ± 2.76 Bq l^?1. Nineteen drinking water samples analyzed have radon levels in excess of USEPA recommended maximum contamination level of 11.1 Bq l^?1. The annual effective dose from radon in water due to its ingestion and inhalation per individual has also been calculated. Uranium concentration in these water samples was also analyzed for a possible correlation between different types of rocks and values of radon in water. Results obtained have been compared with the results of earlier investigators for mean radon concentration and mean annual effective dose for radon in water from different regions of northern India and Pakistan. It has been found that radon levels in a significant number of water samples collected from the region of fault line are higher than USEPA recommendations. A positive correlation is observed between the depth of the water source and the values of radon levels in water samples collected from these sources. Measurements of radon concentration in these water samples were also performed with a Smart Radon Monitor designed by Bhabha Atomic Research Centre, Trombay, Mumbai, India, for a comparative analysis.     

Radon progeny activity in sweat following radon exposure in a warm and humid environment

The objective was to evaluate whether activity of radon progenies can be detected in sweat following speleotherapeutic radon exposure (40 kBq/m³) in a warm (38°C) and humid (relative humidity >70%) environment. A group of 11 male patients with spondyloarthropathy (n=6) or non-inflammatory rheumatic diseases (n=5) underwent a 1-h treatment in the gallery of the Gasteiner Heilstollen, and 20 min after leaving the treatment area radon progeny activity was measured in sweat by utilizing a special filter set. The results suggest that radon is discharged with sweat, causing a significant activity of radon and radon progenies on the skin. This finding may be important from a clinical point of view, since specialists experienced in radon therapy have repeatedly emphasized the importance of the degree of radioactivity on the skin for the effectiveness of treatment. It has even been claimed that the skin is the major target for radon therapy, possibly because of the influence on Langerhans’ cell function. Received: 23 August 1999 / Accepted: 1 February 2000     

Factors determining the formation of radon levels inside buildings

The theoretical and experimental investigation of radon levels inside dwellings of Tomsk was carried out. The statistical analysis of gathered results let us to reveal the significant factors, which define the formation of radon levels inside the buildings and dependencies of radon distribution. The significant factors are: building type (urban or rural), year season, floor level (is significant only for buildings of rural type), daytime and social factor includes habits and life stile of inhabitants. The distribution of mean radon levels in buildings obeys the log-normal law. The distribution of radon level among the floors for urban type of buildings obeys the normal law, for rural type of buildings--exponential law.     

Radon in dwellings: The importance of ventilation

Summary People who live in industrial countries receive a radioactive dose of 2.4 mSv/y: the most important contribution to this dose is given by radon decay products. Radon is a noble gas generated from the disintegration of radium, which is found in soils and building materials. Owing to a bad air circulation, radon and its daughters may accumulate in a house. By using a mathematical model it may be shown that radon concentration is inversely proportional to the ventilation rate. Measurements of radon concentration through the method of activated carbon canisters, show that in a room with a double-pane window, kept continuously closed, the mean radon concentration can exceed the concentration of a similar room with a single-pane window of 190%. However, the radon concentration inside the energy-saving room may be decreased up to values slightly higher than those measured in the conventional window room, by simply opening the double-pane window a few minutes a day. A set of measurements carried out in a group of house in Reggio Emilia validates the effectiveness of that practice: radon concentrations in rooms with double-pane window closely approximated to those of rooms with ordinary window.     

Criteria for the assessment of radon potential risk in territories

The detailed analysis of criteria used in the different countries for an assessment of radon potential risk in territories was made. Such criteria as radon flux density from earth surface, radon concentration in soil air, specific activity of 226Ra in superficial soils were chosen. The analysis has revealed that the most reliable criterion is the value of equilibrium radon concentration in the soil air. The method of measurement of this value is specified.     

Lung cancer and indoor radon exposure in the north of Portugal--an ecological study

BackgroundIndoor radon exposure is a well documented environmental factor as a leading cause of lung cancer. Objectives: The aim of this study was to assess the risk of lung cancer and estimate the number of deaths due to indoor radon exposure in the north of Portugal, between 1995 and 2004. Methods: The sixth Biological Effects of Ionizing Radiation Committee (BEIR VI) preferred models were applied to estimate the risk of developing lung cancer induced by indoor radon exposure, by age and level of exposure, and calculated the number of lung cancer deaths attributable to this exposure. Lung cancer mortality data were granted by the North Regional Health Administration and indoor radon concentrations resulted from a national survey conducted by the Portuguese Environmental Agency. The smoking habit was accounted with two methods. A submultiplicative interaction between smoking and indoor radon exposure was considered. Results: Depending on the model applied and the method used to account for the smoking habit, the estimated number of lung cancer deaths attributed to indoor radon exposure, in northern Portugal, ranges from 1565 to 2406, for the period between 1995 and 2004. This indicates that of the 8514 lung cancer deaths observed, from 18 to 28% could be associated with indoor radon exposure.ConclusionsThis was the first study realized in Portugal on the impact of indoor radon exposure in lung cancer mortality. The application of the BEIR VI models led to a high number of lung cancer deaths due to indoor radon exposure.     

Adjusting lung cancer risks for temporal and spatial variations in radon concentration in dwellings in Gansu Province, China

Our recent study in Gansu Province, China reported an increasing risk of lung cancer with increasing residential radon concentration that was consistent with previous pooled analyses and with meta-analyses of other residential studies (Wang et al., Am. J. Epidemiol. 155, 554-564, 2002). Dosimetry used current radon measurements (1-year track-etch detectors) in homes to characterize concentrations for the previous 30 years, resulting in uncertainties in exposure and possibly reduced estimates of disease risk. We conducted a 3-year substudy in 55 houses to model the temporal and spatial variability in radon levels and to adjust estimates of radon risk. Temporal variation represented the single largest source of uncertainty, suggesting the usefulness of multi-year measurements to assess this variation; however, substantial residual variation remained unexplained. The uncertainty adjustment increased estimates of the excess odds ratio by 50-100%, suggesting that residential radon studies using similar dosimetry may also underestimate radon effects. These results have important implications for risk assessment.     

Indoor radon and lung cancer. Estimating the risks.

Radon is ubiquitous in indoor environments. Epidemiologic studies of underground miners with exposure to radon and experimental evidence have established that radon causes lung cancer. The finding that this naturally occurring carcinogen is present in the air of homes and other buildings has raised concern about the lung cancer risk to the general population from radon. I review current approaches for assessing the risk of indoor radon, emphasizing the extrapolation of the risks for miners to the general population. Although uncertainties are inherent in this risk assessment, the present evidence warrants identifying homes that have unacceptably high concentrations.     

Basic study on radon effects and thermal effects on humans in radon therapy

Because most of the diseases to which radon (222Rn) therapy is applied are related to activated oxygen, in this study the effect of the radioactivity of radon and the thermal effect were compared under a room or a hot spring condition with the same chemical component using as the parameters the activity of superoxide dismutase (SOD), which is an oxidation inhibitor, and lipid peroxide and low density lipoprotein (LDL)-cholesterol, which are closely involved in arteriosclerosis. Results show that the SOD activity was significantly increased, and the lipid peroxide and LDL-cholesterol levels were significantly decreased on days 6 and 7 of study. The results were about 2-fold larger in the radon group than in the thermo group. This suggests that the anti-oxidation function was more enhanced by radon therapy than by thermo therapy, and suggests that radon therapy may help to prevent the causes of life style-related diseases such as arteriosclerosis. These findings are important in understanding the mechanism of diseases in which radon therapy is used as treatment, and most of which are called activated oxygen-related diseases.     

Dosimetric assessment of radon in a vegetable system

An alpha-dose calculation due to radon uptake in anthers of Tradescantia, clone 4430, has been performed. Probability distribution density of the dose in the pollen mother cells was calculated by means of a model that simulates the interaction of separate alpha-particles with these cells. It is shown that alpha-radiation from either radon or its decay products surrounding the buds does not reach pollen mother cells because of the short-range alpha-particles. However, it is suggested that radon diffuses through the gap structure of the bud to the anther from which a radon-gas adsorption process takes place. Absorbed-dose calculations in the anther are discussed as well as their relationship to the experimental results of micronucleus induction in pollen mother cells. The radon concentration interval used (0.85 kBq m(-3)-98.16 kBq m(-3)) is equivalent to the exposure to an average environmental radon concentration (40 Bq m(-3)) for 2.3 months or 22.1 years, respectively. The lowest radon concentration to induce micronuclei was 12.1 kBq m(-3), which is 15 times in excess of that adopted for old buildings in Canada.     

Radon in Norwegian dwellings and the feasibility of epidemiological studies

Summary The results of a pilot study on radon in Norwegian dwellings are presented together with a discussion on the feasibility of an epidemiological study on the correlation between lung cancer and radon progeny exposure in dwellings. There are large variations in the mean radon concentration in Norwegian municipalities, and the population average indoor radon concentration is high (80–100 Bq m^–3). The large variations and high absolute values, together with excellent lung cancer and smoking habit data, make it feasible to conduct epidemiological studies based on representative exposure data in the Norwegian population.