Chrysotile Asbestos Mine Research Articles

Mineralogical, Petrological and Geochemical Characterisation of Chrysotile, Amosite and Crocidolite Asbestos Mine Waste from Southern Africa in Context of Risk Assessment and Rehabilitation

Derelict asbestos mine sites in South Africa pose a considerable risk to human, environmental and socio-economic health. Comprehensive mineralogical and geochemical datasets for the existing hazardous geological materials still exposed in Southern African derelict asbestos mines remain largely non-existent, as very little published and up-to-date literature is available. In this study, three representative types of asbestos mineral fibres from derelict asbestos mines in Southern Africa, namely chrysotile from Havelock mine, amosite from Penge mine and crocidolite from Prieska mine, are characterized mineralogically and geochemically to critically evaluate actual hazards in rural and asbestos-fibre-contaminated regions. The samples were examined using polarising light microscopy, X-ray fluorescence (major and trace elemental analysis), X-ray diffraction (including Rietveld refinement), specific surface area analysis and bio-durability testing. Data are discussed in view of their potential toxicities on both human health and the environment in the context of developing countries. Finally, information on the mineralogical and geochemical status of asbestos mine waste and its importance as baseline data for rehabilitation considerations is also evaluated.

НОВЫЕ ФУНКЦИОНАЛЬНЫЕ ВЯЖУЩИЕ МАТЕРИАЛЫ НА ОСНОВЕ СЕРПЕНТИНИТА

Based on the results of the study of composite compositions based on cement and low-temperature silicate hydrate magnesium (based on serpentinite) plasticizing zatvoritelya, salt and acid-basic type, the proposed new areas of recycling enrichment of chrysotile asbestos mine and serpentinite in mineral binding construction materials and for special purposes

A Quantitative Retrospective Exposure Assessment for Former Chrysotile Asbestos Miners and Millers from Baie Verte, NL, Canada.

Despite numerous studies of asbestos workers in the epidemiologic literature, there are very few cohort studies of chrysotile asbestos miners/millers that include high-quality retrospective exposure assessments. As part of the creation of the Baie Verte Miners' Registry in 2008, a two-dimensional job exposure matrix (JEM) was developed for estimating asbestos exposures for former chrysotile asbestos miners/millers. Industrial hygiene data collected between 1963 and 1994 were analysed to assess validity for use in a retrospective exposure assessment and epidemiologic study. Registered former employees were divided into 52 exposure groups (EGs) based on job title and department and mean asbestos concentrations were calculated for each EG. The resulting exposure estimates were linked to individual registrants' work histories allowing for the calculation of cumulative asbestos exposure for each registrant. The distribution of exposure for most EGs (82.6%) could be described as fitting a log-normal distribution, although variability within some EGs (55%) exceeded a geometric standard deviation (GSD) of 2.5. Overall, the data used to create EGs in the development of the JEM were deemed to be of adequate quality for estimating cumulative asbestos exposures for the former employees of the Baie Verte asbestos mine/mill. The variability between workers in the same job was often high and is an important factor to be considered when using estimates of cumulative asbestos exposure to adjudicate compensation claims. The exposures experienced in this cohort were comparable to those of other chrysotile asbestos miners/millers cohorts, specifically Italian and Québec cohorts.

Environmental and Technological Aspects of Acid Treatment of Serpentinite Waste from Chrysotile Asbestos Mining and Processing

Environmental and Technological Aspects of Acid Treatment of Serpentinite Waste from Chrysotile Asbestos Mining and Processing

The risk of cancer in chrysotile asbestos miners and millers

In 2019, with the aim of assessing mortality risks, the formation of the world’s largest cohort of chrysotile asbestos miners and millers was completed at the largest developed chrysotile mine in the world, including a large proportion of working women with extensive data to assess individual exposure and vital status.

Mortality and mesothelioma incidence among chrysotile asbestos miners in Balangero, Italy: A cohort study.

We studied cancer mortality and mesothelioma incidence in 974 male workers employed at least 6 months at the Balangero mine (Italy), the largest chrysotile mine in Western Europe, active from 1917 to 1985. Vital status as of 31 May 2013, causes of deaths and mesothelioma incidence from 1990 were ascertained. Past exposure to asbestos by working area and calendar period was estimated, based on historical data of fibers concentrations. Individual cumulative exposure was assessed by applying estimates to the job history of cohort members. Standardized mortality ratios (SMRs) for selected causes and standardized incidence ratios for malignant mesothelioma (MM) were calculated based on regional reference rates. Poisson regression analysis was used to study MM and lung cancer risk by latency, duration, and cumulative exposure. Mortality was increased for all causes (SMR = 1.28; 95% confidence interval [CI] = 1.17-1.40), pleural cancer (SMR = 4.30; 95% CI = 1.58-9.37), asbestosis (SMR = 375.06; 95% CI = 262.68-519.23). An increase was also found for lung cancer (SMR = 1.14; 95% CI = 0.81-1.55) and peritoneal cancer (SMR = 3.25; 95% CI = 0.39-11.75). The risk of both pleural and peritoneal cancer mortality and of mesothelioma incidence increased with increasing cumulative exposure, duration, and latency. Poisson regression analyses showed an increase in mesothelioma risk with cumulative asbestos exposure and suggest a similar trend for lung cancer. Asbestosis mortality also increased with cumulative exposure. Among Balangero chrysotile miners and millers, the occurrence of malignant and nonmalignant asbestos-related diseases was increased by exposure, with dose-response relation. The study confirms the carcinogenicity of chrysotile asbestos, in particular for pleural mesothelioma.

Mortality from cancer and other causes among Italian chrysotile asbestos miners

ObjectiveTo investigate the long-term mortality of a cohort of Italian asbestos miners.MethodsThe cohort included 1056 men employed in a chrysotile mine between 1930 and 1990, who were followed up during...

CT Characteristics of Pleural Plaques Related to Occupational or Environmental Asbestos Exposure from South Korean Asbestos Mines

ObjectiveThis study evaluated the CT characteristics of pleural plaques in asbestos-exposed individuals and compared occupational versus environmental exposure groups.Materials and MethodsThis study enrolled 181 subjects with occupational exposure and 98 with environmental exposure from chrysotile asbestos mines, who had pleural plaques confirmed by a chest CT. The CT scans were analyzed for morphological characteristics, the number and distribution of pleural plaques and combined pulmonary fibrosis. Furthermore, the CT findings were compared between the occupational and environmental exposure groups.ResultsConcerning the 279 subjects, the pleural plaques were single in 2.2% and unilateral in 3.6%, and showed variable widths (range, 1-20 mm; mean, 5.4 ± 2.7 mm) and lengths (5-310 mm; 72.6 ± 54.8 mm). The chest wall was the most commonly involved (98.6%), with an upper predominance on the ventral side (upper, 77.8% vs. lower, 55.9%, p < 0.001) and a lower predominance on the dorsal side (upper, 74.9% vs. lower, 91.8%, p = 0.02). Diaphragmatic involvement (78.1%) showed a right-side predominance (right, 73.8% vs. left, 55.6%, p < 0.001), whereas mediastinal plaques (42.7%) were more frequent on the left (right, 17.6% vs. left, 39.4%, p < 0.001). The extent and maximum length of plaques, and presence and severity of combined asbestosis, were significantly higher in the occupational exposure group (p < 0.05).ConclusionPleural plaques in asbestos-exposed individuals are variable in number and size; and show a predominant distribution in the upper ventral and lower dorsal chest walls, right diaphragm, and left mediastinum. Asbestos mine workers have a higher extent of plaques and pulmonary fibrosis versus environmentally exposed individuals.

Determination of the concentration of asbestos minerals in highly contaminated mine tailings: An example from abandoned mine waste of Cretaz and Emarese (Valle d'Aosta, Italy)

For the first time, this work reports concentration maps of asbestos minerals in contaminated mine tailings drawn using the results of Rietveld quantitative phase analysis (QPA). The investigated sites are located in the Valle d’Aosta region (Italy): Crètaz, the most important Italian magnetite mine, active until 1979 and Emarèse, one the most important chrysotile asbestos mines in Italy, active until 1968. The results of the study permit to draw the spatial distribution of the asbestos (chrysotile and tremolite in this specific case) concentration, useful to plan reclamation of the sites, with priority given to the areas with the highest asbestos concentration. Because of the complexity of the mineral assemblage, which includes, among the others, antigorite, chlorite, talc, and tremolite, the concentration of chrysotile was cross-checked using different experimental techniques such as X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), polarized light optical microscopy (PCOM), and differential thermal analysis (DTA). The accuracy of the results was validated by analyzing standard samples with known concentrations of chrysotile and tremolite. The comparison allowed to point out the advantages and disadvantages of each experimental method. At Crètaz, chrysotile ranges from 4.4 to 22.8 wt% and tremolite from 1.0 to 10.3 wt%, whereas at Emarèse the concentration of chrysotile varies from 3.3 to 39.5 wt% and tremolite from 5.9 to 12.4 wt%. Antigorite and chlorite are the major accompanying phases with variable amounts of other accessory minerals including magnetite, carbonates, talc, olivine, pyroxene, talc, and brucite. The results of our study are of key importance for the local environmental policies as the knowledge of the spatial distribution of the asbestos concentration allows to plan a detailed reclamation agenda of the contaminated sites. The spots with the highest surface contamination of both chrysotile and tremolite were identified and classified as priority areas in the reclamation plan.

Cancer Mortality in Chinese Chrysotile Asbestos Miners: Exposure-Response Relationships

ObjectiveThis study was conducted to assess the relationship of mortality from lung cancer and other selected causes to asbestos exposure levels.MethodsA cohort of 1539 male workers from a chrysotile mine in China was followed for 26 years. Data on vital status, occupation and smoking were collected from the mine records and individual contacts. Causes and dates of death were further verified from the local death registry. Individual cumulative fibre exposures (f-yr/ml) were estimated based on converted dust measurements and working years at specific workshops. Standardized mortality ratios (SMRs) for lung cancer, gastrointestinal (GI) cancer, all cancers and nonmalignant respiratory diseases (NMRD) stratified by employment years, estimated cumulative fibre exposures, and smoking, were calculated. Poisson models were fitted to determine exposure-response relationships between estimated fibre exposures and cause-specific mortality, adjusting for age and smoking.ResultsSMRs for lung cancer increased with employment years at entry to the study, by 3.5-fold in ≥10 years and 5.3-fold in ≥20 years compared with <10 years. A similar trend was seen for NMRD. Smokers had greater mortality from all causes than nonsmokers, but the latter also had slightly increased SMR for lung cancer. No excess lung cancer mortality was observed in cumulative exposures of <20 f-yrs/ml. However, significantly increased mortality was observed in smokers at the levels of ≥20 f-yrs/ml and above, and in nonsmokers at ≥100 f-yrs/ml and above. A similarly clear gradient was also displayed for NMRD. The exposure-response relationships with lung cancer and NMRD persisted in multivariate analysis. Moreover, a clear gradient was shown in GI cancer mortality when age and smoking were adjusted for.ConclusionThere were clear exposure-response relationships in this cohort, which imply a causal link between chrysotile asbestos exposure and lung cancer and nonmalignant respiratory diseases, and possibly to gastrointestinal cancer, at least for smokers.

A retrospective cohort study of cancer mortality in employees of a Russian chrysotile asbestos mine and mills: Study rationale and key features

Chrysotile, a serpentine asbestos fibre, is the only type of asbestos produced and consumed in the world today. It is an established human carcinogen. We have begun fieldwork on a retrospective cohort study of employees of one of the world's largest chrysotile mine and mills, situated in Asbest, Russia. The primary aim of the study is to better characterize and quantify the risk of cancer mortality in terms of (i) the dose–response relationship of exposure with risk; (ii) the range of cancer sites affected, including female-specific cancers; and (iii) effects of duration of exposure and latency periods. This information will expand our understanding of the scale of the impending cancer burden due to chrysotile, including if chrysotile use ceased worldwide forthwith. Herein we describe the scientific rationale for conducting this study and the main features of its study design.

The dose-response relationship of chrysotile asbestos exposure and lung cancer in cohort study

To clarify the dose-response relationship between asbestos dust exposure and lung cancer incidence in chrysotile asbestos miners by fixed cohort study and to investigate the incidence rates of lung cancer in exposure to different concentrations of asbestos dust. A retrospective cohort study was conducted in 1932 asbestos miners who registered from January 1, 1981 to December 31, 1988, had worked for at least 1 year, and had no obvious cardiopulmonary diseases; the cohort study began in July 2009 and covered a time span of 29 years (1981 - 2009). The personal information, occupational history, disease history, and health data of these miners were recorded, and the monitoring data on dust concentrations in the mine over the years were collected. The dose-response relationship between asbestos dust concentration and lung cancer incidence was established by the method of life table; a regression equation was fitted to predict the excess incidence rates of lung cancer under the conditions of different working years and dust concentrations. A significant dose-response relationship was observed between cumulative exposure (Ce) and cumulative probability (Px) of lung cancer incidence, and the smokers hada higher Px than nonsmokers. When Ce was less than 2000 mg/m(3)·each year, Px reached 6.58/10000; when Ce was not less than 2000 mg/m(3)·and less than 3000 mg/m(3)·each year, Px reached 91.72/10000; when Ce was more than 5000 mg/m(3)·each year, Px was as high as 141.02/10000. The three models were fitted to obtain the optimal regression equation: Px = -0.0004Ce(2) + 0.0052Ce - 0.0011 (r(2) = 0.9387). In the workshop of asbestos mine in this study, the average dust concentration was 85 times higher than the limit in 2009, so the excess incidence rate of lung cancer was 112.598/10000 if the miners worked under this condition for 40 years, according to the equation. There is a significant dose-response relationship between cumulative asbestos exposure and lung cancer incidence in chrysotile asbestos miners. The risk for lung cancer rises as asbestos exposure increases.

Chrysotile asbestos in serpentinite quarries: a case study in Valmalenco, Central Alps, Northern Italy

The Valmalenco serpentinite (Central Alps, Northern Italy) is marketed worldwide as dimension and decorative stone. However, the same area was once subject to chrysotile asbestos mining, from the XIX century until 1975. Asbestos is a well-known carcinogen, and there is the possibility of releasing fibres during quarrying, subsequently exposing workers. From 2004 to 2011, extensive sampling and monitoring of quarry fronts, asbestos veins, commercial stones and airborne asbestos was carried out. Massive rock and vein samples were analyzed by a combined use of optical microscopy, X-ray powder diffraction (XRPD) and quantitative electron microscopy (SEM). Asbestos is concentrated almost exclusively in discrete horizons, that coincide with the main discontinuities of the rock mass. Commercial stones without fractures and veins are practically asbestos free, whereas there is a slight contamination (sometimes exceeding the 1000 ppm threshold) close to hydrothermal selvages. Quarry floors were always quite contaminated by chrysotile "beards" detached from the surface of the blocks. The airborne asbestos concentrations (PCM and SEM) were distributed over a wide range, mostly below the occupational exposure limit of 0.1 f ml(-1). Concentrations at the quarry property border or at the closest villages were always below the environmental exposure limit of 0.002 f ml(-1). The extreme thinness of chrysotile fibrils produced during quarrying activities, and the abundance of pseudo-fibrous antigorite cleavage fragments proved the SEM-EDS analytical procedure to be the most suitable. It is of crucial importance to avoid the interception of veins during quarrying and to remove all visible asbestos from the extracted blocks, before any further processing.

Analysis of mortality in chrysotile asbestos miners in China

In order to investigate the mortality of a cohort of chrysotile asbestos miners in China and evaluate its association with exposure to chrysotile, a fixed cohort of 1932 workers in chrysotile asbestos mine was established in 1981 and followed till June 1, 2010. Information on vital status, cause of death and smoking habits was collected. The workers were divided into two groups according to their exposure status. The exposed group was composed of frontline workers who worked directly on mining or processing asbestos products. The control group consisted of those who were not directly exposed to asbestos in their work. Standardized mortality ratio (SMR) was calculated according to Chinese national death rates. Cox proportional hazards model was applied to estimate the adjusted relative risks of deaths from major causes in exposed and control groups. The results of this study showed that main causes of mortality were malignant neoplasm, cardiovascular disease, cerebrovascular disease and respiratory disease for chrysotile miners. The mortality rate was 939.20 per 100 000 person-years for workers. The SMR for all causes of death was 1.46 in the cohort. Statistically significant mortality excesses were found for lung cancer (SMR=1.51), pulmonary heart disease (SMR=2.70), respiratory disease (SMR=1.93), asbestosis (SMR=9.62), and accident (SMR=1.59). The mortalities from malignant neoplasm, lung cancer, cerebrovascular disease and digestive disease in the exposed group were significantly higher than those in the control group. The findings indicate that chrysotile exposure is a risk factor for lung cancer, respiratory disease, cerebrovascular disease and digestive disease.

Asbestos exposure and mortality in a Chinese miner cohort

ObjectivesAlthough asbestos has been banned in many countries, chrysotile asbestos has continued to be mined and used in China. This study observed cause-specific mortality in a cohort of asbestos miners...

Mortality in a Chinese chrysotile miner cohort

Few data were available to address cause-specific mortality in asbestos miners in China. This study observed a cohort of workers from the largest chrysotile asbestos mine to evaluate the association between asbestos exposure and cause-specific mortality. The cohort consisting of 1,539 male workers was observed from 1981 to 2006. Information on occupational and smoking history and vital status was obtained through personnel records and individual contact. Causes and dates of deaths were verified from hospitals. Workers were divided into two groups: miners and millers (miner group) and control group (not direct exposed). Recent asbestos dust measurements in the workplaces showed that the concentrations ranged from 12 to 197 mg/m(3). Amphibole contamination was very low. Cox proportional hazard models with competing risks were fit to estimate hazard ratios for cause-specific mortality associated with asbestos exposure (miners vs. controls). In addition, standardized mortality ratios (SMRs) were calculated based on national mortality rates. All mortality rates of selected causes, particularly lung cancer, were substantially higher in the miner group than in the controls. SMRs of lung cancer and nonmalignant respiratory diseases in the miners were 4.71 (95% CI, 3.57, 6.21) and 3.53 (2.78, 4.48), respectively. The controls had similar mortality rates of all causes, lung cancer, all cancers as national rates, but a higher mortality from respiratory diseases. Asbestos exposure was related to a 4.6-fold mortality risk for lung cancer and over threefold risk for all cancers and respiratory diseases, while smoking and age were adjusted. The highest SMR of lung cancer was observed in miners who smoked. The results suggested excessive cause-specific mortality, in particular from lung cancer and respiratory diseases, in the cohort, which was associated with exposure to chrysotile asbestos.

Mortality from cancer and other causes in the Balangero cohort of chrysotile asbestos miners

Objectives:To provide further information on mortality from cancer and other causes among chrysotile asbestos miners several years after exposure ceased, we updated the analyses from the Balangero mine worker cohort...

Investing in Global Equities: An Alternative Approach to Structuring Equity Portfolios

<h3>Introduction</h3> A retrospective cohort study of employees of one of the world’s largest chrysotile asbestos mine and mills (JSC Uralasbest, Asbest, Russia) is presently being conducted. The primary aim of the study is to more precisely characterise and quantify the exposure-response relationship for total and site-specific cancer risks associated with chrysotile exposure. <h3>Methods</h3> The study includes workers employed for at least one year during 1975–2010 in the mine, enrichment factories, transportation, laboratory, and the explosives unit. Ascertainment of cohort members through extraction of occupational histories from the enterprises’ archives started in 2012. <h3>Results</h3> At present, the cohort comprises more than 35 000 workers. A detailed occupational history was collected for each cohort member. Temporal trends in exposure levels were analysed using a database containing 89 290 monthly-averaged gravimetric dust concentrations from stationary sampling points in the enrichment factories (1951–2001) and 1457 in the mine (1964–2001). Parallel gravimetric and fibre (PCOM) concentrations were used to estimate dust to fibre conversion factors. Currently a job-exposure matrix is being developed to translate individuals’ job histories into exposure histories for both dust and fibre concentrations. Sverdlovsk region mortality data of cohort members have been ascertained by linkage with medical death certificates recorded at the Sverdlovsk Regional Civil Acts Registration Office. In addition, a comparison of mortality rates in Asbest city and in Sverdlovsk region (1997–2010) was performed. Further efforts are ongoing to ascertain vital status and migration of cohort members from Sverdlovsk region. A parallel cross-sectional survey aimed at estimating tobacco smoking in current workers and veterans (more than 7000 participants) was conducted. <h3>Conclusion</h3> The study will continue through 2019. Given the large size of the cohort, the large proportion of female workers and the detailed exposure data, information obtained in this study will expand knowledge of the cancer burden and prevention potential after chrysotile exposure.

Bioweathering of chrysotile by fungi isolated in ophiolitic sites

Asbestos minerals are commonly found in serpentine rocks and because of the hazard to human health, research has recently focused on possible detoxification strategies. Some fungal species that inhabit serpentine sites (two disused chrysotile asbestos mines in the Western Alps) have been isolated and characterized in order to obtain data on their biodiversity and bioweathering abilities on chrysotile fibres. The three dominant species (Verticillium leptobactrum, Paecilomyces lilacinus and Aspergillus fumigatus) have proved to be able to actively remove iron from chrysotile fibres, V. leptobactrum being the most efficient. A wide range of serpentinicolous fungi release siderophores, iron-chelating compounds, that could play a role in iron extraction from fibres. Iron removal had been correlated previously with a decrease in the toxic potential of fibres, and a biotechnological application of fungi can be envisaged for asbestos detoxification.

The Mine at Baryulgil: Work, Knowledge, and Asbestos Disease

In the period from 1945 until the mid-1970s Australia was a major consumer of asbestos products. Today Australia has one of the world's highest rates of asbestos disease. Local manufacture was dominated by James Hardie Industries which also operated a small chrysotile or white asbestos mine at Baryulgil in northern New South Wales. James Hardie has always claimed that the working and living conditions of its Aboriginal employees were good. However, internal company correspondence and the testimony of miners suggest otherwise. Hardie's refusal to protect its workers from a known risk contributed to a high level of occupational morbidity and mortality, as did ineffective state regulations, the non-union nature of the Baryulgil workplace and the community's isolation.