Thoron Concentrations Research Articles

Assessment of tracheobronchial and lung dose due to radon and thoron inhalation.

The main sources of natural background radiation are radon, thoron and their progeny, which may cause health risks to humans. Keeping in mind the importance of the subject, three samples each from 10 selected residential areas, including the centre of Babylon Governorate, Iraq, and its districts, were collected. Concentration of radon and thoron was measured using solid-state track detectors (CR-39). The arithmetic means of the concentration of radon and thoron were 47.367±19.56 and 133.246±16.585 Bqm-3, respectively; these values are considered safe when compared with the upper reference level of 200-600 Bqm-3 recommended by the International Commission for Radiological Protection (ICRP). The value of the inhalation equivalent dose from radon gas discovered in these areas with rate 37.893 nSv is less than the value of the global average of 1.15 mSv. This indicates that the risks related to inhalation of radon are low as the lung dose rate (DLung), tracheobronchial region (DT-B), annual effective dose (AED) and excess lifetime cancer risk (ELCR) is (1.894 nGyh-1, 22.736 nSv, 0.236 mSvy-1 and 0.835 x10-3), respectively. While the value of the inhalation equivalent dose (IED) from thoron as effective dose to lung DLung, AED and ELCR are equal to (0.133 nSv, 0.167 mSvy-1 and 0.587 x 10-3), respectively. To conclude, the rates in the study area are less than the ICRP recommended level of 3 mSv; therefore, the studied areas are safe from the health risks of inhalation of radon and thoron.

Radiological monitoring and assessment of the radiation situation in the Kungur Ice Cave

This article presents the results of comprehensive radiological studies conducted in 2021 in order to assess the radiation situation in the Kungur Ice Cave (hereinafter referred to as the KIC). Since the cave is a fairly popular sightseeing object, therefore, the safety of both tourists and workers is a key task for scientific study. The radiation safety assessment was carried out taking into account the parameters of the radiation (gamma) background, measurements of radon and thoron concentrations, microclimatic indicators (air temperature, humidity), airflow rate, illumination and calculation of the indicator of a special assessment of working conditions (SAWC). Such comprehensive and detailed studies were conducted in the KIC for the first time, allowing some patterns to be identified and confirmed. For the indicators of gamma-activity and radon concentration, there is a clear dependence on the season of the year, which is directly related to microclimatic indicators, as well as to compliance with the ventilation regulations that have been established in the cave. The applied ventilation modes provide safe values of the radiation background and toron. In the summer months, the average radon content in the cave exceeds the maximum permissible concentrations by a factor of 7, which required calculation of the time of work in the cave. For the first time, special assessment of working conditions has been calculated for Kungur Ice Cave, but only for the winter period. The SAWC is defined for a working group consisting of engineers, workers and guides, taking into account such parameters as temperature, illumination, humidity, severity and intensity of labor and ionizing radiation (radiation background). According to preliminary data, the overall assessment of labor based on all parameters falls under the “harmful” class of conditions.

STL decomposition analysis for anomaly detection in soil radon and thoron concentrations along Chite fault in Aizawl

STL decomposition analysis for anomaly detection in soil radon and thoron concentrations along Chite fault in Aizawl

Effective dose assessment due to inhalation of 222Rn, 220Rn, and their progeny: highlighting the major contribution of thoron in a thoron-prone area in Cameroon.

To assess public exposure to radon, thoron, and their progeny, measurements were conducted in 50 dwellings within the bauxite-rich area of Fongo-Tongo in western Cameroon. Passive integrating radon-thoron discriminative detectors (specifically RADUET) were employed for radon and thoron measurements. Additionally, concentrations of short-lived radon and thoron progeny were estimated using Direct Radon Progeny Sensors (DRPSs) and Direct Thoron Progeny Sensors (DTPSs) based on LR-115 detectors. The findings revealed indoor radon concentrations ranging from 31 to 123Bqm-3 with a geometric mean (GM) of 62Bqm-3, and indoor thoron concentrations ranging from 36 to 688Bqm-3 with a GM of 242Bqm-3. The Equilibrium Equivalent Radon Concentration (EERC) ranged from 3 to 86Bqm-3 with a GM of 25Bqm-3, while the Equilibrium Equivalent Thoron Concentration (EETC) ranged from 1.2 to 12.5Bqm-3 with a GM of 7.6Bqm-3. Notably, all dwellings recorded radon concentrations below 100Bqm-3. Arithmetic means of radon and thoron equilibrium factors were calculated as 0.47 and 0.04, respectively. To assess annual effective doses from radon and thoron inhalation, equilibrium factors were used along with direct measurements of EERC and EETC. The differences observed in annual effective doses were 4.5% for radon and 42.5% for thoron. Furthermore, the contribution of thoron and its decay products to the annual effective dose from radon, thoron, and their progeny ranged from 12 to 94%, with an average contribution of 58%. Thus, this study found that the effective dose due to thoron inhalation in the study area exceeded that due to radon inhalation. It is concluded that, when evaluating radiation doses and health risks, it is crucial to consider both thoron and its progeny alongside radon and its progeny. This underscores the importance of considering direct measurements for accurately estimating radiation doses.

A study of 222Rn/220Rn exhalation rate and indoor 222Rn/220Rn levels in higher Himalayan terrain.

The noble radioactive gas radon and its isotope thoron dominate terrestrial radiation in the indoor environment. These gases eventually disintegrate generating radioactive ions that readily adhere to aerosol particles. This study was conducted in a tectonically active location with significant radon concentrations. The obtained average values of radon mass exhalation and thoron surface exhalation rate from this study are higher than the global average values of 56 mBq kg-1h-1 and 1000 mBq m-2s-1, respectively. As the exhalation rates are higher, naturally the average radon and thoron concentrations are also greater than the worldwide average values of 40 and 10Bqm-3, respectively. No significant correlation was observed between 222Rn and 220Rn exhalation rate and indoor 222Rn/220Rn concentration. The exposure dose due to 222Rn, 220Rn and their progenies shows no significant health risk.

Contribution of Thoron and Its Progeny to the Effective Dose by Inhalation in the Uranium-Thorium Bearing Regions of Mayo Kebbi and Guéra in Chad

Abstract In recent years, technological developments and hypotheses made by some researchers have revealed that the effective inhalation dose from thoron and its progeny was underestimated. This study uses direct measurements to show the significant contribution of thoron progeny to the effective inhalation dose. To achieve this, radon-thoron discriminative detectors (RADUET) and thoron progeny monitors were used for the simultaneous measurement of radon, thoron, and thoron progeny in 150 selected houses in the townships of Bitkine, Mongo, Léré, and Pala in southern Chad. By solid-state detection, concentrations of radon, thoron, and thoron progeny were measured and associated effective doses evaluated. The mean concentrations of radon, thoron, and thoron progeny were 62 (1), 60 (2), and 7.6 (2.1) Bq m−3, respectively. These concentrations are above the corresponding global average values. The equilibrium factor of the thoron varied considerably from one municipality to another. The average total annual effective dose by inhalation was estimated to be 4.23 mSv. The contribution of thoron and its progeny to the total inhalation dose ranged from 5% to 86% with an average of 62%. Considering the above, public exposure to thoron and its associated progeny is a public health concern in a similar way to radon.

Health Impacts of Natural Background Radiation in High Air Pollution Area of Thailand.

Chiang Mai province of Thailand is known for having the highest natural background radiation in the country, as well as being recognized as one of the world's most polluted cities for air quality. This represents the major contributor to the development of lung cancer. This research aims to estimate the comprehensive dose of both internal and external exposure due to natural background radiation and related health perspectives in the highly polluted area of Chiang Mai. The average values of indoor radon and thoron concentrations in 99 houses over 6 months were 40.8 ± 22.6 and 17.8 ± 16.3 Bq/m3, respectively. These results exceed the worldwide value for indoor radon and thoron (40 and 10 Bq/m3), respectively. During burning season, the average values of indoor radon (56.7 ± 20 Bq/m3) and thoron (20.8 ± 20.4 Bq/m3) concentrations were higher than the world-wide averages. The radon concentration in drinking water (56 samples) varied from 0.1 to 91.9 Bq/L, with an average value of 9.1 ± 22.8 Bq/L. Most of the drinking water samples (87%) fell below the recommended maximum contamination limit of 11.1 Bq/L. The average values of natural radionuclide (226Ra, 232Th and 40K) in 48 soil samples were 47 ± 20.9, 77.9 ± 29.7 and 700.1 ± 233 Bq/kg, respectively. All values were higher than the worldwide average of 35, 30 and 400 Bq/kg, respectively. The average value of outdoor absorbed gamma dose rate (98 ± 32.5 nGy/h) exceeded the worldwide average of 59 nGy/h. Meanwhile, the average activity concentrations of 226Ra, 232Th and 40K in 25 plant food samples were 2.7 ± 0.1, 3.2 ± 1.6 and 1000.7 ± 1.9 Bq/kg, respectively. The 40K concentration was the most predominant in plant foods. The highest concentrations of 226Ra, 232Th and 40K were found in Chinese cabbage, celery and cilantro, respectively. The total annual effective dose for residents in the study area varied from 0.6 to 4.3 mSv, with an average value of 1.4 mSv. This indicates a significant long-term public health hazard due to natural background radiation and suggests a heightened radiation risk for the residents. The excess lifetime cancer risk value (5.4) associated with natural background radiation was found to be higher than the recommended value. Moreover, the number of lung cancer cases per year per million average of 25.2 per million persons per year was in the limit range 170-230 per million people. Overall, our results will be used for future decision making in the prevention of lung cancer risk associated with natural background radiation.

Full characterization and calibration of a transfer standard monitor for atmospheric radon measurements

Abstract. In this work, a full characterization of the new user-friendly version of the Atmospheric Radon MONitor (ARMON), used to measure very low activity concentrations of the radioactive radon gas in the outdoor atmosphere, is carried out. The ARMON is based on the electrostatic collection of 218Po+ particles on a semiconductor detector surface. A main advantage of this instrument is that it offers high-resolution alpha-energy spectra, which will allow us to separate radon progeny (210Po, 218Po, and 214Po). The monitor feature may also allow measurements of thoron (220Rn) by collection of 216Po+, although the instrument is not calibrated for this gas. In the paper, the physical principle; the hardware configuration; and the software development of the automatic and remotely controlled ARMON, conceived and constructed within the MAR2EA and the traceRadon projects, are described. The monitor efficiency and its linearity over a wide span of radon concentration activities have been evaluated and tested here using theoretical and experimental approaches. Finally, a complete budget analysis of the total uncertainty of the monitor was also achieved. Results from the application of a simplified theoretical approach show a detection efficiency for 218Po+ of about 0.0075 (Bq m−3)−1 s−1. The experimental approach, consisting of exposing the ARMON at controlled radon concentrations between a few hundreds to a few thousands of becquerels per cubic metre (Bq m−3), gives a detection efficiency for 218Po+ of 0.0057 ± 0.0002 (Bq m−3) s−1. This last value and its independence from the radon levels were also confirmed thanks to a new calibration method which allows us, using low-emanation sources, to obtain controlled radon levels of a few tens of becquerels per cubic metre (Bq m−3). The total uncertainty of the ARMON detection efficiency obtained for hourly radon concentrations above 5 Bq m−3 was lower than 10 % (k= 1). The characteristic limits of the ARMON – being those dependent on the presence of thoron in the sampled air – were also calculated. A detection limit of 0.132 Bq m−3 was estimated in the absence of thoron. At a typical thoron concentration at atmospheric sites of 0.017 min−1, the detection limit was calculated to be 0.3 Bq m−3, but this can be reduced if using a delay volume, obtaining a decision threshold of 0.0045 Bq m−3. Current results may allow us to confirm that the ARMON is suitable to measure low-level radon activity concentrations (1–100 Bq m−3) and to be used as a transfer standard to calibrate secondary atmospheric radon monitors.

Radiological Risk to Inhalation of Thoron Gas from Medical Materials Samples Derived from Medical Plants in Iraq

Pollution by thoron is one of the factors that is harmful to human health. Medical materials, especially those derived from plants, have natural ingredients which are a major source of natural radioactivity, thoron being one of them. Therefore, the presence of harmful radioactivity in these materials is a matter of concern. This study determined the concentrations of thoron (220Rn or radon-220) from 70 samples of medical materials derived from medical plants using a CR-39 detector. Samples are drugs (solid), skin creams, herbs, toothpaste, drugs (liquid), and cosmetic products found in Iraqi pharmacies. Also, radiological risks such as Annual Effective Dose (AED), Excessive Lifetime Cancer Risk (ELCR), and Lung Cancer Case (LCC) due to inhalation of thoron from medical materials samples in pharmacies were calculated. The results show that the results of the thoron concentrations in the samples of medical materials ranged from 1.02 Bq/m3 to 74.53 Bq/m3, with an average value of 18.21 ± 2.00 Bq/m3. The range values of AED, ELCR (×10-3) and LCC (×10-6) were 0.01-0.588 mSv/y, 0.04-2.36, and 0.18-10.58, respectively. It was als found that the thoron concentrations in samples of the present study vary from a minimum of 12.82 Bq/m3 in cosmetic products samples to a maximum of 30.29 Bq/m3 in herbs samples. Nonetheless, all thoron and radiological risk values were lower than the acceptable world limit (thoron = 200-300 Bq/m3 by ICRP and AED = 1.1-4.4 mSv/y by UNSCEAR).

Radon, Thoron and Polonium Concentrations Estimated in Building Materials Samples Collected from Al-Shatra, Dhi-Qar, Iraq

Radon, Thoron and their short-lived daughters have a high contribution to background radiation, as long-term exposure causes the risk of lung cancer. In current study, five types of building materials with a total 55 samples in Al-Shatra City, Dhi-Qar Governorate, Iraq collected to measure the radon and thoron concentration by using CR-39 solid state nuclear track detector. The results showed that the average radon concentrations in all samples were (103.53±55.94) Bqm−3, while the average thoron concentration was (53.20±44.69) Bqm−3. On the other hand, the annual effective dose of radon ranged between (0.85-6.46) msvy−1, with an average of 2.61msvy−1. While, for thoron concentration was ranged between (0.12-3.28) msvy−1, with an average of 1.49 msvy−1. The annual effective dose was found acceptable limit (3-10 msvy−1) recommended by the International Commission on Radiological Protection (ICRP). On the other side, the average Polonium concentrations (218Po, 214Po) have been found to be 2.053 KBqm−3, 0.866 KBqm−3, respectively.

Comparative study of the radon and thoron concentrations in the indoor environment of the Budhakedar region of the Garhwal Himalaya, India

Comparative study of the radon and thoron concentrations in the indoor environment of the Budhakedar region of the Garhwal Himalaya, India

Simultaneous measurements of radon, thoron and thoron progeny and induced cancer risk assessment in Djeno, Pointe-Noire, Republic of Congo.

In this study, the activity concentrations of radon (222Rn), thoron (220Rn) and thoron progeny were measured simultaneously in Djeno (Pointe-Noire, Republic of Congo) using RADUET detectors to evaluate the air quality and the radiological risks due to the inhalation of these radionuclides. Activity concentrations of radon progeny were calculated from those of radon. Indoor radon, thoron and progenies followed a lognormal distribution ranging between 20 and 40, 6 and 62, 8 and 17.6 and 0.4 and 19.6Bqm-3 for radon, thoron, radon progeny and thoron progeny, respectively. Mean values for radon were lower than the worldwide values estimated by the United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are 40Bqm-3 (arithmetic mean) and 45Bqm-3 (geometric mean). Radon concentrations in the dwellings under study were below the World Health Organization and the International Commission on Radiological Protection recommended reference levels, which are, respectively, 100 and 300Bqm-3. The mean concentration of thoron was twice the world average value of 10Bqm-3 estimated by UNSCEAR. Thoron progeny mean concentration was sharply greater than the typical value (0.3Bqm-3) for indoor atmosphere provided by UNSCEAR. Annual effective dose ranges were 0.40-0.87mSv (arithmetic mean, 0.57±0.11mSv) for radon and 0.10-4.14mSv (arithmetic mean, 0.55±0.77mSv) for thoron. The mean value for radon was lower than the value (1.15mSv) estimated by UNSCEAR, while the mean value for thoron was five times higher than the UNSCEAR value (0.10mSv). The study showed that the use of the typical equilibrium factor value given by UNSCEAR to compute effective dose led to an error above 80%. Finally, the results of this study showed that the excess relative risk of radon-induced cancer was low, below 2% for the population under 55y. The results presented in the present study prove that the population of Djeno is exposed to a relatively low potential risk of radon- and thoron-induced cancer.

Assessment of radiological risk associated with thoron gas at primary schools in Al-Najaf city, Iraq

Children spend considerable time at home and school, so school is likely to be a second source of natural radionuclide exposure after home. This study evaluates the radiological risk associated with thoron gas in the air within the building of one hundred primary schools in Al-Najaf City, Iraq, using a CR-39 detector. The results of the average value of thoron concentration detector, the annual effective dose (AED), Excessive Lifetime Cancer Risk (ELCR) × 10−3, and Lung Cancer Case (LCC) × 10−9 measured in the building of the schools were 7.47 ± 2.85 Bq/m3, 0.03 ± 0.01 mSv/y, 0.11 ± 0.04, and 0.54 ± 0.20, respectively. All the results of indoor thoron were below the global average limit. The results of the radiological survey due to thoron concentrations for studied primary schools suggest that the radionuclides and their radiological hazard indexes in all studied schools in AL Najaf city, Iraq, do not impose a health hazard.

Assessment of Radiological Risks due to Indoor Radon, Thoron and Progeny, and Soil Gas Radon in Thorium-Bearing Areas of the Centre and South Regions of Cameroon

Indoor radon, thoron and thoron progeny concentrations, along with the equilibrium factor for thoron progeny and soil gas radon concentrations, have been measured to assess radiological risks in the centre and south regions of Cameroon. Indoor radon and thoron concentrations were estimated using radon–thoron discriminative detectors (RADUET), while thoron progeny monitors measured the equilibrium equivalent thoron concentration (EETC). Radon concentrations in the soil were determined using a MARKUS 10 detector. It was found that radon, thoron and thoron progeny concentrations range between 19 and 62 Bq m−3, 10 and 394 Bq m−3 and 0.05 and 21.8 Bq m−3, with geometric means of 32 Bq m−3, 98 Bq m−3 and 4.9 Bq m−3, respectively. The thoron equilibrium factor ranges between 0.007 and 0.24, with an arithmetic mean of 0.06 ± 0.03; this is higher than the world average value of 0.02 provided by the United Nations Scientific Commission on the Effects of Atomic Radiation(UNSCEAR, New York, USA). The level of the soil radon concentration ranges from 4.8 to 57.3 kBq m−3, with a geometric mean of 12.1 kBq m−3 at a depth of 0.7 m. Of the sampling points, 66% fall within normal radon risk areas, and 3% of the sampling areas are high radon risk areas exceeding 50 kBq m−3. The annual effective dose was found to be 0.03 ± 0.01 mSv for radon, 0.08 ± 0.05 mSv for thoron, 0.63 ± 0.12 mSv for radon progeny and 1.40 ± 0.84 mSv for thoron progeny. The total dose is estimated to be 2.14 mSv y−1. The mean estimated indoor excess lifetime cancer risk values due to radon, thoron, radon progeny and thoron progeny are 0.12 × 10−3, 0.31 × 10−3, 2.51 × 10−3 and 5.58 × 10−3, respectively. Thoron progeny contributed 60% to the effective dose. Thus, thoron progeny cannot be neglected in dose assessments, in order to avoid biased results in radio-epidemiological studies.

Radon and Thoron Concentrations in the Air of Three Schools in East Baghdad

Radon and Thoron Concentrations in the Air of Three Schools in East Baghdad

Estimation of radiation dose due to thoron and progeny inhalation in high background natural radiation area of Odisha, India

Abstract Results of the preliminary measurements of indoor radon, thoron and progeny concentrations showed very high values of thoron concentrations in the eastern coastal region of Odisha, India. Therefore, measurements of thoron and its progeny concentrations were extended to a larger number of houses in this area for the assessment of the radiation dose received by the public. The measured values of thoron concentrations were used for the calculation of annual effective doses. The estimated values of the annual effective dose due to thoron exposure were observed in the range of 0.2–14.7 mSv. The estimated radiation doses responsible for thoron exposure were observed considerably high in the region. The results obtained are compared with those obtained in other studies performed so far in the study area and a review of different studies involving different measurement techniques is presented in the paper. The results of this study support the preliminary studies showing high values of thoron levels in the study area.

A study of radon, thoron and annual effective dose in some Egyptian dwellings by twin-cup dosimeter technique with LR-115 detectors

In the present study, Solid State Nuclear Track Detectors (LR-115–type II) based twin-cup dosimeters were used for estimating radon (222Rn) and thoron (220Rn) gas concentration levels in the environmental air of thirty dwellings in ten cities in Egypt. In the studied dwellings radon concentration levels were found to vary from 24.80 ± 3.98 to 39.71 ± 8.71 Bq m−3 with an average of 32.64 ± 4.34 Bq m−3 whereas thoron concentration is found to vary from 10.46 ± 2.87 to 15.41 ± 2.72 Bq m−3 with an average of 12.48 ± 1.58 Bq m−3. The total annual effective dose by the inhabitants of these dwellings due to radon and thoron was found below the recommended limit by the international agencies. The present study concluded that the dwellings are safe without posing significant radiological threats to human beings.

Метод измерения среднегодовой ЭРОА торона в современных жилых зданиях

The article is devoted to a new method for determining the average annual value of the equivalent equilibrium concentration (EEC) of thoron in residential buildings. The developed method closes the issue of the lack of instrumental support in the Russian Federation for measuring the average annual and average seasonal value of the thoron EEC in residential premises and workplaces. Using this method, measurements were carried out and the average annual values of EEC for the city of Ekaterinburg were estimated.

Evaluation of indoor 222Rn and 220Rn concentrations in Dakshina Kannada, Karnataka, India

Naturally occurring radioactive gases which tend to build up (radon and thoron) in indoor environs can cause deleterious health effects including the development of lung cancer. The present study aims to measure 222Rn and 220Rn levels in dwellings in different seasons in the environs of Dakshina Kannada region of India. The 222Rn and 220Rn concentrations were measured in the monsoon, autumn, winter, and summer seasons using Solid State Nuclear Track Detector (SSNTD, LR-115 type II) films fixed in single-entry pinhole cylindrical twin-cup dosimeters. The higher 222Rn levels in indoors were observed during winter with an average concentration of 38.8Bqm-3 and lower during summer with an average of 14.1Bqm-3. The average indoor thoron concentration was also highest in winter with an average value of 25.5Bqm-3 and lowest in summer with 8.8Bqm-3. The annual inhalation dose ranged from 0.44 to 1.06mSvyear-1 with a mean value of 0.66mSvyear-1. The annual effective dose varied from 1.03 to 2.57mSvyear-1 with an average value of 1.59mSvyear-1. The assessed values have been contrasted with the limit suggested by the UNSCEAR and the ICRP and were found to be within the permissible level. The normality of frequency distribution curves of 222Rn and 220Rn concentrations was assessed by the Kolmogorov-Smirnov test.

Developing a radon monitor for simultaneous measurement of Rn-222 and Rn-220 with less influence of humidity based on electrostatic collection and CR-39 detector

Based on electrostatic collection and CR-39, a novel radon monitor (Hynu EIRM-II) was designed to reduce the effect of humidity for simultaneous measurement of Rn-222 and Rn-220 with two 50 mL hemispherical internal cells connected in a serial configuration. A 10 cm tube connects two internal cells to avoid entry of Rn-220 into the second one. While the relative humidity in the internal cell of Hynu EIRM-II is 1% or above 10%, the difference of Po-216 collection efficiency estimated by an improved model is 8.36% at a cell-wall voltage of 2000 V. The simultaneous measurement experiments of Rn-222 and Rn-220 concentrations were performed under three relative humidity ranges of 5%–10%, 80%–88% and 99%–100%. These experimental data show that the maximum differences of the calibration factors for Rn-222 and Rn-220 are 10.13% and 14.42%, respectively. The detection efficiency of Hynu EIRM-II was less affected by humidity. The measurement data of Rn-222 and Rn-220 by the Hynu EIRM-II can provide references for further improvement of radon monitors to accurately measure radon and thoron concentration.