Search Results (9)

This paper reports the levels of radon (Rn), thoron (Tn), and their progeny (TnP) concentrations in dwellings; studies factors influencing these concentrations; and assesses the associated lung cancer risk in Akonolinga’s area in Cameroon, where rutile deposits have been identified but are not yet industrially exploited. Indoor Rn and Tn were determined using CR39-based detectors. Additionally, Rn in soil gas, ²²⁶Ra, and ²³²Th concentrations in soil were measured using Markus 10, high purity germanium detector (HPGe), respectively. On average, indoor Rn, Tn concentration, and the equilibrium equivalent Thoron concentration (EETC) or TnP were 39.5, 68.1, and 5.0 Bq m⁻³, respectively. Average concentrations of Rn in soil gas, ²²⁶Ra, and ²³²Th in soil were 24.3 kBq m⁻³, 17 Bq kg⁻¹, and 27 Bq kg⁻¹, respectively. Correlation analysis indicates that indoor radon and thoron levels were tightly linked with factors such as their precursor concentrations in soil, the building materials, dwelling architecture, and inhabitant living habits. Furthermore, it was observed that Rn and TnP were the major contributors to the inhalation effective dose, accounting for 39.6% and 56.7% of the total, respectively. The estimated excess lifetime cancer risk (ELCR) from the exposition to Rn and TnP was found to be 2.93 × 10⁻³ and 4.36 × 10⁻³, respectively, exceeding the global average, raising health concerns. Full article

The diamondback moth (DBM), Plutella xylostella, is the main pest of Brassicas crops worldwide, and its recorded resistance to 101 active ingredients indicates it is difficult to control. The purpose of this study was to investigate the hypothesis that P. xylostella has fitness costs associated with its resistance to lufenuron, a chitin-synthesis inhibitor insecticide. Thus, concentration–mortality bioassays were performed for susceptible (REC-S), resistant (BZR-R) populations, their progenies F1 and F1′, and one established population without selection pressure (BZR-Rns) after four generations. A fertility life table was used to assess the biological performance of the REC-S and BZR-R. BZR-Rns of P. xylostella. The larval stage, longevity, and survival differed between populations. The reproductive rate (R₀) was significantly lower in the F1 (♀R × ♂S) (28.19) and F1′ (♀S × ♂R) (34.06) progenies compared with their parents, but not with the relaxed BZR-Rns (39.39). The mean generation time (T), intrinsic rate of population growth (r_m), and doubling time (DT) differed between REC-S and progenies, with fitness of 0.52 and 0.64 for F1 and F1′, respectively. Overall, the results suggest that the resistance of P. xylostella to lufenuron is stable and that low fitness costs appear to be associated with resistance to lufenuron, although heterozygotes showed lower fitness than their parents. Strategies such as preserving refuge areas, rotation of modes of action, etc., are essential for resistance management and prolonging the efficacy of control agents; this highlights the importance of integrated insecticide resistance management. Full article

Small non-coding RNAs, such as microRNAs (miRNA) and tRNA-derived fragments (tRF), are known to be involved in post-transcriptional gene regulation. Research has provided evidence that small RNAs may influence immune development in calves. Bovine leukosis is a disease in cattle caused by Bovine Leukemia Virus (BLV) that leads to increased susceptibility to opportunistic pathogens. No research has addressed the potential influence that a maternal BLV infection may have on gene regulation through the differential expression of miRNAs or tRFs in progeny. Blood samples from 14-day old Holstein calves born to BLV-infected dams were collected. Antibodies for BLV were assessed using ELISA and levels of BLV provirus were assessed using qPCR. Total RNA was extracted from whole blood samples for small RNA sequencing. Five miRNAs (bta-miR-1, bta-miR-206, bta-miR-133a, bta-miR-133b, and bta-miR-2450d) and five tRFs (tRF-36-8JZ8RN58X2NF79E, tRF-20-0PF05B2I, tRF-27-W4R951KHZKK, tRF-22-S3M8309NF, and tRF-26-M87SFR2W9J0) were dysregulated in calves born to BLV-infected dams. The miRNAs appear to be involved in the gene regulation of immunological responses and muscle development. The tRF subtypes and parental tRNA profiles in calves born to infected dams appear to be consistent with previous publications in adult cattle with BLV infection. These findings offer insight into how maternal BLV infection status may impact the development of offspring. Full article

The change of natural ionizing radiation and the radon exhalation rates from typical building materials in underground parking lots are presented in the article. The activity concentration of natural radionuclides ²³²Th, ²²⁶Ra, and ⁴⁰K in six important types of construction materials, which are mostly used in Lithuania, were analyzed using high-resolution gamma spectroscopy. The highest values were found in concrete and ferroconcrete samples: ²²⁶Ra 44 and 90 Bq kg⁻¹; ²³²Th 29 and 34 Bq kg⁻¹; ⁴⁰K 581 and 603 Bq kg⁻¹. A strong positive correlation (0.88) was observed between radium activity concentration and radon concentration. The activity indexes (I_α and I_γ) and radium equivalent activity (R_eq) evaluating the suitability of materials for such constructions from the view of radiation safety were determined. The average values of the calculated absorbed dose rate in samples ranged from 18.24 nGy h⁻¹ in the sand to 87.26 nGy h⁻¹ in ferroconcrete. The calculated annual effective dose was below the limit of 1.0 mSv y⁻¹. The values of the external and internal hazards index (H_ex and H_in) were all below unity, and the values of I_γ and I_α were below the recommended levels of 0.5 and 1. Dosimetric analysis of underground parking lots was carried out. It was determined that the external equivalent dose rate caused by the ²²²Rn progeny radiation in the underground car parking lots varies from 17 to 30% of the total equivalent dose rate. Full article

A natural radioactivity in thermal water was investigated based on 19 selected thermal waters from Poland. The analysed results show that the radionuclides’ concentrations in the study waters vary over a wide range. The temperature of the waters varies from above 20 °C to above 80 °C. The waters are characterised by different mineralisation, chemical compositions, and belong to different hydrochemical types. There is a good correlation between the water temperature and the depths of the aquifer formations occurrence, suggesting the thermal energy originates from the thermal geogradient. The concentration of radium is well correlated with the water mineralisation. The ratio of radium activity (²²⁶Ra/²²⁸Ra) in groundwater relates not only the ratio of uranium activity to that of thorium (²³⁸U/²³²Th) in aquifer formation, but also depends on the physical and chemical water properties. Based on the concentration of radon and its transport model, the radiation exposures due to inhalation of ²²²Rn and its progeny for employees and clients of the spa were assessed. The use of the thermal waters as a drinking resource may be problematic due to the possibility of exceeding the recommended annual committed effective dose 0.1 mSv. Full article

The present paper outlines characteristics of thoron and its progeny in the indoor environment. Since the half-life of thoron (²²⁰Rn) is very short (55.6 s), its behavior is quite different from the isotope radon (²²²Rn, half-life 3.8 days) in the environment. Analyses of radon and lung cancer risk have revealed a clearly positive relationship in epidemiological studies among miners and residents. However, there is no epidemiological evidence for thoron exposure causing lung cancer risk. In contrast to this, a dosimetric approach has been approved in the International Commission on Radiological Protection (ICRP) Publication 137, from which new dose conversion factors for radon and thoron progenies can be obtained. They are given as 16.8 and 107 nSv (Bq m⁻³ h)⁻¹, respectively. It implies that even a small quantity of thoron progeny will induce higher radiation exposure compared to radon. Thus, an interest in thoron exposure is increasing among the relevant scientific communities. As measurement technologies for thoron and its progeny have been developed, they are now readily available. This paper reviews measurement technologies, activity levels, dosimetry and resulting doses. Although thoron has been underestimated in the past, recent findings have revealed that reassessment of risks due to radon exposure may need to take the presence of thoron and its progeny into account. Full article

An improved passive CR-39-based direct ²²²Rn/²²⁰Rn progeny detector with 3 detection channels was designed and tested in this study to measure and calculate equilibrium equivalent concentration (EEC) of both ²²²Rn and ²²⁰Rn without the equilibrium factor. A theoretical model was established to calculate the EEC with optimization. Subsequently, an exposure experiment was carried out to test the performance of this detector, and we compared the chamber experiment and the theoretical model by estimating and measuring various parameters. The deposition flux of progeny derived from the prediction agreed well with the value measured in the exposure chamber. The energy-weighted net track density (NTD) measured by this detector is much more reliable to reflect the linear relation between NTD and time-integrated EEC. Since the detector is sensitive to the exposure environmental condition, it is recommended to apply the detector to measure the EEC after its calibration in a typical indoor environment. Full article

The International Commission on Radiological Protection (ICRP) recently recommended a new dose conversion factor for radon based on the latest epidemiological studies and dosimetric model. It is important to evaluate an inhalation dose from radon and its progeny. In the present study, a passive radon personal monitor was designed using a small container for storing contact lenses and its performance was evaluated. The conversion factor for radon (²²²Rn), the effect of thoron (²²⁰Rn) concentration and the air exchange rate were evaluated using the calibration chamber at Hirosaki University. The minimum and maximum detectable radon concentrations were calculated. The conversion factor was evaluated as 2.0 ± 0.3 tracks cm⁻² per kBq h m⁻³; statistical analyses of results showed no significant effect from thoron concentration. The minimum and maximum detectable radon concentrations were 92 Bq m⁻³ and 231 kBq m⁻³ for a measurement period of three months, respectively. The air exchange rate was estimated to be 0.26 ± 0.16 h⁻¹, whose effect on the measured time-integrated radon concentration was small. These results indicate that the monitor could be used as a wearable monitor for radon measurements, especially in places where radon concentrations may be relatively high, such as mines and caves. Full article

Groundwater contains naturally occurring radioactive materials (NORMs) through water–rock interactions. Although a recent study found that the NORMs are accumulated into the filters utilized in bottled mineral-water facilities, the accumulation mechanism and effects have rarely been studied. This study is, therefore, conducted to determine the mechanism of NORM accumulation in filters during water treatment processes and to provide a first estimate of the level of radiological risk for workers in five bottled-mineral-water facilities. The level of Rn-222 decreased dramatically at the first filters (FF) encountered after passing through water storage tanks, while surface radiation sharply increased. The increase of radioactivity on the FF was mainly caused by the accumulation of short-lived radon progenies through decay processes inside the water tanks. Although the estimated radiological risk was lower under certain circumstances compared to the public dose limit of 1 mSv yr⁻¹, the radiological risk should be properly managed in case of direct and/or close handling of the used filters during filter replacement procedures. Full article