Radon Inhalation Research Articles

STUDY OF 222RN CONTINUOUS MONITORING TIME SERIES AND DOSE ASSESSMENT IN SIX EUROPEAN CAVES.

The present work aims to assess the effective doses from long-term continual radon monitoring in six European caves (Slovenia, Slovakia and the Czech Republic), including influencing environmental factors. Caves are important radiation protection subjects because of elevated radon activity concentration (~kBq/m3), mostly due to the low natural ventilation. The sources of radon gas are most often underground rock layers and clastic sediments. The radon activity concentrations show seasonal variations, for which the outside temperature is the main driving force. The human health impact due to the radon inhalation in monitored caves was estimated through the annual effective dose, using the methodology provided by the International Commission on Radiological Protection (ICRP Publication 137). The annual effective dose could reach several tens of mSv, depending on the working hours spent in the underground.

Repeated radon exposure induced lung injury and epithelial–mesenchymal transition through the PI3K/AKT/mTOR pathway in human bronchial epithelial cells and mice

Radon exposure is the most frequent cause of lung cancer in non-smokers. The high linear energy transfer alpha-particles from radon decay cause the accumulation of multiple genetic changes and lead to cancer development. Epithelial–mesenchymal transition (EMT) plays an important role in oncogenesis. However, the mechanisms underlying chronic radon exposure-induced EMT attributed to carcinogenesis are not understood. This study aimed to explore the EMT and potential molecular mechanisms induced by repeated radon exposure. The EMT model of 16HBE and BEAS-2B cells was established with radon exposure (20000 Bq/m3, 20 min each time every 3 days). We found repeated radon exposure facilitated epithelial cell migration, proliferation, reduced cell adhesion and ability to undergo EMT through a decrease in epithelial markers and an increase in mesenchymal markers. Radon regulated the expression of matrix metalloproteinase 2 (MMP2) and tissue inhibitors of metalloproteinase 2 (TIMP2) to disrupt the balance of MMP2/TIMP2. In vivo, BALB/c mice were exposed to 105 Bq/m3 radon gas for cumulative doses of 60 and 120 Working Level Months (WLM). Radon inhalation caused lung damage and fibrosis in mice, which was aggravated with the increase of exposure dose. EMT-like transformation also occurred in lung tissues of radon-exposure mice. Moreover, radon radiation increased p-PI3K, p-AKT and p-mTOR in cells and mice. Radon reduced the GSK-3β level and elevated the active β-catenin in 16HBE cells. The m-TOR and AKT inhibitors attenuated radon exposure-induced EMT by regulation related biomarkers. These data demonstrated that radon exposure induced EMT through the PI3K/AKT/mTOR pathway in epithelial cells and lung tissue.

Radon measurements in water galleries in Tenerife, Canary Islands (Spain)

Water galleries are one of the main systems for capturing groundwater on the western islands of the Canary Islands (Spain). Water galleries are approximately 2-m high × 2-m wide excavated, sub-horizontal drains. This research focuses on taking measurements of radon, a natural radioactive gas present in volcanic territories, such as the Canary Islands, which may cause health problems for workers inside water galleries. The aim of the research is to evaluate radon gas activity as a natural risk in a selected group of water galleries of Tenerife by means of officially approved radon passive detector devices. It was observed that in all the galleries studied, the radon gas concentration values were exceeded by a wide margin, which makes it a factor to be monitored in gallery workers, due to the proven association between radon inhalation and lung cancer.

Calculating the indoor radon flux from construction materials and soil

A theoretical method is used to calculate the radon exhalation and flux from the walls of a room and the soil to the living space in the room. The calculations are based on the Fick’s laws to describe the radon diffusion through the walls and in the soil. In both cases, the diffusion is considered as one-dimension along the direction to the inside of the room. Under some conditions, the three-dimensional diffusion has to be taken into account. A comparison between the one- and three-dimensional descriptions is discussed, and hence the radon areal release rate from a wall and that from a construction material sample are formulated and related. Consequent indoor radon concentrations and inhalation doses are represented. The effect of the radon release from the construction materials on calculating the gamma dose rate in a room is studied.

Estimation of Occupational Exposure during Ceramic Manufacturing

Introduction: The present study investigated the relatively high concentrations of natural radionuclides in raw material that used in ceramic manufacturing, and estimated the occupational exposure due to these activity concentrations. Material and Methods: A high-purity Germanium detector was used to determine naturally occurring radionuclides in raw materials that used in ceramic manufacturing. Activity concentrations of these materials lead to potential radiological hazards due to gamma and alpha radiation. These hazards were evaluated in the present study. Results: Maximum activity concentrations was5844, 1065 and 41 Bq/kg for 226Ra, 232Th and 235U in powdered quartz; however, maximum activity concentration for 40K was 1868 Bq/kg in colors. These activities were observed to be exceeding the exemption limit. Pancreasreceived the lowest dose (i.e., 0.02 mSv/y), while skin received the highest dose (i.e., 0.044mSv/y). Internal hazard index (Hin) was reported as 53.74, which exceed the recommended value (Hin≤1). Alpha index was 42.4 which led to over exposure. Representative level index and excess lifetime cancer risk were 0.00062 and 0.641 respectively. The total annual external dose was 2.62 m Gy/y which led to 1.83 mSv/y effective dose. Radiological hazard due to radon inhalation was 1.53E-06 mSv/y. Conclusion: Due to the high activity concentrations of raw materials (especially zirconium compounds) and consequently the associated high dose, specific regulations must be applied in the ceramic industry in Egypt.

X-Irradiation at 0.5Gy after the forced swim test reduces forced swimming-induced immobility in mice.

The forced swim test (FST) is a screening model for antidepressant activity; it causes immobility and induces oxidative stress. We previously reported that radon inhalation has antidepressant-like effects in mice potentially through the activation of antioxidative functions upon radon inhalation. This study aimed to investigate the effect of prior and post low-dose X-irradiation (0.1, 0.5, 1.0 and 2.0Gy) on FST-induced immobility and oxidative stress in the mouse brain, and the differences, if any, between the two. Mice received X-irradiation before or after the FST repeatedly for 5 days. In the post-FST-irradiated group, an additional FST was conducted 4h after the last irradiation. Consequently, animals receiving prior X-irradiation (0.1Gy) had better mobility outcomes than sham-irradiated mice; however, their levels of lipid peroxide (LPO), an oxidative stress marker, remained unchanged. However, animals that received post-FST X-irradiation (0.5Gy) had better mobility outcomes and their LPO levels were significantly lower than those of the sham-irradiated mice. The present results indicate that 0.5Gy X-irradiation after FST inhibits FST-induced immobility and oxidative stress in mice.

MEAN VALUE OF LET FOR ONCOGENIC EFFECTS OF RADON AND ITS PROGENY

The topic of the article is to define the average value of linear energy transfer (LET) for carcinogenic effects of radon progeny. The microdosimetric model of boundary specific energy is used. It follows that the effect at high LET should decrease approximately with the third power of LET. This is verified by the analysis of the relationship between radiation effects ratio and LET in published experiments with oncogenic transformation of mammalian cells irradiated with the monoenergetic alpha particles. If these cells are exposed with the radon irradiator, our analysis leads us to conclude that the oncogenic effect of radon progeny is comparable to that of alpha particles with a LET of 75keV/μm. It is about a quarter lower than the LET value, where the effect of the monoenergetic alpha particles reaches its maximum level. Some implications for lung cancer due to radon inhalation may also be carefully examined.

Radon Therapy Is Very Promising as a Primary or an Adjuvant Treatment for Different Types of Cancers: 4 Case Reports.

We report on the application of radon inhalation therapy to patients with 4 types of cancer: colon, uterine, lung, and liver cell. The radon treatments were given to improve the efficacy of chemotherapy and were potent in all 4 cases. Marker values decreased and disease symptoms were alleviated. We include a lengthy discussion on the mechanism that may be responsible for the observed results. While employing the radon generator to treat the patient with hepatocellular carcinoma, we discovered that a concentration of 6 MBq/m3 was very effective, while 1 MBq/m3 was marginal. This implies different, and rather high, radon concentration thresholds for the treatment of different types of cancer. The evidence from these 4 cases suggests that radon inhalation may be beneficial against various cancer types as an important adjuvant therapy to conventional chemotherapy and for local high-dose radiotherapy, which would address the problem of distant metastasis. A previous case report on 2 patients with advanced breast cancer, who refused chemotherapy or radiotherapy, indicates that radon may be effective as a primary therapy for cancer. Clinical trials should be carried out to determine the best radon concentrations for treatment of other types of cancer, at different stages of progression.

Radon survey in the kindergartens of three Visegrad countries (Hungary, Poland and Slovakia)

The radon activity concentration was measured in 67 rooms in kindergartens in Visegrad countries over a period of 1 year using the SSNTD method within the framework of the standard V4 project. In 7.5% of rooms radon activity concentration exceeded 300 Bq m−3, the reference value recommended by the Council Directive 2013/59/EURATOM. The annual effective doses due to radon inhalation ranged from 0.5 to 13.3 mSv for children and from 0.3 to 8.3 mSv for staff.

Assessment of radiation dose from radon ingestion and inhalation in commercially bottled drinking water and its annual effective dose in Eastern Province, Saudi Arabia

ABSTRACTThe isotopes of radium, uranium, polonium, lead, and short-lived radon are the common radionuclides found in drinking water. The abnormal amount of radon in drinking water causes health risks. In this study, an attempt has been made to estimate the level of radon concentrations and its annual effective dose from bottled water brands and tap drinking water. A total of 77 samples of drinking water sources; 47 bottled water brands and 27 tap water samples including 3 samples from water storage tank supplier were collected and examined. The measurements were performed using active detection method technique called Durridge RAD7-H2O with closed loop. The minimum and maximum level of average radon concentrations was 0.10 ± 0.02 BqL−1 and 9.2 ± 0.02 BqL−1. The results were below the limit recommended by the Environmental Protection Agency (11 BqL−1). The annual effective dose for children and adults was in the range from almost 0.51 µSvy−1 to 46.69 µSvy−1. There are no indications of significant threat from radon concentrations in bottled water brands or tap drinking water, and it is safe as far as health hazard is concerned.

Comparative Effects of Radon Inhalation According to Mouse Strain and Cisplatin Dose in a Cisplatin-induced Renal Damage Model

Comparative Effects of Radon Inhalation According to Mouse Strain and Cisplatin Dose in a Cisplatin-induced Renal Damage Model

Characterization of radon levels in soil and groundwater in the North Maladeta Fault area (Central Pyrenees) and their effects on indoor radon concentration in a thermal spa

Radon levels in the soil and groundwater in the North Maladeta Fault area (located in the Aran Valley sector, Central Pyrenees) are analysed from both geological and radiation protection perspectives. This area is characterized by the presence of two important normal faults: the North Maladeta fault (NMF) and the Tredós Fault (TF). Two primary aspects make this study interesting: (i) the NMF shows geomorphic evidence of neotectonic activity and (ii) the presence of a thermal spa, Banhs de Tredós, which exploits one of the several natural springs of the area and needs to be evaluated for radiation dosing from radon according to the European regulation on basic safety standards for protection against ionizing radiation. The average soil radon and thoron concentrations along a profile perpendicular to the two normal faults — 22 ± 3 kBq·m−3 and 34 ± 3 kBq·m−3, respectively — are not high and can be compared to the radionuclide content of the granitic rocks of the area, 25 ± 4 Bq·kg−1 for 226Ra and 38 ± 2 Bq·kg−1 for 224Ra. However, the hypothesis that the normal faults are still active is supported by the presence of anomalies in both the soil radon and thoron levels that are unlikely to be of local origin together with the presence of similar anomalies in CO2 fluxes and the fact that the highest groundwater radon values are located close to the normal faults. Additionally, groundwater 222Rn data have complemented the hydrochemistry data, enabling researchers to better distinguish between water pathways in the granitic and non-granitic aquifers. Indoor radon levels in the spa vary within a wide range, [7–1664] Bq·m−3 because the groundwater used in the treatment rooms is the primary source of radon in the air. Tap water radon levels inside the spa present an average value of 50 ± 8 kBq·m−3, which does not exceed the level stipulated by the Spanish Nuclear Safety Council (CSN) of 100 kBq·m−3 for water used for human consumption. This finding implies that even relatively low radon concentration values in water can constitute a relevant indoor radon source when the transfer from water to indoor air is efficient. The estimated effective dose range of values for a spa worker due to radon inhalation is [1–9] mSv·y−1. The use of annual averaged radon concentration values may significantly underestimate the dose in these situations; therefore, a detailed dynamic study must be performed by considering the time that the workers spend in the spa.

RADON CONCENTRATION IN THE AREA OF WASTE ROCK DUMPS, BROD, CR-CASE STUDY.

There are ~7000 mining waste storage facilities including waste rock dumps in the Czech Republic. One of the radiation protection present subjects is a health impact estimation of the huge mass of material in waste rock dumps left after uranium mining. In this document are presented selected results of waste rock dump long-term monitoring in the area of shaft No. 15 (Pribram, CR) and its estimated health impact to the representative person in a village Brod. The external irradiation was estimated based on in situ gamma spectrometry measurement results and on a Monte Carlo model and it turned out to be negligible (tens μSv), while the internal irradiation (RAMARN, ALGADE Environmental and RAMONIS detection systems) is more significant. The estimated total annual effective dose for representative person is mainly caused by indoor radon inhalation. The maximum outdoor radon concentration in summer season was measured during night hours between 9 p.m. and 7 a.m. and could reach thousands Bq/m3. The average indoor concentration measured in randomly selected houses was 450 Bq/m3. The radon exhalation rate was 35-40 mBq m-2 s-1.

Radon inhalation induces manganese-superoxide dismutase in mouse brain via nuclear factor-κB activation.

Although radon inhalation increases superoxide dismutase (SOD) activities in mouse organs, the mechanisms and pathways have not yet been fully clarified. The aim of this study was to determine the details of SOD activation in mouse brain tissue following the inhalation of radon at concentrations of 500 or 2000 Bq/m3 for 24 h. After inhalation, brains were removed quickly for analysis. Radon inhalation increased the manganese (Mn)-SOD level and mitochondrial SOD activity. However, the differences were not significant. There were no changes in the Cu/Zn-SOD level or cytosolic SOD activity. Radon inhalation increased the brain nuclear factor (NF)-κB content, which regulates the induction of Mn-SOD, in the nuclear and cytosolic compartments. The level of inhibitor of nuclear factor κB kinase subunit β (IKK-β), which activates NF-κB, was slightly increased by radon inhalation. The expression of cytoplasmic ataxia-telangiectasia mutated kinase in mice inhaling radon at 500 Bq/m3 was 50% higher than in control mice. In addition, NF-κB–inducing kinase was slightly increased after inhaling radon at 2000 Bq/m3. These findings suggest that radon inhalation might induce Mn-SOD protein via NF-κB activation that occurs in response to DNA damage and oxidative stress.

Protective effects of hot spring water drinking and radon inhalation on ethanol-induced gastric mucosal injury in mice.

ABSTRACTRadon therapy using radon (222Rn) gas is classified into two types of treatment: inhalation of radon gas and drinking water containing radon. Although short- or long-term intake of spa water is effective in increasing gastric mucosal blood flow, and spa water therapy is useful for treating chronic gastritis and gastric ulcer, the underlying mechanisms for and precise effects of radon protection against mucosal injury are unclear. In the present study, we examined the protective effects of hot spring water drinking and radon inhalation on ethanol-induced gastric mucosal injury in mice. Mice inhaled radon at a concentration of 2000 Bq/m3 for 24 h or were provided with hot spring water for 2 weeks. The activity density of 222Rn ranged from 663 Bq/l (start point of supplying) to 100 Bq/l (end point of supplying). Mice were then orally administered ethanol at three concentrations. The ulcer index (UI), an indicator of mucosal injury, increased in response to the administration of ethanol; however, treatment with either radon inhalation or hot spring water inhibited the elevation in the UI due to ethanol. Although no significant differences in antioxidative enzymes were observed between the radon-treated groups and the non-treated control groups, lipid peroxide levels were significantly lower in the stomachs of mice pre-treated with radon or hot spring water. These results suggest that hot spring water drinking and radon inhalation inhibit ethanol-induced gastric mucosal injury.

AN ESTIMATION OF THE EXPOSURE OF THE POPULATION OF ISRAEL TO NATURAL SOURCES OF IONIZING RADIATION.

The radiation dose to the population of Israel due to exposure to natural sources of ionizing radiation was assessed. The main contributor to the dose is radon that accounts for 60% of the exposure to natural sources. The dose due to radon inhalation was assessed by combining the results of a radon survey in single-family houses with the results of a survey in apartments in multi-storey buildings. The average annual dose due to radon inhalation was found to be 1.2 mSv. The dose rate due to exposure to cosmic radiation was assessed using a code that calculates the dose rate at different heights above sea level, taking into account the solar cycle. The annual dose was calculated based on the fraction of time spent indoors and the attenuation provided by buildings and was found to be 0.2 mSv. The annual dose due to external exposure to the terrestrial radionuclides was similarly assessed. The indoor dose rate was calculated using a model that takes into account the concentrations of the natural radionuclides in building materials, the density and the thickness of the walls. The dose rate outdoors was calculated based on the concentrations of the natural radionuclides in different geological units in Israel as measured in an aerial survey and measurements above ground. The annual dose was found to be 0.2 mSv. Doses due to internal exposure other than exposure to radon were also calculated and were found to be 0.4 mSv. The overall annual exposure of the population of Israel to natural sources of ionizing radiation is therefore 2 mSv and ranges between 1.7 and 2.7 mSv.

Analysis of liver damage from radon, X-ray, or alcohol treatments in mice using a self-organizing map.

In our previous studies, we found that low-dose radiation inhibits oxidative stress–induced diseases due to increased antioxidants. Although these effects of low-dose radiation were demonstrated, further research was needed to clarify the effects. However, the analysis of oxidative stress is challenging, especially that of low levels of oxidative stress, because antioxidative substances are intricately involved. Thus, we proposed an approach for analysing oxidative liver damage via use of a self-organizing map (SOM)—a novel and comprehensive technique for evaluating hepatic and antioxidative function. Mice were treated with radon inhalation, irradiated with X-rays, or subjected to intraperitoneal injection of alcohol. We evaluated the oxidative damage levels in the liver from the SOM results for hepatic function and antioxidative substances. The results showed that the effects of low-dose irradiation (radon inhalation at a concentration of up to 2000 Bq/m3, or X-irradiation at a dose of up to 2.0 Gy) were comparable with the effect of alcohol administration at 0.5 g/kg bodyweight. Analysis using the SOM to discriminate small changes was made possible by its ability to ‘learn’ to adapt to unexpected changes. Moreover, when using a spherical SOM, the method comprehensively examined liver damage by radon, X-ray, and alcohol. We found that the types of liver damage caused by radon, X-rays, and alcohol have different characteristics. Therefore, our approaches would be useful as a method for evaluating oxidative liver damage caused by radon, X-rays and alcohol.

Assessment of indoor radon levels in Portuguese thermal spas

The concentration of radon was assessed in the indoor air of 14 thermal spas and in the home of a selected worker from each thermal spa. The measurements of the indoor radon concentration were carried out using CR-39 detectors, placed in both the workplaces and workers’ homes, exposed for an average period of 45 days, in different seasons of the year. For the thermal spas, the indoor radon concentration ranged between 73 and 4335 Bq m -3 , with a geometric mean of 445 Bq m -3 and an arithmetic mean of 687 Bq m -3 , and within the workers’ homes ranged between 68 and 4051 Bq m -3 , with a geometric mean of 410 Bq m -3 and an arithmetic mean of 785 Bq m -3 . The annual effective doses due to radon inhalation were calculated considering two different exposure scenarios for the thermal spas. For the worst-case scenario, assuming that workers do not have job rotation, the values varied between 1 and 31 mSv y -1 , while for an exposure scenario considering job rotation, the calculated dose ranged between 0.6 and 16 mSv y -1 . For workers’ homes, the calculated dose ranged between 2 and 102 mSv y -1 . The results showed that the EU reference level of 300 Bq m -3 (Directive 2013/59/EURATOM) was exceeded in several cases. In 36% of the thermal spas the exposure of the workers is likely to exceed the effective dose of 6 mSv y -1 and in this case, according to the Directive, it should be considered as “a planned exposure situation”.

Assessement of doses to members of the public arising from the use of ornamental rocks in residences

The main pathways to human exposure associated with naturally occurring radionuclides in ornamental rocks are external irradiation and the inhalation of radon. Usually, external doses and risks are assessed by using generic approaches in which the specific properties and use of the material are not considered. Moreover, limited information on radon inhalation dose due to the use of rock is available. The radionuclide concentrations in 180 rock samples reached a wide range of values: for 228Ra from <2 to 530 Bq kg−1, for 226Ra between <5 and 600 Bq kg−1and for 40K varied between 190 and 2797 Bq kg−1. Considering the rock properties, mathematical models, a residential scenario and radionuclide concentrations in the rocks, 222Rn concentrations and inhalation and external doses were estimated to range from 0.1 to 13 Bq m−3, from 0.01 and 0.26 mSv yr−1 and from 0.01 and 0.61 mSv yr−1, respectively. The ventilation and the emanation rates are key parameters for the Rn dose, whereas the location of the receptor significantly affects the external dose. The overestimations of doses and risks by the generic approaches highlight the necessity of considering the properties and use of the materials for those estimations.

Evaluating the protective effects of radon inhalation or ascorbic acid treatment after transient global cerebral ischemic injury in gerbils

ABSTRACTIn this study, we compared the protective effects of radon inhalation and ascorbic acid administration on transient global cerebral ischemic injury in gerbils. Gerbils were treated with radon inhalation (2000 Bq/m3, 24 hours) or ascorbic acid (100, 300, or 500 mg/kg body weight). Then, transient global cerebral ischemia was induced by bilateral occlusion of the common carotid artery. Results showed that the number of damaged neurons was significantly increased in gerbils that underwent ischemia compared with that in control gerbils. However, the number of damaged neurons in gerbils treated with radon or 500 mg/kg of ascorbic acid before ischemia was significantly lower than gerbils who were subjected to ischemia without any pretreatment, and the protective effects of radon inhalation were similar to the effects of administering 500 mg/kg ascorbic acid. The levels of superoxide dismutase (SOD) and total glutathione (t-GSH) in brain tissue were increased to a similar extent by pretreatment with radon inhalation or 500 mg/kg of ascorbic acid. These findings suggested that radon inhalation has a protective antioxidative effect against transient global cerebral ischemic injury similar to 500 mg/kg ascorbic acid treatment.