Radiation doses to individuals due to 238U, 232Th and 222Rn from the immersion in thermal waters and to radon progeny from the inhalation of air inside thermal stations

In Morocco, thermal waters have been used for decades for the treatment of various diseases. To explore the exposure pathway of ²³⁸U, ²³²Th and ²²²Rn to the skin of bathers from the immersion in thermal waters, these radionuclides were measured inside waters collected from different Moroccan thermal springs, by means of CR-39 and LR-115 type II solid-state nuclear track detectors (SSNTDs), and corresponding annual committed effective doses to skin were determined. Accordingly, to assess radiation dose due to radon short-lived decay products from the inhalation of air by individuals, concentrations of these radionuclides were measured in indoor air of two thermal stations by evaluating mean critical angles of etching of the CR-39 and LR-115 II SSNTDs. Committed effective doses due to the short-lived radon decay products ²¹⁸Po and ²¹⁴Po by bathers and working personnel inside the thermal stations studied were determined.     

Study of radon/thoron exhalation rate,soil-gas radon concentration,and assessment of indoor radon/thoron concentration in Siwalik Himalayas of Jammu & Kashmir

In the present study, the soil-gas radon concentration was assessed at different depth intervals, i.e., 15 cm, 30 cm, 60 cm, and 100 cm from the 30 villages of Jammu &; Kashmir, India using RAD7, an electrostatic solid state alpha detector. The radon mass exhalation and thoron surface exhalation rate has also been measured in the selected 18 soil samples out of 30 of different grain sizes (i.e., 1 mm, 300 µm, 150 µm). The active radon and thoron concentrations were also assessed in the 20 villages. Both the exhalation rates and active radon/thoron concentration were measured using SMART Rn Duo, a portable radon monitor. The average values of soil-gas radon concentration were 210 ± 84 Bq m^?3, 1261 ± 963 Bq m^?3, 4210 ± 1994 Bq m^?3, and 671 ± 305 Bq m^?3 at the depth intervals of 15 cm, 30 cm, 60 cm, and 100 cm, respectively. The exhalation rate of radon and thoron from soil was found to decrease with the increase of grain size, as smaller soil particles make relatively more contribution to radon and thoron exhalations from the ground surface than larger soil particles. The measured Pearson's correlation coefficient was obtained as statistically significant between different quantities under two-tailed test.     

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.     

Estimation of dose rate for indoor radon from building materials

The internal dose rate due to indoor radon (Rn) emissions from building materials is estimated. It is observed that the contribution from building materials to the dose rate is very small. The average indoor radon concentration in 75 different rooms is found to be 55 ± 12 Bq. m^–3. Assuming an occupancy factor of 0.8, the annual average effective dose equivalent is 1.7 mSv. It seems that soil gas is mainly responsible for the internal exposure from indoor Rn.     

Spatial distribution of 222Rn concentrations and dose estimations in various waters

In this article, the levels of ²²²Rn concentrations, annual effective doses, and excess lifetime cancer risk estimations were investigated for water samples in the city of Osmaniye, located in the southern part of Turkey. The measurements were conducted using a radon gas analyzer (AlphaGUARD PQ 2000 PRO). The arithmetic average of ²²²Rn concentrations was 0.44 Bq.L^?1 with a geometric standard deviation of 0.19 and geometric average 0.41 Bq.L^?1. The results obtained were compared with the findings of other studies. All measured radon concentrations were below the values recommended by the World Health Organization and the U.S. Environmental Protection Agency. The associated radiological parameters such as annual effective doses (AED) and excess lifetime cancer risk (ELCR) from consumption of these waters were calculated. The computed average annual effective doses for ingestion and inhalation as well as excess lifetime cancer risk were estimated to be 1.13 μSv.y^?1, 1.10 μSv.y^?1, and 3.95 × 10^?6, respectively. ²²²Rn concentration, AED, and ELCR interpolated values of the region were determined and mapped using the Kriging method. The results of radon concentrations in this study provide a data baseline for future studies on subsequent evaluations of possible future environmental contamination of Osmaniye Province.     

Measurement of <Superscript>131</Superscript>I activity in thyroid of nuclear medical staff and internal dose assessment in a Polish nuclear medical hospital

This paper presents results of ¹³¹I thyroid activity measurements in 30 members of the nuclear medicine personnel of the Department of Endocrinology and Nuclear Medicine Holy Cross Cancer Centre in Kielce, Poland. A whole-body spectrometer equipped with two semiconductor gamma radiation detectors served as the basic research instrument. In ten out of 30 examined staff members, the determined ¹³¹I activity was found to be above the detection limit (DL = 5 Bq of ¹³¹I in the thyroid). The measured activities ranged from (5 ± 2) Bq to (217 ± 56) Bq. The highest activities in thyroids were detected for technical and cleaning personnel, whereas the lowest values were recorded for medical doctors. Having measured the activities, an attempt has been made to estimate the corresponding annual effective doses, which were found to range from 0.02 to 0.8 mSv. The highest annual equivalent doses have been found for thyroid, ranging from 0.4 to 15.4 mSv, detected for a cleaner and a technician, respectively. The maximum estimated effective dose corresponds to 32% of the annual background dose in Poland, and to circa 4% of the annual limit for the effective dose due to occupational exposure of 20 mSv per year, which is in compliance with the value recommended by the International Commission on Radiological Protection.     

Thoron levels in traditional Chinese residential dwellings

A survey on radon (²²²Rn), thoron (²²⁰Rn) and its decay products (²²⁰RnD) was conducted in Chinese traditional residential dwellings constructed with loam bricks or soil wall. The activity concentrations in 164 dwellings under investigation were 72.4±59.2 (arithmetic mean, AM) and 57.5±2.0 Bq m⁻³ (geometric mean, GM) for ²²²Rn, and 318±368 and 162±3.7 Bq m⁻³ for ²²⁰Rn, respectively. For ²²⁰RnD, 67 dwellings were studied. The AM of the ²²⁰RnD equilibrium equivalent concentration was 3.8±3.3 Bq m⁻³ with a maximum value of 15.8 Bq m⁻³. On the basis of these results, the average annual effective doses to the local residents due to radon and thoron exposure were 1.44–4.62 mSv. Thoron contributes 12.9–56.6% to the total doses. Preliminary results show that there is a relation between ²²⁰RnD in air and ²³²Th in soil. The correlation factors of outdoor and indoor were 0.88 and 0.40. The ²³²Th activity content of Chinese soil is estimated to be about two times the world average. The traditional residential dwellings with soil construction are still common in China. Further investigations on the ²²⁰Rn level in these dwelling with the aim of dose reduction are proposed.     

Levels of formaldehyde in residential indoor air of Gonabad,Iran

Abstract

Human health has been identified to be affected more significantly by indoor air quality. Among numerous pollutants present in indoor air, formaldehyde (FA) is of great concern because of its highly hazardous nature. The concentrations of FA were determined from 20 newly decorated homes in the city of Gonabad, Iran during 2015. It was found that the indoor air levels of FA in all the sampled houses were exceptionally high in the range of 21 to 360 µg/m³ (mean of 149.3 µg/m³). If the 24-h average concentrations of FA measured from those sites were concerned, nearly 40% of them were seen to exceed the WHO guideline values (i.e., 100 µg/m³). One of the important reasons for the high concentrations could be low air exchange rates in those houses (e.g., from 0.18 to 0.37?h^?1), high levels of humidity in the newly decorating houses and stronger sources in the indoor environment. Furthermore, its pollution in homes with natural ventilation was seen to be much higher than those of mechanical ventilation. Due to high levels of indoor FA, more effective control procedures should be developed and employed to reduce the risk associated with formaldehyde exposure.     

Occurrence of radon in some schools of Parma and Reggio Emilia (Northern Italy)

Summary Forty-seven measurement of radon concentration were made in some schools of Parma, Reggio Emilia, Albinea and Borzano. The method used was that of activated carbon canisters, which were placed in classrooms, laboratories, libraries and headmaster's offices for at least 48 hours in the period November '90–March '91. It was possible to determine the amount of radon in each canister counting the Pb-214 and Bi-214 gamma emitters by means of NaI (Tl) and Ge (I) detectors. The mean radon concentrations were: 20 Bq/m³ in Parma; 24 Bq/m³ in Reggio Emilia; 46 Bq/m³ in Borzano and 52 Bq/m³ in Albinea. The values recorded in schools are similar to the values previously recorded in dwellings of Parma and Reggio Emilia.     

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.     

Measurements of radon activity concentration in mouse tissues and organs

The purpose of this study is to investigate the biokinetics of inhaled radon, radon activity concentrations in mouse tissues and organs were determined after mice had been exposed to about 1 MBq/m³ of radon in air. Radon activity concentrations in mouse blood and in other tissues and organs were measured with a liquid scintillation counter and with a well-type HP Ge detector, respectively. Radon activity concentration in mouse blood was 0.410?±?0.016 Bq/g when saturated with 1 MBq/m³ of radon activity concentration in air. In addition, average partition coefficients obtained were 0.74?±?0.19 for liver, 0.46?±?0.13 for muscle, 9.09?±?0.49 for adipose tissue, and 0.22?±?0.04 for other organs. With these results, a value of 0.414 for the blood-to-air partition coefficient was calculated by means of our physiologically based pharmacokinetic model. The time variation of radon activity concentration in mouse blood during exposure to radon was also calculated. All results are compared in detail with those found in the literature.     

Radionuclides content in grape molasses soil samples from Central Black Sea region of Turkey

The activity concentrations of radionuclides in grape molasses soil samples collected from Zile (Tokat) plain in the Central Black Sea region of Turkey were measured by using gamma spectrometer with a NaI(Tl) detector. Also, the concentrations of ²²²Rn in soil samples and air were estimated essentially taking the activity concentrations of ²²⁶Ra measured in soil samples. Grape molasses soil samples with calcium carbonate content are used for sedimentation for making molasses in this region. The average activity concentrations of ²³²Th, ²²⁶Ra, ⁴⁰K, and ¹³⁷Cs were found as 62 ± 2, 68 ± 3, 479 ± 35, and 8.0 ± 0.3 Bq kg^?1, respectively. The average concentrations of ²²²Rn in soil samples and air were estimated to be 50 kBq m^?3 and 144 Bq m^?3. From the activity concentrations, absorbed gamma dose rate in outdoor air (D), annual effective dose from external exposure (E_E), annual effective dose from inhalation of radon (E_I), and excess lifetime cancer risk (ELCR) were estimated in order to assess radiological risks. The average values of D, E_E, E_I, and ELCR were found to be 90 nGy h^?1, 110 μSv y^?1, 1360 μSv y^?1, and 4 × 10^?4, respectively.     

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.     

Distribution of 222Rn in groundwater and estimation of resulting radiation dose to different age groups: A case study from Bangalore City

Ingesting waters holding high levels of natural occurring radioactive element like Radon would contribute to increase in the effective dose received by people followed by an increased prevalence of cancer. The current study is an attempt to describe the extent of contribution of ²²²Rn to natural background radiation and the resultant effective dose to public of different age groups. In order to do so, 65 groundwater samples from selected parts of Bangalore city were collected and analyzed for radon activity using RAD7 radon monitor coupled with RAD H₂O accessories. The radon activity was in the range of 3.05–696 Bq/L (mean: 91.39 Bq/L) and 92.31% of the groundwater samples recorded elevated radon concentration above the United States environmental protection agency (USEPA's) Maximum Contaminant Level (MCL) value of 300 pCi/L, corresponding to 11.1 Bq/L. The mean annual effective dose contribution of people falling under different age groups (viz., infants, children, teens: males and females, adults: males and females, pregnant and lactating women) due to ingestion of water-borne ²²²Rn ranged from 0.082 to 0.444 mSv/y and was found to be higher in all the age groups of males compared to respective female age groups, but well within the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and World Health Organization (WHO) proposed limit of 1 mSv/y.     

Childhood cancer and residential radon exposure – results of a population-based case-control study in Lower Saxony (Germany)

A population-based case-control study on risk factors for childhood malignancies was used to investigate a previously reported association between elevated indoor radon concentrations and childhood cancer, with special regard to leukaemia. The patients were all children suffering from leukaemia and common solid tumours (nephroblastoma, neuroblastoma, rhabdomyosarcoma, central nervous system (CNS) tumours) diagnosed between July 1988 and June 1993 in Lower Saxony (Germany) and aged less than 15 years. Two population-based control groups were matched by age and gender to the leukaemia patients. Long-term (1 year) radon measurements were performed in those homes where the children had been living for at least 1 year, with particular attention being paid to those rooms where they had stayed most of the time. Due to the sequential study design, radon measurements in these rooms could only be done for 36% (82 leukaemias, 82 solid tumours and 209 controls) of the 1038 families initially contacted. Overall mean indoor radon concentrations (27 Bq m^–3) were low compared with the measured levels in other studies. Using a prespecified cutpoint of 70 Bq m^–3, no association with indoor radon concentrations was seen for the leukaemias (odds ratio (OR): 1.30; 95% confidence interval (95% CI): 0.32–5.33); however, the risk estimates were elevated for the solid tumours (OR: 2.61; 95% CI: 0.96–7.13), mainly based on 6 CNS tumours. We did not find any evidence for an association between indoor radon and childhood leukaemia, which is in line with a recently published American case-control study. There is little support for an association with CNS tumours in the literature. Received: 14 December 1998 / Accepted in revised form: 10 June 1999     

Radon survey in dwellings of Gansu,China: the influence of thoron and an attempt for correction

Alpha track detectors used in a previous investigation of the US National Cancer Institute and the China Ministry of Health on indoor radon ((222)Rn) in Gansu, China, proved to be influenced by (220)Rn (thoron), thus overestimating the (222)Rn level. Therefore, the detector was improved used in the previous survey. The new detectors allow discrimination between the two isotopes without any disturbance of the (222)Rn measurement. With this detector, a semi-annual study was conducted in 49 traditional dwellings of a village in Gansu. The arithmetic (AM) and geometric (GM) mean (222)Rn concentrations were 120 +/- 61 and 105 Bq m(-3) (with geometric standard deviation GSD = 1.8), respectively, while the mean (220)Rn concentrations at 2.5 cm wall distance were 430 +/- 210 Bq m(-3) (AM) and 350 Bq m(-3) (GM) with GSD = 2.3. The high thoron concentrations demonstrate the importance of the (220)Rn contribution to radiation exposure, in the investigated area. The actual level of indoor (222)Rn was about three times lower than that in the previous investigation which was affected by (220)Rn. A correction method for the radon results of the previous study is proposed, which provides (222)Rn and (220)Rn values comparable with those obtained in the study presented here.     

Comparison of various methods of estimating radon dose at underground workplaces in wineries

Levels of radon were surveyed in the air at underground workplaces of eight major Slovenian wineries. Geometric mean and geometric standard deviation values, respectively, obtained with different devices were 81 Bq m⁻³ and 2.3 with alpha scintillation cells, 114 Bq m⁻³ and 2.0 by exposing etched track detectors for 1–5 months, and 183 Bq m⁻³ and 2.6 from 1–4-weeks continuous measurements. The equilibrium factor was 0.25–0.67, and the unattached fraction of radon short-lived decay products was in the range 0.09–0.20. Effective doses were calculated and compared based on radon data obtained with different techniques.     

Temporal variation of thoron decay product concentration in the atmosphere and comparison with radon decay product concentration

Seasonal and long-term variation of the airborne ²¹²Pb concentration, representative of the equilibrium equivalent concentration of thoron decay products (EEC_Rn220), was investigated from 1989 through 1996 at a semi-natural location in southern Germany. Continuous measurement yielded a long-term average concentration of 0.082 Bq m^–3, while daily mean concentrations varied from ≤0.01 to 0.34 Bq m^–3. An average annual effective dose of 1.4 mSv due to outdoor thoron progeny concen-tration was estimated. This is about 2% of the dose due to the average short-lived radon progeny concentration (EEC_Rn222) of 8.4 Bq m^–3 measured for this location in the same period. In most years the seasonal pattern of ²¹²Pb activity concentration in the atmosphere is characterized by two maxima: the first in May and the second one in September. Low concentrations are observed from November through February of each year. This is in contrast to the behaviour of the short-lived ²²²Rn progeny which exhibit enhanced concentrations exactly during these months. The most probable reason for the different temporal behaviour of ²¹²Pb is the extremely reduced flux of thoron gas from the ground during the winter months. Received: 19 August 1997 / Accepted in revised form: 22 January 1998     

Age-dependent inhalation doses to members of the public from indoor short-lived radon progeny

The main contribution of radiation dose to the human lungs from natural exposure originates from short-lived radon progeny. In the present work, the inhalation doses from indoor short-lived radon progeny, i.e., ²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi, and ²¹⁴Po, to different age groups of members of the public were calculated. In the calculations, the age-dependent systemic biokinetic models of polonium, bismuth, and lead published by the International Commission on Radiological Protection (ICRP) were adopted. In addition, the ICRP human respiratory tract and gastrointestinal tract models were applied to determine the deposition fractions in different regions of the lungs during inhalation and exhalation, and the absorption fractions of radon progeny in the alimentary tract. Based on the calculated contribution of each progeny to equivalent dose and effective dose, the dose conversion factor was estimated, taking into account the unattached fraction of aerosols, attached aerosols in the nucleation, accumulation and coarse modes, and the potential alpha energy concentration fraction in indoor air. It turned out that for each progeny, the equivalent doses to extrathoracic airways and the lungs are greater than those to other organs. The contribution of ²¹⁴Po to effective dose is much smaller compared to that of the other short-lived radon progeny and can thus be neglected in the dose assessment. In fact, 90 % of the effective dose from short-lived radon progeny arises from ²¹⁴Pb and ²¹⁴Bi, while the rest is from ²¹⁸Po. The dose conversion factors obtained in the present study are 17 and 18 mSv per working level month (WLM) for adult female and male, respectively. This compares to values ranging from 6 to 20 mSv WLM^?1 calculated by other investigators. The dose coefficients of each radon progeny calculated in the present study can be used to estimate the radiation doses for the population, especially for small children and women, in specific regions of the world exposed to radon progeny by measuring their concentrations, aerosol sizes, and unattached fractions.     

Comparison of antioxidative effects between radon and thoron inhalation in mouse organs

Radon therapy has been traditionally performed globally for oxidative stress-related diseases. Many researchers have studied the beneficial effects of radon exposure in living organisms. However, the effects of thoron, a radioisotope of radon, have not been fully examined. In this study, we aimed to compare the biological effects of radon and thoron inhalation on mouse organs with a focus on oxidative stress. Male BALB/c mice were randomly divided into 15 groups: sham inhalation, radon inhalation at a dose of 500 Bq/m³ or 2000 Bq/m³, and thoron inhalation at a dose of 500 Bq/m³ or 2000 Bq/m³ were carried out. Immediately after inhalation, mouse tissues were excised for biochemical assays. The results showed a significant increase in superoxide dismutase and total glutathione, and a significant decrease in lipid peroxide following thoron inhalation under several conditions. Additionally, similar effects were observed for different doses and inhalation times between radon and thoron. Our results suggest that thoron inhalation also exerts antioxidative effects against oxidative stress in organs. However, the inhalation conditions should be carefully analyzed because of the differences in physical characteristics between radon and thoron.