Non-uranium Mines Research Articles

Alteration of genome-wide DNA methylation in non-uranium miners induced by high level radon exposure.

In China, according to statistics about underground non-uranium mine radon levels, 15% exceed the national standard intervention level of 1000Bq/m3, and some mines may exceed 10,000Bq/m3. The relationship between radon exposure in underground miners and lung cancer has already been established, but the mechanisms and biological processes underlying it are poorly understood. In order to identify the genome-wide DNA methylation profile associated with long-term radon exposure, we performed the Infinium Human Methylation 850K BeadChip measurement in whole blood samples obtained from 15 underground non-uranium miners and 10 matched aboveground control workers. Radon concentrations in the air of workplaces and living environments were measured by CR-39 radon detectors, and annual effective doses were calculated using the detection data. Under the high radon concentration with an average value of 12,700Bq·m-3, a total of 165 significant differentially methylated positions (127 hypermethylated sites and 38 hypomethylated sites) annotated to 71 genes were identified in underground miners (|Δβ| ≥ 0.10, p<0.05), and the average DNA methylation level of 165 DMPs was significantly higher than that of the control workers. Most DMPs were found on chromosome 1, and approximately one-quarter of them were located in genomic promoter regions. Through bioinformatics analysis and pyrosequencing validation, five candidate genes differentially methylated by radon, including TIMP2, EMP2, CPT1B, AMD1 and SLC43A2 were identified. GO and KEGG analysis implicated that long term radon exposure could induce the lung cancer related biological processes such as cell adhesion and cellular polarity maintenance. Our study provides evidence for the alterations of genome-wide DNA methylation profiles induced by long-term high level radon exposure, and new insights into searching for carcinogenic biomarkers of high radon exposure in future studies.

RADON CONCENTRATION MEASUREMENT AND DOSE ESTIMATION IN NON-URANIUM MINES IN CHINA (2019-21).

The radon concentration in selected non-uranium mines from 2019 to 2021 in China are presented. By using of solid-state nuclear track detector, a total of 110 non-uranium mines in 13 provinces and autonomous regions were monitored, and the data were analyzed according to the mineral categories. The arithmetic mean of radon concentration in underground metal mines and nonmetallic mines were 1180 and 162Bq m-3, respectively, and the standard deviations were 2850 and 151Bq m-3, respectively. Correspondingly, the average annual effective dose of metal miners was 12.7mSv and that of nonmetal miners was 1.75mSv. It was noted that the radon concentration in some metal mines is not optimal in China. It is suggested that the ventilation should be strengthened in some metal mines. Besides, it is still necessary to control occupational radon exposure of non-uranium miners as low as reasonably achievable, and non-uranium mines should be managed by classification.

REASSESSMENT OF RADIATION EXPOSURES OF UNDERGROUND NON-URANIUM MINE WORKERS IN WESTERN AUSTRALIA

In the 1990, radon and radon progeny was reported to contribute approximately 70% of the average 1.4+1.0-mSv annual dose across 26 Western Australian underground non-uranium mines. The Western Australian underground mining workforce has expanded significantly, and parameters used to calculate doses have changed significantly, warranting a review of the 1990's data. The review concludes that doses received by the contemporary mining workforce has increased on average, by 5.4%, with annual dose estimates ranging from 0.53 to 3.56mSv, with a mean of 1.33mSv. Doses in 12 of the 23 underground mines exceed 1mSv and are required to comply with radiation safety legislation. It is estimated that 5400 underground workers will fall into the greater than 1-mSv category. The collective dose to the underground worker population has increased by 4.5 times from 3060 man mSv (2173 workers) to 13 669 man mSv (8597 workers).

Current status and strategy of radiological health surveillance for radon and its daughters in non-uranium mine

Current status and strategy of radiological health surveillance for radon and its daughters in non-uranium mine

OCCUPATIONAL EXPOSURE TO RADON IN DIFFERENT KINDS OF NON-URANIUM MINES.

For more accurate assessments of the occupational exposure to radon for miners, the individual monitoring was conducted by using an improved passive integrating (222)Rn monitor. A total of 120 miners in 3 different kinds of mines were monitored throughout a year. The results showed that the individual exposure to radon significantly varied with types of mines and work. Compared with the exposure to coal miners, the exposure to copper miners was much higher. Furthermore, it was found that the exposure might be overestimated if the environmental (222)Rn monitored by the passive integrating monitors was used for assessment. The results indicate that the individual monitoring of radon is necessary for an accurate assessment of radon exposure to miners, and radon exposure to non-uranium miners should also be assessed from the viewpoint of radiation protection.

Моделирование радиационной обстановки в подземных рудниках неурановых предприятий

Моделирование радиационной обстановки в подземных рудниках неурановых предприятий

The Cytokinesis-Block Micronucleus Assay on Peripheral Blood Lymphocytes as a Prospective Biological Test-System to Estimate the Influence of Radon on the Human Organism: Recent Progress and Future Prospects

This paper discusses the problem of assessing the negative after-effects of low doses of ionising radiation exposure in humans. Radon and its decay daughter products are the most widespread source of such irradiation. Miners (in both uranium and non-uranium mines) as well as laypeople in domestic life may be exposed to radon, making the problem of assessing the cytogenetic effects of exposure extremely crucial. One of the more promising test systems to assess the effect of radon is the cytokinesis-block micronucleus assay (CBMN) on peripheral blood lymphocytes, which has a number of advantages over other cytogenetic techniques. Recent progress and future prospects of this cytogenetic method are discussed here.

In vivo measurements of 210Pb in skull and knee geometries as an indicator of cumulative 222Rn exposure in a underground coal mine in Brazil

Cumulative exposure to radon can be evaluated by measuring 210Pb in bone. The skull and knee are two convenient parts of the skeleton for in vivo measuring 210Pb because these regions of the body present a high concentration of bone, the detectors are easily positioned and the likelihood of cross contribution from other organs or tissues is low. A radiological survey of non-uranium mines in Brazil indicated that an underground coal mine in Paraná, located in the south of Brazil, exhibited a high radon concentration. In vivo measurements of 32 underground coal miners were performed in the IRD-CNEN Whole Body Counter shielded room using an array of four high-resolution germanium detectors. Estimations of 210Pb in the total skeleton were determined from direct in vivo measurements of 210Pb in the head and knees. In vivo measurements of 210Pb in 6 out of 32 underground coal miners ranged from 80 to 164 Bq, suggesting that these workers were significantly exposed to 222Rn.

High radon exposure in a Brazilian underground coal mine

The main source of radiation exposure in most underground mining operations is radonand radon decay products. The situation of radon exposure in underground mining inBrazil is still unknown, since there has been no national regulation regarding this exposure.A preliminary radiological survey in non-uranium mines in Brazil indicated that anunderground coal mine in the south of Brazil had high radon concentration and needed tobe better evaluated. This paper intends to present an assessment of radon andradon decay product exposure in the underground environment of this coal miningindustry and to estimate the annual exposure to the workers. As a product ofthis assessment, it was found that average radon concentrations at all samplingcampaign and excavation sites were above the action level range for workplaces of500–1500 Bq m−3 recommended by the International Commission on Radiological Protection—ICRP 65. Theaverage effective dose estimated for the workers was almost 30 times higher than the worldaverage dose for coal miners.

Environmental Radon in Some Brazilian Towns and Mines

In order to assess the natural radioactivity in a developing country with a hot climate, radon concentrations were measured inside 88 dwellings, 34 workplaces, and two underground non-uranium mines belonging to the Brazilian states of Rio Grande do Norte and Ceara. The determinations were performed in the selected settings using solid state nuclear track detectors which were exposed for a period of time of the order of 180 days between the months of June 1995 and April 1996. The indoor radon level was found to range from 3.2 to 140 Bq.m -3 with geometric means of 12.4 Bq.m -3 for houses, and 15.1 Bq.m -3 for workplaces (schools, hospitals, offices, and so on). These relatively low values are probably related to elevated ventilation rates which are typical of edifices located in Northeast Brazil. The average radon concentrations in the surveyed scheelite mines were 153 and 503 Bq.m -3 , respectively.

An investigation into radiation exposures in underground non-uranium mines in Western Australia

A preliminary investigation into the radiological conditions in underground non-uranium mines in Western Australia has been undertaken. Measurements of radon concentration by passive track etch monitors and absorbed gamma dose-rate by thermoluminescent dosimetry were undertaken in 27 mines. These mines employed 2173 workers which represented nearly 80% of the underground workforce at the time of the survey. Radon progeny concentration by both grab sampling and automatic devices were undertaken at selected mines. Radiological conditions in all surveyed underground workplaces were such that it was estimated that most underground workers should not exceed an annual effective dose of 5 mSv. The average annual effective dose across all mines was estimated to be 1.4±1.0 mSv, ranging from 0.4 mSv for a nickel mine to 4.2 mSv for a coal mine. Radon progeny exposure contributed approximately 70% of the total effective dose. The estimated average annual effective dose in three coal mines (employing 297 workers) was 2.9±1.5 mSv. On the basis of this preliminary investigation it was concluded that no regulatory controls are specifically required to limit radiation exposures in Western Australia underground mines.

Computer simulation of radon contamination levels around controlled district recirculation circuits

Research work carried out during the 1960s and 1970s indicated that significant concentrations of radon daughters could be encountered in underground coal, tin, haematite and fluorspar mines as well as in uranium mines. This study indicates that radon-related radiation could occur and constitute a health hazard in non-uranium mines. As a result, research initially concerned with the radon-related contamination in uranium mines was extended to consider the radiation hazard encountered in non-uranium mines, including coal mining. The recent introduction of controlled district recirculation circuits within a number of South African gold mines and a UK coal mine has promoted new interest in assessing the effects that controlled recirculation may have on the levels of radon-related contamination. This paper describes a computer program which was developed in order to predict the possible effect that the introduction of controlled recirculation may have on the residence time and hence radon daughter levels. The results of a series of simulation exercises performed on representative mine ventilation networks are described. These results are compared with available published underground data and general conclusions are presented.

Characterization of the Charge Distribution of Airborne Dust in Canadian Uranium and Non-Uranium Mines

The levels of charge found on airborne dust from various mining and milling operations were measured. More specifically, uranium and non-uranium operations were surveyed, and definite differences in charge distribution were observed. Charge distributions in both types of mines were noted to be symmetrical (net neutral), and while data from non-uranium mines and mills showed good agreement with data gathered by other investigators, uranium mine and mill results seemed to be abnormally low for the types of operations involved. For example, the number of elementary charges associated with 7.5-µm dust was 24 for uranium mines compared with 197 for non-uranium mines at underground primary crusher operations. Similar differences were noted at surface secondary crushing plants where the numbers of charges measured were 15 and 71, respectively, for uranium and non-uranium mills, again for 7.5-µm dust. In an effort to explain these differences, the effects of the level of mechanization, relative humidity, and the ...

Measurement of radon and thoron present in the environment using nuclear track etch detector technique

Abstract The use of solid state nuclear tract detectors (SSNTD) is one of the most convenient techniques to assess the average radiation levels of alpha activities in the environment. This technique has been used to assess the radon and thoron concentrations in some high background areas of South India and underground non-uranium mines in Bihar State. Exposed SSNTD films are chemically etched in an alkali solution and the alpha tracks are evaluated under an optical microscope. The detailed procedure for this study and the calibration of the etched films for conversion of alpha track density to radon and thoron concentrations in pCi l-1 are given in this paper. It was found that 1.9 tracks cm-2 day-1 and 6.2 tracks cm-2 day-1 were produced by exposing the LR-115 foils to 1 pCi l-1 of thoron and radon respectively.

High Airborne Radioactivity Levels Due to Radon in Some Non-Uranium Mines in India

High Airborne Radioactivity Levels Due to Radon in Some Non-Uranium Mines in India

Lung cancer and smoking in a group of iron ore miners.

Several studies have shown that miners, in both uranium and nonuranium mines, have an increased lung cancer mortality, probably caused by exposure to radon and its daughters. The excess mortality has been observed primarily among smoking miners but some recent studies have also indicated a considerably increased risk among nonsmoking miners. This study, among a group of iron ore miners, was undertaken to further elucidate the somewhat unclear and presumably complex relationship of mining, smoking, and lung cancer. The results show a 16-fold increase in lung cancer mortality among miners versus nonminers. Even nonsmoking miners seem to be at a rather high risk of developing lung cancer, but there was a tendency for the most heavy smoking miners to die earlier and to have a slightly shorter induction-latency period for development of lung cancer than was found among the nonsmoking miners.

Does occupational exposure to silica cause lung cancer?

Silica is not generally considered to be a carcinogen, however, occupations characterized by high exposure to crystalline silica have excessive rates of lung cancer mortality. Respiratory cancer excesses have been reported from North America and from Europe for the following dusty trades in which exposure to silica is a common factor: iron and steel foundry workers, steel casting workers, sand blasters, metal molders, non-uranium miners, and ceramic workers. These findings have been reinforced by two reports from the Swedish Pneumoconiosis Register and the Ontario Ministry of Labor indicating that silicotics have statistically significant risks of lung cancer mortality. Animal studies suggest that silica can be an initiating carcinogen or can act as a cocarcinogen or promoter when combined with benzo(a)pyrene. We propose three candidate hypotheses and two pathways for silicocarcinogenesis.

A study on the excretion of Pb-210 and Po-210.

The amount of Po-210 excreted in urine and feces was more influenced by Po-210 that was taken with food and drink than taken through inhalation. The amount of Pb-210 in urine of mining workers among uranium mine workers was higher than that of the non-uranium mine workers. It was thought that this fact was due to the working environment in uranium mine the amount of Pb-210 being a few tens times higher than that in normal environment. The activity ratios of Po-210 of faecal to urinary excretion are widely distributed, however, the average value of many samples approached to 10. Urinary excretion of Po-210 was highest after 24 hours of ingestion, but for faecal excretion, it was highest after 3 days.