tremolite and Mesothelioma

This review analytically examines the published data for erionite-related malignant pleural mesothelioma (E-MPM) and any data to support a genetically predisposed mechanism to erionite fiber carcinogenesis. Adult patients of age ≥18 years with erionite-related pleural diseases and genetically predisposed mechanisms to erionite carcinogenesis were included, while exclusion criteria included asbestos- or tremolite-related pleural diseases. The search was limited to human studies though not limited to a specific timeframe. A total of 33 studies (31042 patients) including 22 retrospective studies, 6 prospective studies, and 5 case reports were reviewed. E-MPM developed in some subjects with high exposures to erionite, though not all. Chest CT was more reliable in detecting various pleural changes in E-MPM than chest X-ray, and pleural effusion was the most common finding in E-MPM cases, by both tests. Bronchoalveolar lavage remains a reliable and relatively less invasive technique. Chemotherapy with cisplatin and mitomycin can be administered either alone or following surgery. Erionite has been the culprit of numerous malignant mesothelioma cases in Europe and even in North America. Erionite has a higher degree of carcinogenicity with possible genetic transmission of erionite susceptibility in an autosomal dominant fashion. Therapeutic management for E-MPM remains very limited, and cure of the disease is extremely rare.

Topics: Adult; Asbestos; Asbestos, Amphibole; Environmental Exposure; Female; Humans; Lung Neoplasms; Male; Mesothelioma; Mesothelioma, Malignant; Middle Aged; Pleura; Pleural Effusion; Pleural Neoplasms; Prognosis; Prospective Studies; Retrospective Studies; Tomography, X-Ray Computed; Zeolites

Tremolite is a noncommercial form of amphibole mineral that is present in some chrysotile, talc, and vermiculite deposits. Inhalation of asbestiform tremolite is suspected to have caused or contributed to an increased incidence of mesothelioma in certain mining settings; however, very little is known about the magnitude of tremolite exposure that occurred at these locations, and even less is known regarding tremolite exposures that might have occurred during consumer use of chrysotile, talc, and vermiculite containing products. The purpose of this analysis is to evaluate the exposure-response relationship for tremolite asbestos and mesothelioma in high exposure settings (mining) and to develop estimates of tremolite asbestos exposure for various product use scenarios. Our interpretation of the tremolite asbestos exposure metrics reported for the Thetford chrysotile mines and the Libby vermiculite deposits suggests a lowest-observed-adverse-effect level (LOAEL) for mesothelioma of 35-73 f/cc-year. Using measured and estimated airborne tremolite asbestos concentrations for simulated and actual product use, we conservatively estimated the following cumulative tremolite asbestos exposures: career auto mechanic: 0.028 f/cc-year; non-occupational use of joint compound: 0.0006 f/cc-year; non-occupational use of vermiculite-containing gardening products: 0.034 f/cc-year; home-owner removal of Zonolite insulation: 0.0002 f/cc-year. While the estimated consumer tremolite exposures are far below the tremolite LOAELs derived herein, this analysis examines only a few of the hundreds of chrysotile- and talc-containing products.

Topics: Aluminum Silicates; Animals; Asbestos, Amphibole; Asbestos, Serpentine; Humans; Incidence; Lung Neoplasms; Mesothelioma; Occupational Diseases; Occupational Exposure; Risk Assessment; Talc; Toxicity Tests

Mesothelioma is a malignant tumour of the pleura or peritoneum caused by asbestos. It is increasing in frequency and the prognosis remains grim, with average survival around 1 year.. Medical literature and personal experience.. Amphibole fibres are far more potent than chrysotile in causing mesothelioma.. A minority view suggests that mesotheliomas in those exposed to chrysotile are caused only by tremolite (an amphibole) which contaminates chrysotile. There is a hypothesis, for which evidence is weakening, that Simian virus 40 may cause mesothelioma.. There is emerging evidence of genetic variation in susceptibility to fibre carcinogenesis. There are developments in treatment, particularly chemotherapy with pemetrexed and cisplatin which prolongs survival and helps symptoms.. Targeted agents for treatment are under investigation and may improve the outlook. The role of radical and palliative surgery requires clarification.

Topics: Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Environmental Exposure; Humans; Mesothelioma; Prognosis; Risk Assessment; Risk Factors; Simian virus 40

The main aspects of the sites characterized by environmental exposure to mineral asbestiform fibres are described. Several adverse health effects including high incidence of pleural mesothelioma are reported. The average concentration of airborne fibres is generally low but it rises significantly in association with mechanical disturb of materials with fibres. Multiple sources of exposure have been identified, fibres can be found in the soil and in many materials locally used, mainly in buildings. Three mesothelioma cases were observed in a small rural area of the Basilicata region (Italy). Two of them had a possible occupational exposure to asbestos, the third had a proved environmental exposure to tremolite. This fibre, found in the area, is the same observed in two of the three biological samples analysed.

Topics: Asbestos; Asbestos, Amphibole; Environmental Exposure; Humans; Italy; Mesothelioma; Mineral Fibers; Pleural Neoplasms; Risk Assessment; Rural Population

It has been more than 40 years since occupational crocidolite exposure in South African miners was found to be associated with development of malignant mesothelial tumors 30 to 40 years later. Similar cases were not seen in the amosite and chrysotile miners. Since then, epidemiological and toxicological knowledge have increased enormously, but mortality continues to rise steeply (5% to 10% per year) in most industrialized countries. Even with widespread asbestos abatement efforts, this increase is likely to continue in Western Europe and the United State well into the next century, at least until 2020. Unregulated use of asbestos in less industrialized countries may cause the epidemic to continue throughout the next century in those regions. Asbestos abatement seems to be successful as evidenced by a decline in the proportion of patients with peritoneal tumors, which are the most common malignancies in heavily exposed individuals. Whereas in the 1960s peritoneal tumors comprised up to 30% of the total, in recent years the proportion has fallen to about 10%, This changing ratio could also be due to the steady increase in pleural tumors. The difficulty in formulating the connection as to the etiology of mesothelioma resulted from an unforeseeable difference in the carcinogenicity of various asbestos and mineral fiber types and was compounded by the very long latency of the disease. Unfortunately, the use of a single term, "asbestos," to describe at least five fibrous silicate minerals, each with unique physical, chemical, and biological properties and not infrequently and naturally admixed, severely hampered scientific investigation into the occupational health risks. The field became confused and filled with debate. At the heart of the fiber type controversy lies a fundamentally differing view of the importance of biopersistence of various asbestos fibers in carcinogenesis. This review will deal with the epidemiology of mesothelioma with particular attention to the studies that elucidate the impact of various asbestos fiber types on the etiology of the disease.

Topics: Asbestos; Asbestos, Amphibole; Asbestos, Crocidolite; Case-Control Studies; Cohort Studies; Global Health; Humans; Lung Neoplasms; Mesothelioma; Occupational Diseases; Occupational Exposure; Pleural Neoplasms

Primary malignant mesothelial tumours were recognized by pathologists before asbestiform minerals (chrysotile, crocidolite and amosite) were mined commercially. The discovery, 40 yrs ago, of a causal link with crocidolite and the wide-ranging epidemiological studies which followed are the subject of this review. Early case-control and descriptive surveys, supplemented by cohort studies in insulation workers and chrysotile miners, quickly demonstrated major occupational and geographical differences, with high risk in naval dockyard areas and in the heating trades. In the 1980s, reliable cohort surveys showed that in mining and in the manufacture of asbestos products the mesothelioma risk was much higher when exposure included crocidolite or amosite than chrysotile alone. However, qualitative and quantitative information on exposure was too often inadequate for this evidence to be conclusive. Well-controlled lung fibre analyses have reduced these deficiencies and demonstrated the probable implications of the greater biopersistence of amphibole fibres. Chrysotile for industrial use often contains low concentrations of fibrous tremolite, which may well explain the few cases of mesothelioma associated with this type of asbestos. Progress in this field has been much retarded by controversy, for which the 20 year gap between the availability of reliable estimates of risk for the mining of chrysotile and that for crocidolite or amosite may have been largely responsible.

Topics: Asbestos; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestos, Serpentine; Carcinogens; Case-Control Studies; Cohort Studies; Female; History, 20th Century; Humans; Lung Neoplasms; Male; Mesothelioma; Mineral Fibers; Mining; Occupational Diseases; Reproducibility of Results; Risk Factors

Although tremolite asbestos has been well characterized since 1916, appreciation of its role in disease induction is relatively recent. It has always been understood that the morphology of tremolite is complex, and part of the slowness in recognizing it as a hazard has been definitional in nature. Reduced to simple terms the questions are, when is tremolite "asbestos-like," when is it an innocuous amorphous particle, do these forms occur together, with what confidence can they be separated for regulatory purposes, and what is the spectrum of disease potential for varying exposure? A brake on regulation is partially due to a convergence of opinion of unlikely and unintentional allies: industries producing tremolite-containing materials and some epidemiologists resisting attribution of risk to tremolite on the grounds that its known effects--pleural plaques, asbestosis, lung cancer and mesothelioma--are principally due to chrysotile, which is often contaminated with fibrous tremolite. The latter group concentrate their skepticism on internal-dose biomarker studies associating lung tremolite content with mesothelioma (but not so clearly with lung cancer or asbestosis). They ignore the basic carcinogenic quality of fibrous tremolite, shown in both animal and epidemiological studies. Evidence from the Quebec chrysotile/tremolite mining districts suggests that very low concentrations of tremolite in ambient air can be translated into high concentrations in lung, even in those without occupational exposure. Disease incidence, especially for mesothelioma, seems also to be associated with tremolite air and lung content. The risk associated with tremolite has been demonstrated in Corsica, Cyprus, the United States, and Canada. Of particular importance is an apparent increase in the proportion of mesothelioma risk attributable to tremolite, since the fibers heretofore most responsible for that disease--commercial amphiboles--have been or are being severely regulated or completely eliminated in production and use. Further, amosite and crocidolite, while still a concern, form a small fraction of "asbestos-in-place": most of this material is chrysotile and we do not really know to what degree it is contaminated with tremolite. The available evidence suggests that bulk analysis or airborne fiber analysis will not answer this question, and perhaps only animal bioaccumulation assay is sufficient. Until we know more, it seems prudent for public health to avoid dispersing c

Topics: Animals; Asbestos, Amphibole; Carcinogens; Humans; Lung Neoplasms; Mesothelioma; Mining; Occupational Diseases; Particle Size; Silicic Acid

Topics: Aged; Asbestos; Asbestos, Amphibole; Humans; Lung Neoplasms; Mesothelioma; Middle Aged; Occupational Diseases; Silicic Acid; Silicon Dioxide; Talc

The question of whether chrysotile asbestos ever causes mesothelioma in man has become a major public and occupational health issue. Review of the literature suggests that only 53 acceptable cases of chrysotile-induced mesothelioma have ever been reported; of these, 41 cases have occurred in individuals exposed to chrysotile mine dust, all of it naturally contaminated with tremolite. Ten cases have occurred in secondary industry workers, but here the suspicion of amosite or crocidolite contamination is high. Analysis of lung asbestos content indicates that induction of mesothelioma by chrysotile requires, on average, as great a lung fiber burden as induction of asbestosis by chrysotile, whereas amphibole (amosite or crocidolite)-induced mesotheliomas appear at a several hundred-fold smaller lung burden. Tremolite alone has definitely produced mesothelioma in man, particularly when exposure has been to long, high aspect ratio, fibers. Analysis of tremolite:chrysotile fiber ratios in human lung suggests that some, but not all tremolite is removed in milling chrysotile ores. The low incidence of mesothelioma in secondary chrysotile users may reflect the small amount of tremolite left in the product. These observations indicate that although chrysotile asbestos can produce mesothelioma in man, the total number of such cases is small and the required doses extremely large. The data are consistent with the idea that mesotheliomas seen in chrysotile miners and some secondary industry workers are produced by the tremolite contained in the chrysotile ore, but that the short length and low aspect ratio of the tremolite make its carcinogenicity quite low. However, these data are very indirect, and a role for the chrysotile fiber itself is still possible.

Topics: Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Dose-Response Relationship, Drug; Humans; Lung Neoplasms; Mesothelioma; Mining; Occupational Diseases; Particle Size; Risk Factors; Silicic Acid; Silicon Dioxide; Textile Industry

Asbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends.. Asbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM-EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023.. Asbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011.. The results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011.

Topics: Asbestos; Asbestos, Serpentine; Case-Control Studies; Female; Humans; Lung; Lung Neoplasms; Male; Mesothelioma; Mesothelioma, Malignant; Tumor Microenvironment

Asbestos is a known cause of ovarian cancer. We report 10 cases of serous ovarian cancer among users of Johnson & Johnson (J&J) asbestos-containing "cosmetic" talc products.. We conducted an asbestos exposure assessment during talc application and analyzed surgical tissues and talc containers for asbestos and talc.. Talc was found in all cases and tremolite and/or anthophyllite asbestos was found in 8/10 cases. The asbestos fibers found in the "cosmetic" talc containers matched those found in tissues. We estimated inhaled asbestos dose ranged from 0.38 to 5.18 fiber years.. We provide evidence that the inhaled dose of asbestos/fibrous talc from "cosmetic" talc use causes ovarian cancer. The unique combination of the types of asbestiform minerals detected in cancerous tissue and "cosmetic" talc is a fingerprint for exposure to asbestos-containing talc.

Topics: Asbestos; Asbestos, Amphibole; Cosmetics; Environmental Exposure; Female; Humans; Mesothelioma; Middle Aged; Ovarian Neoplasms; Powders; Talc

The onset of malignant mesothelioma (MM) is linked to exposure to asbestos fibers. Asbestos fibers are classified as serpentine (chrysotile) or amphibole, which includes the crocidolite, amosite, anthophyllite, tremolite, and actinolite types. Although few studies have been undertaken, anthophyllite has been shown to be associated with mesothelioma, and tremolite, a contaminant in talc and chrysotile, is a risk factor for carcinogenicity. Here, after characterizing the length and width of these fibers by scanning electron microscopy, we explored the cytotoxicity induced by tremolite and anthophyllite in cells from an immortalized human mesothelial cell line (MeT5A), murine macrophages (RAW264.7), and in a rat model. Tremolite and short anthophyllite fibers were phagocytosed and localized to vacuoles, whereas the long anthophyllite fibers were caught on the pseudopod of the MeT5A and Raw 264.7 cells, according to transmission electron microscopy. The results from a 2-day time-lapse study revealed that tremolite was engulfed and damaged the MeT5A and RAW264.7 cells, but anthophyllite was not cytotoxic to these cells. Intraperitoneal injection of tremolite in rats induced diffuse serosal thickening, whereas anthophyllite formed focal fibrosis and granulomas on peritoneal serosal surfaces. Furthermore, the loss of Cdkn2a/2b, which are the most frequently lost foci in human MM, were observed in 8 cases of rat MM (homozygous deletion [5/8] and loss of heterozygosity [3/8]) by array-based comparative genomic hybridization techniques. These results indicate that tremolite initiates mesothelial injury and persistently frustrates phagocytes, causing subsequent peritoneal fibrosis and MM. The possible mechanisms of carcinogenicity based on fiber diameter/length are discussed.

Topics: Animals; Asbestos; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestos, Serpentine; Comparative Genomic Hybridization; Cyclin-Dependent Kinase Inhibitor p15; Cyclin-Dependent Kinase Inhibitor p16; Homozygote; Humans; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Rats; Risk Factors; Sequence Deletion

Worldwide studies have been published on the mortality of workers employed in asbestos-based materials for the production of clutches and brakes. However no one of these studies is related to Italian cases. Furthermore, not even surveys have been conducted in Italy to characterize the correlation between asbestos exposures and the possible occurring of asbestos-related disease. Our objectives are the following: i) to assess and quantify the asbestos exposure cases, ii) to describe the nature and the frequency of asbestos-related diseases among blue collar employees of an important factory producing brakes and clutches with chrysotile asbestos content from 1971 to 1993 and iii) to provide preliminary data on cumulative asbestos exposure estimated using lung fibre burden analysis. Critical appraisal of airborne asbestos fibre measurements and identification of cases of asbestos-related diseases between the blue collar employees, either notified to the local health authority or recovered from the Italian national Mesothelioma registry was investigated. Lung fibre burden analysis using the lung tissue samples from two deceased blue collar employees was also performed. Airborne asbestos fibre measurements (carried out in 1982) suggested asbestos fibres average concentrations of about 0.3 f/ml, while all 1992 measurements showed results below 0.1 f/ml. Furthermore, since 1988, we identified four cases of pleural plaques, three cases of asbestosis and seven cases of lung cancer. No case of malignant mesothelioma was found. In both lung cancer cases, analysed to measure the lung fibre burden, commercial amphiboles were absent or in limited concentration but chrysotile and, especially, tremolite asbestos were present in noticeable amount. In conclusion, since 1971 and up to early 1980s, exposure to chrysotile asbestos and talc, likely contaminated by tremolite, had been significant and comparable to levels causing asbestosis long-term risk. No case of malignant mesothelioma was found, that is consistent with the absence of amphiboles and with the lower risk of mesothelioma associated with the chrysotile asbestos. However a subset of the blue collar employees, the ones employed later on, could still have not reached the full risk condition, and so being still at risk of developing malignant mesothelioma. In the two lung cancer cases studied, the lung fibre burden was essentially made of chrysotile and tremolite. Lastly, lung cancer occurrence in the population of b. Nella letteratura scientifica sono presenti studi epidemiologici di mortalità su coorti di lavoratori addetti alla produzione di materiali di attrito in amianto ma non in Italia, dove neppure sono disponibili indagini conoscitive per caratterizzare l’esposizione ad amianto e la possibile presenza di patologie asbesto-correlate. Per questa ragione si è ricostruita la natura e l’entità dell’esposizione ad amianto, la frequenza e la tipologia delle patologie asbesto-correlate in lavoratori di una importante industria di materiali di attrito in asbesto crisotilo utilizzato dal 1971 al 1993; si sono inoltre forniti iniziali elementi per una stima dell’esposizione cumulativa ad asbesto dei lavoratori attraverso l’analisi del carico polmonare di fibre di amianto. Si è operata una valutazione dei monitoraggi ambientali e una rilevazione dei casi di patologie asbesto-correlate diagnosticati tra lavoratori della fabbrica, oltre all’analisi di campioni di tessuto polmonare di due lavoratori per la determinazione del carico residuo di fibre di amianto. Monitoraggi ambientali eseguiti nel 1982 indicavano concentrazioni medie di 0,3 fibre/cc e nel 1992 inferiori a 0,1 fibre/cc per tutti i campioni. Dal 1988 sono stati osservati 4 casi di placche pleuriche, 3 casi di asbestosi, 7 casi di tumore polmonare, nessun caso di mesotelioma maligno. In ambedue i casi di tumore polmonare con analisi delle fibre di amianto gli anfiboli erano assenti o con valori modesti mentre per il crisotilo e soprattutto per la tremolite le concentrazioni rilevate erano consistenti. In conclusione, dagli anni ’70 ai primi anni ’80 l’esposizione ad amianto crisotilo e a talco, in parte contaminati da tremolite, è risultata consistente e compatibile con casi di asbestosi. Non sono stati osservati casi di mesotelioma maligno. Non essendo stati usati anfiboli questo può essere dovuto al più basso rischio di mesotelioma associato al crisotilo, ma parte dei lavoratori assunti in anni successivi potrebbero non essere ancora a pieno rischio. Il carico polmonare di fibre nei due casi di tumore polmonare è essenzialmente dato dal crisotilo e dalla tremolite. La frequenza di tumori polmonari incidenti in questa coorte è verosimilmente sottostimata; il rischio di questa neoplasia dovrebbe essere valutato attraverso uno studio della mortalità della coorte.

Topics: Aged; Air Pollutants, Occupational; Asbestos, Amphibole; Asbestos, Serpentine; Asbestosis; Automobiles; Female; Friction; Humans; Italy; Lung; Lung Neoplasms; Male; Manufacturing Industry; Mesothelioma; Middle Aged; Mineral Fibers; Occupational Exposure; Preliminary Data; Talc; Time Factors

The aim of the study was to reanalyze an updated database of lung asbestos fiber levels for 21 brake repair workers who died of mesothelioma using robust maximum likelihood-based regression methods to address nondetectable measurements.. We applied bivariate normal regression to address the doubly left-censored situation where both the lung fiber concentration of noncommercial (TAA) and commercial amphiboles (AC) were subject to detection limits. For the single left-censored situation, we applied censored normal regression to study the relationship between duration of employment (DOE) and TAA.. We found a statistically significant positive relationship between TAA and AC (β = 0.49, 95% confidence interval [CI], 0.11 to 0.86) and a not statistically significant relationship between DOE and TAA (β = 0.02, 95% CI, -0.03 to 0.06).. Our results provide additional support for the conclusion that exposure to commercial amphibole asbestos, and not chrysotile, is related to the occurrence of mesothelioma among some brake workers.

Topics: Adult; Aged; Asbestos, Amphibole; Automobiles; Humans; Limit of Detection; Lung; Maintenance; Mesothelioma; Middle Aged; Occupational Diseases; Occupational Exposure; Peritoneal Neoplasms; Pleural Neoplasms; Regression Analysis

The length distributions of single fibrils of Coalinga, UICC-B and wet dispersed chrysotile were measured by transmission electron microscopy (TEM). It was found that the distributions significantly diverged above approximately 10 μm (μm) in length, corresponding to differences in published results of animal experiments. This result is in contrast to published data in which counting of an insufficient number of fibers resulted in an erroneous conclusion that the length distribution of Coalinga chrysotile fibrils was indistinguishable from those of other sources of chrysotile. The size distributions of the respirable particle size fractions from acknowledged tremolite asbestos samples were found to be dominated by elongate particles longer than 5 μm that are within the dimensional range of non-asbestiform amphiboles. Prior studies have shown that these elongate particles obscure a correlation between a specific size range of particles and results of animal implantation studies that used tremolite of various morphologies. In the prior studies, a reference protocol was developed from four crushed non-asbestiform amphiboles to differentiate the size range of amphibole particles that correlates with the mesothelioma frequencies observed in the animal studies. In the work reported here, this correlation was tested with TEM analyses of amphiboles from Libby, MT, Sparta, NJ and Homestake mine, Lead, SD, which represent known environmental/occupational situations. Further TEM analyses of the tremolite samples used in the original animal implantation studies have also shown that the numbers of elongate tremolite particles with lengths ≤5 μm implanted into the animals are not correlated with the observed mesothelioma frequencies.

Topics: Animals; Asbestos, Amphibole; Asbestos, Serpentine; Humans; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Microscopy, Electron, Transmission; Mineral Fibers; Minerals; Occupational Exposure; Particle Size; Particulate Matter

The objective of this study is to describe the morphology, molecular structure, and chemistry of amphibole fibers from lung samples from workers in the chrysotile mines at Asbestos and Thetford Mines, Quebec. A fibrous tremolite-actinolite contaminant in an asbestos ore sample from the deposit at Asbestos was used for comparison. Lattice imaging was performed using high-resolution transmission electron microscopy (HRTEM). Silica-rich amorphous coatings (SIRA) that may be related to carcinogenesis are noted on all of the HRTEM photographs of fibers retained in lung, but not on fiber surfaces of the bulk comparison sample. Fibers found in lung samples and in a bulk comparison sample are produced primarily by splitting of thicker crystals and, as such, might not be considered asbestos fibers on the basis of certain mineralogical criteria. Implications of SIRA coatings with respect to carcinogenesis are worthy of further study.

Topics: Air Pollutants, Occupational; Asbestos, Amphibole; Cohort Studies; Lung Neoplasms; Mesothelioma; Microscopy, Electron, Transmission; Miners; Occupational Diseases; Quebec

One of the most significant diseases related to environmental asbestos exposure is malignant mesothelioma (MM). Sivas province is located in the Central Anatolia where asbestos exposure is common. We aimed to study clinical, demographical and epidemiologic features of the patients with MM in Sivas, along with the history of asbestos exposure. In total, 219 patients with MM who were diagnosed in our hospital between 1993 and 2010 were retrospectively analyzed in terms of demographical and clinical features. Rock, soil and house plaster samples were taken from the habitats of those patients and were evaluated with optical microscopy and X-ray diffraction methods. The age of the patients ranged between 18 and 85 years. The male-to-female ratio was 1.4:1. Most of the patients confirmed an asbestos exposure history. The most frequent symptoms of the patients were chest pain (60 %) and dyspnea (50 %). The gap between the start of first symptoms and the diagnosis date was approximately 4 months in average. The plaster materials used in most of the houses were made up of mainly carbonate and silicate minerals and some chrysotile. Ophiolitic units contained fibrous minerals such as serpentine (clino + orthochrysotile) chiefly and pectolite, brucite, hydrotalcite and tremolite/actinolite in smaller amounts. MM is not primarily related to occupational asbestos exposure in our region, and hence, environmental asbestos exposure may be indicted. Yet, single or combined roles and/or interactions of other fibrous and non-fibrous minerals in the etiology of MM are not yet fully understood and remain to be investigated.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Asbestos; Asbestos, Amphibole; Environmental Exposure; Female; Geology; Housing; Humans; Lung Neoplasms; Male; Mesothelioma; Mesothelioma, Malignant; Microscopy, Electron, Scanning; Middle Aged; Turkey; X-Ray Diffraction; Young Adult

Asbestos was abundantly used in industry during the last century. Currently, asbestos confers a heavy social burden due to an increasing number of patients with malignant mesothelioma (MM), which develops after a long incubation period. Many studies have been conducted on the effects of the asbestos types that were most commonly used for commercial applications. However, there are few studies describing the effects of the less common types, or minor asbestos. We performed a rat carcinogenesis study using Japanese tremolite and Afghan anthophyllite. Whereas more than 50% of tremolite fibers had a diameter of < 500 nm, only a small fraction of anthophyllite fibers had a diameter of < 500 nm. We intraperitoneally injected 1 or 10 mg of asbestos into F1 Fischer-344/Brown-Norway rats. In half of the animals, repeated intraperitoneal injections of nitrilotriacetate (NTA), an iron chelator to promote Fenton reaction, were performed to evaluate the potential involvement of iron overload. Tremolite induced MM with a high incidence (96% with 10 mg; 52% with 1 mg), and males were more susceptible than females. Histology was confirmed using immunohistochemistry, and most MMs were characterized as the sarcomatoid or biphasic subtype. Unexpectedly NTA showed an inhibitory effect in females. In contrast, anthophyllite induced no MM after an observation period of 550 days. The results suggest that the carcinogenicity of anthophyllite is weaker than formerly reported, whereas that of tremolite is as potent as major asbestos as compared with our previous data.

Topics: Animals; Asbestos, Amphibole; Carcinogenicity Tests; Cell Transformation, Neoplastic; Female; Lung Neoplasms; Male; Mesothelioma; Mesothelioma, Malignant; Nitrilotriacetic Acid; Particle Size; Rats; Rats, Inbred BN; Rats, Inbred F344; Risk Assessment; Risk Factors; Sex Factors; Time Factors

There is controversy about the potential for dust from the talc mines and mills of New York State to cause mesothelioma. Honda et al. published a study of mortality among New York talc workers and concluded that it was unlikely that the two deaths from mesothelioma were caused by talc ore dust. However, fibers of tremolite and anthophyllite have been found in the lungs of talc workers and Hull concluded that "New York talc exposure is associated with mesothelioma, and deserves further public health attention.". Data concerning additional cases of mesothelioma in the cohort have been posted by NIOSH. I used information from the NIOSH website and the Honda report to analyze the incidence of mesothelioma during the years 1990-2007.. There were at least five new cases of mesothelioma in the cohort and mesothelioma incidence rates were at least five (1.6-11.7) times the rate in the general population (P < 0.01).. I conclude that: (1) mesothelioma has been diagnosed among members of the cohort at a rate in excess of that in the general population; (2) fibers of tremolite and anthophyllite have been detected in dust and the lungs of talc workers; and (3) these fibers are known causes of mesothelioma. It is prudent, on the balance of probabilities, to conclude that dusts from New York State talc ores are capable of causing mesothelioma in exposed individuals.

Topics: Aged; Aged, 80 and over; Antiperspirants; Asbestos; Asbestos, Amphibole; Dust; Humans; Incidence; Male; Mesothelioma; Middle Aged; Mining; National Institute for Occupational Safety and Health, U.S.; New York; Occupational Diseases; Occupational Exposure; Registries; Risk; Risk Factors; Talc; United States

Tremolite contamination has been proposed as the cause of mesothelioma in workers exposed to commercial chrysotile. The asbestos industry and scientists it has sponsored, for example, have argued that commercial chrysotile does not cause peritoneal mesothelioma.. Case report of peritoneal mesothelioma in a mill worker from a tremolite free Canadian mine.. Reports from pathology and occupational health and safety panels conclude that this mill worker developed work-related peritoneal mesothelioma.. Chrysotile without tremolite can cause peritoneal mesothelioma.

Topics: Aged; Asbestos, Amphibole; Asbestos, Serpentine; Fatal Outcome; Humans; Male; Mesothelioma; Occupational Diseases; Occupational Exposure; Peritoneal Neoplasms; Quebec

Asbestos is associated with South African diamond mines due to the nature of kimberlite and the location of the diamond mines in relation to asbestos deposits. Very little is known about the health risks in the diamond mining industry. The objective of this study was to explore the possibility of asbestos exposure during the process of diamond mining.. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis were used to identify asbestos fibres in the lungs of diamond mine workers who had an autopsy for compensation purposes and in the tailings and soils from three South African diamond mines located close to asbestos deposits. The asbestos lung fibre burdens were calculated. We also documented asbestos-related pathological findings in diamond mine workers at autopsy.. Tremolite-actinolite asbestos fibres were identified in the lungs of five men working on diamond mines. Tremolite-actinolite and/or chrysotile asbestos were present in the mine tailings of all three mines. Mesothelioma, asbestosis, and/or pleural plaques were diagnosed in six diamond mine workers at autopsy.. These findings indicate that diamond mine workers are at risk of asbestos exposure and, thus, of developing asbestos-related diseases. South Africa is a mineral-rich country and, when mining one commodity, it is likely that other minerals, including asbestos, will be accidentally mined. Even at low concentrations, asbestos has the potential to cause disease, and mining companies should be aware of the health risk of accidentally mining it. Recording of comprehensive work histories should be mandatory to enable the risk to be quantified in future studies.

Topics: Air Pollutants, Occupational; Asbestos; Asbestos, Amphibole; Asbestosis; Autopsy; Databases as Topic; Diamond; Environmental Monitoring; Epidemiological Monitoring; Female; Humans; Lung; Male; Mesothelioma; Mineral Fibers; Mining; Occupational Exposure; Pleura; Risk Assessment; Soil Pollutants; South Africa; Talc; Workers' Compensation

In the 1960s and 1970s, well designed case-referent studies put beyond doubt that exposure to airborne asbestos fibres was a cause of malignant mesothelioma. Some 35 cohort mortality studies in a large variety of industries during the 20-year period, 1974-1994, showed a wide range of outcomes, but in general that the risk was higher in exposures which included amphiboles rather than chrysotile alone. Real progress began, however, with discoveries along several lines: the link between pleural changes and mineralogy, the concept and importance of biopersistence, the developments in counting and typing mineral fibres in lung tissue, and data on amphibole mining in South Africa and Australia for comparison with that on chrysotile in Canada and Italy. This led to the recognition of the potential contamination in North America of chrysotile with tremolite. A survey in Canada in 1980-1988 and other surveys demonstrated that crocidolite, amosite, and tremolite could explain almost all cases of mesothelioma. Effective confirmation of this was finally achieved with data on vermiculite miners in Libby, Montana, in the years 1983-1999, where exposure was to tremolite-actinolite and/or other amphibole fibres alone.

Topics: Air Pollutants, Occupational; Aluminum Silicates; Asbestos; Asbestos, Amphibole; Canada; Carcinogens; Case-Control Studies; Cohort Studies; Humans; Italy; Lung Neoplasms; Mesothelioma; Mineral Fibers; Mining; North America; Occupational Diseases; Occupational Exposure; Risk Factors; South Africa; United Kingdom; United States

Mediterranean regions such as Greece, Turkey, Cyprus, Corsica and New Caledonia have experienced epidemics of malignant mesothelioma as a result of non-occupational, "domestic" exposure to tremolite asbestos and fibrous erionite. This exposure to tremolite asbestos and fibrous erionite is typified "domestic" due to its prevalence in regions with natural deposits of tremolite asbestos (or fibrous erionite) where the material from tremolite asbestos or fibrous erionite is used for domestic applications such as whitewashing. However, these exposures may be useful in examining the potential consequences of even small amounts of amphibole asbestos fibers in the ambient air. It can also elucidate the effects of fibers that behave like amphibole asbestos. However, this type of exposure is not useful for studying the potential effects of small amounts of asbestos in the ambient air of big cities due to the differing nature of the fiber types and modes of exposure between the regions.

Topics: Air Pollutants; Asbestos, Amphibole; Asbestosis; Calcinosis; Carcinogens, Environmental; Disease Outbreaks; Female; Humans; Male; Mediterranean Region; Mesothelioma; Mineral Fibers; Pleural Diseases; Zeolites

Topics: Administration, Oral; Animals; Asbestos, Amphibole; Carcinogenicity Tests; Carcinogens, Environmental; Cells, Cultured; Disease Models, Animal; Gastrointestinal Neoplasms; Humans; Inhalation Exposure; Lung Neoplasms; Mesothelioma; Mineral Fibers; Organ Culture Techniques; Risk Assessment

Topics: Asbestos, Amosite; Asbestos, Amphibole; Carcinogens, Environmental; Female; Humans; Male; Mediterranean Region; Mesothelioma; Mineral Fibers; Minnesota; South Africa

Vermiculite from the mine near Libby, Montana, is contaminated with tremolite asbestos and other amphibole fibers (winchite and richterite). Asbestos-contaminated Libby vermiculite was used in loose-fill attic insulation that remains in millions of homes in the United States, Canada, and other countries.. This report describes asbestos-related occupational respiratory disease mortality among workers who mined, milled, and processed the Libby vermiculite.. This historical cohort mortality study uses life table analysis methods to compare the age-adjusted mortality experience through 2001 of 1,672 Libby workers to that of white men in the U.S. population.. Libby workers were significantly more likely to die from asbestosis [standardized mortality ratio (SMR) = 165.8; 95% confidence interval (CI), 103.9-251.1], lung cancer (SMR = 1.7; 95% CI, 1.4-2.1), cancer of the pleura (SMR = 23.3; 95% CI, 6.3-59.5), and mesothelioma. Mortality from asbestosis and lung cancer increased with increasing duration and cumulative exposure to airborne tremolite asbestos and other amphibole fibers.. The observed dose-related increases in asbestosis and lung cancer mortality highlight the need for better understanding and control of exposures that may occur when homeowners or construction workers (including plumbers, cable installers, electricians, telephone repair personnel, and insulators) disturb loose-fill attic insulation made with asbestos-contaminated vermiculite from Libby, Montana.

Topics: Aged; Aluminum Silicates; Asbestos, Amphibole; Asbestosis; Cohort Studies; Humans; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Mining; Montana; Occupational Exposure; Pleural Neoplasms; Retrospective Studies

Environmental asbestos exposure is reportedly common in some districts of Turkey. The aim of this study was to investigate the presence and effect of environmental asbestos exposure in a village in Gaziantep, Turkey, with reported cases of mesothelioma.. All villagers > or =14 years old were subject to an interview rediagnosis and a detailed questionnaire. Chest microfilms were performed in all cases, and additional standard CXRs were obtained when necessary. Samples collected from the natural mantle, and whitewash from the houses were analysed for the presence of asbestos.. In total, 269 villagers took part in the study. The incidence of histopathologically diagnosed malignant pleural mesothelioma was 0.32% relative to the total village population in the year 2000. The verbal autopsy revealed eight possible cases of malignant pleural mesothelioma, all of whom had died within the past 12 years. Of these eight, there was a first-degree kinship between three, and additionally, these patients had a third-degree relationship with a biopsy proven case. Radiological evaluation showed pleural calcification and/or thickness in 3.3%, and pleural effusion in 0.4% of patients undergoing CXR. All houses in the village were constructed using adobe soil, and the interior whitewash was made from soil containing asbestos. Analysis of soil samples revealed tremolite and/or actinolyte asbestos.. The current findings suggest that environmental asbestos exposure continue to be a serious health concern in the Gaziantep region of Turkey.

Topics: Adult; Aged; Asbestos; Asbestos, Amphibole; Biopsy; Environmental Exposure; Female; Humans; Incidence; Lung; Male; Mesothelioma; Middle Aged; Occupational Exposure; Pleural Neoplasms; Radiography, Thoracic; Turkey

Topics: Asbestos, Amphibole; Environmental Exposure; Epidemiologic Studies; Humans; Mesothelioma; Risk Assessment

The progress of pleural plaques in persons exposed to environmental asbestos in Almopia, Greece were studied prospectively.. During a 15-year period, 198 individuals, in whom pleural plaques had been observed during the period 1988-1990 were followed. Respiratory function was initially evaluated in 23. All were inhabitants of seven villages of Northern Greece, where rocks with high concentration in asbestos fibers were used for whitewashing until 1935.. Out of this population, 126 survived and underwent chest X-ray in 2003 while respiratory function was retested in 18. New radiological findings were compared to previous ones using digital technology. Furthermore, the cause of death of the remaining 72 was recorded. Deterioration of X-ray findings was observed in all survivors. Not only did the surface area of previous plaques increase (8.66 +/- 12.6 cm2, mean value +/- SD) but new ones also appeared. Total lung capacity decreased from 95.6 +/- 14.8 in 1998 to 76.5 +/- 9.3% predicted in 2003. It was found that out of 72 deaths, 11 people died of malignant lung neoplasm, and 4 of mesothelioma.. Radiological appearance of pleural plaques and respiratory function of people previously exposed to asbestos environmental pollution worsens over the years. Prevalence of mesothelioma was found to be higher than expected.

Topics: Adult; Aged; Asbestos; Asbestos, Amphibole; Disease Progression; Environmental Exposure; Female; Greece; Humans; Male; Mesothelioma; Pleura; Pleural Diseases; Prospective Studies; Rural Population; Time Factors

Topics: Animals; Asbestos, Amphibole; California; Dogs; Environmental Exposure; Humans; Mesothelioma; Montana; Respiratory Tract Diseases; Risk Assessment; United States; United States Environmental Protection Agency

Topics: Asbestos, Amphibole; Costs and Cost Analysis; Environmental Exposure; Environmental Pollution; Humans; Mesothelioma; Montana; Public Health; United States; United States Environmental Protection Agency

Twenty years ago, we reported on a very high prevalence of pleural calcifications (PCs) and malignant mesothelioma among inhabitants of Metsovo, in northwestern Greece. It was shown that both abnormalities were related to asbestos exposure from a whitewash containing tremolite. The fading use of this material has resulted in a decreased incidence of mesothelioma (one third of the original incidence). The aim of the present study was to examine whether PCs among Metsovites has followed a similar trend.. Retrospective study.. University Hospital of Ioannina, a tertiary teaching hospital, "G. Hadjikosta" Hospital, a tertiary hospital in Ioannina, and Metsovo Health Center, a primary care center in the town of Metsovo.. Chest roentgenograms of 307 Metsovites, obtained between from 1998 to 2002 were examined. The prevalence of PCs was compared to the one noted 20 years ago.. A significantly lower prevalence of calcifications was observed now among younger Metsovites (< 60 years of age). In both studies, there was an increasing rate of PC with age.. The findings of the present study strengthen the incrimination of the whitewash containing tremolite in the development of PCs in Metsovites. The withdrawal of its use in the area has resulted in a null prevalence of PCs in individuals < 40 years old.

Topics: Adult; Aged; Asbestos; Asbestos, Amphibole; Calcinosis; Environmental Exposure; Female; Greece; Humans; Male; Mesothelioma; Middle Aged; Pleural Diseases; Pleural Neoplasms; Prevalence; Retrospective Studies

Lung tissue from 15 women who died from mesothelioma was evaluated for tissue burden of ferruginous bodies and uncoated asbestos fibers. The group contained individuals who had occupational exposure to asbestos and others had family members whose work history included vocations where contact with asbestos containing materials occurred.. Tissue samples from tumor free lung were digested and filtered and then investigated for ferruginous bodies by light microscopy and asbestos and non-asbestos fibers by analytical transmission electron microscopy (ATEM). Size and type of fibers were also analyzed.. Asbestos bodies were found in 13 of the 15 samples and asbestos fibers were found in all cases. The most commonly found uncoated asbestos fiber in these individuals was amosite whereas tremolite was the second most commonly found form. The asbestos fiber burden in these females was often of mixed types.. The asbestos body and fiber burden in these cases show variation in tissue burden. Some cases in this study had appreciable burden, which was attributed to secondhand exposure from occupationally exposed family members. Mesothelioma can occur also in individuals with comparatively low tissue burdens of asbestos.

Topics: Aged; Aged, 80 and over; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestosis; Body Burden; Environmental Exposure; Female; Humans; Lung; Lung Neoplasms; Mesothelioma; Microscopy, Electron; Middle Aged; Mineral Fibers; Occupational Exposure; Reproducibility of Results

Topics: Amphibians; Animals; Asbestos, Amphibole; California; Environmental Exposure; Environmental Monitoring; Epidemiological Monitoring; Humans; Mesothelioma; Mining; Public Health; Respiratory Tract Diseases; Risk Assessment; Toxicity Tests

Exposure to chrysotile dust has been associated with the development of mesothelioma and recent studies have implicated contaminating tremolite fibers as the likely etiological factor. Tremolite also contaminates talc, the most common non-asbestos mineral fiber in our control cases.. We examined 312 cases of mesothelioma for which fiber burden analyses of lung parenchyma had been performed by means of scanning electron microscopy to determine the content of tremolite, non-commercial amphiboles, talc and chrysotile. The vast majority of these patients were exposed to dust from products containing asbestos.. Tremolite was identified in 166 of 312 cases (53%) and was increased above background levels in 81 cases (26%). Fibrous talc was identified in 193 cases (62%) and correlated strongly with the tremolite content (P < 0.0001). Chrysotile was identified in only 32 cases (10%), but still correlated strongly with the tremolite content (P < 0.0001). Talc levels explained less of the tremolite deviance for cases with an increased tremolite level than for cases with a normal range tremolite level (22 versus 42%). In 14 cases (4.5%) non-commercial amphibole fibers (tremolite, actinolite and/or anthophyllite) were the only fiber types found above background.. We conclude that tremolite in lung tissue samples from mesothelioma victims derives from both talc and chrysotile and that tremolite accounts for a considerable fraction of the excess fiber burden in end-users of asbestos products.

Topics: Aged; Asbestos, Amphibole; Female; Humans; Male; Mesothelioma; Middle Aged; Occupational Diseases; Occupational Exposure

Inhabitants of Metsovo in northwest Greece have been exposed to asbestos from use of a tremolite-containing whitewash ("luto" soil). As a result, they have increased incidence of malignant pleural mesothelioma and pleural calcifications (PCs). However, subjects with calcifications have a much lower incidence of mesothelioma than those without. A previous study of the two groups with BAL revealed higher proportional lymphocytosis among subjects with calcifications. We suggested that BAL lymphocytosis may be somehow correlated with "protection" against neoplasia.. The present report is a study of the liquid phase of BAL in the two groups. BAL specimens of 43 Metsovites (13 subjects with PCs and 30 subjects without PCs) and two control groups were examined. We measured total protein, albumin, IgG, IgA, and interleukin-6. Proteins were analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional electrophoresis and further characterized using an appropriate computer program.. The most interesting finding was the presence of two additional protein spots corresponding to the electrophoretic site of Ig heavy chain and C(4) component of complement. The two proteins were present in all Metsovites with PCs but in none without PCs and also in none of the control groups.. This study further separates two groups of Metsovites with different reaction to asbestos, possibly as a result of different activation of alveolar macrophages. This difference leads the first group to the formation of PCs, BAL fluid lymphocytosis, and relative "protection" against malignancy, and the second group to no calcifications, no lymphocytosis, but also no protection against malignancy.

Topics: Adult; Aged; Asbestos, Amphibole; Asbestosis; Bronchoalveolar Lavage Fluid; Calcinosis; Complement C4; Environmental Exposure; Female; Greece; Humans; Immunoglobulin A; Immunoglobulin G; Immunoglobulin Heavy Chains; Interleukin-6; Lymphocytosis; Male; Mesothelioma; Middle Aged; Pleural Diseases; Pleural Neoplasms; Prognosis; Proteins

The high incidence of malignant mesothelioma in some villages of Cappadocia (Turkey) is due to environmental exposure to erionite fibres. The aim was to evaluate the fibre burden in bronchoalveolar lavage fluid (BALF) from inhabitants of an erionite village and compare it with Turkish subjects with or without environmental exposure to tremolite asbestos.. Ferruginous bodies (FBs) and fibres were measured and analyzed by light and transmission electron microscopy (TEM) in the BALF of 16 subjects originating from Tuzköy.. FBs were detected in the BALF of 12 subjects, with concentrations above 1 FB/ml in seven of them. Erionite was the central fibre of 95.7% of FBs. Erionite fibres were found in the BALF of all subjects, by TEM, and these fibres were low in Mg, K, and Ca compared with erionite from Tuzköy soil. The mean concentration of erionite fibres in BALF was similar to that of tremolite fibres in Turks with environmental exposure to tremolite. The proportion of fibres longer than 8 microm in BALF represented 35.6% for erionite compared with 14.0% for tremolite. The asbestos fibre concentrations in erionite villagers was not different from that in Turks without environmental exposure to tremolite.. Analysis of BALF gives information about fibre retention in populations environmentally exposed to erionite for whom data on fibre burden from lung tissue samples are scarce. This may apply to exposed Turks having emigrated to other countries.

Topics: Adult; Asbestos, Amphibole; Body Burden; Bronchoalveolar Lavage Fluid; Case-Control Studies; Environmental Exposure; Female; Humans; Male; Mesothelioma; Microscopy, Electron; Middle Aged; Mineral Fibers; Peritoneal Neoplasms; Pleural Neoplasms; Soil Pollutants; Turkey; Zeolites

Environmental exposure to tremolite and erionite causes endemic diseases of the lung and pleura in Turkey. This study aimed to evaluate the impact of these exposures and further occupational exposures on fibre-related diseases in Turkish immigrants living in Belgium. The study included 51 males and 17 females that emigrated < 1-38 yrs ago. Most of them (n=46) had nonmalignant pleural lesions, one had asbestosis and one had mesothelioma. Environmental asbestos exposure was likely for the majority of patients (60%), but there were also reports of possible occupational asbestos (n = 14) and erionite (n = 2) exposure. Tremolite was the main fibre type in bronchoalveolar lavage fluid (BALF). Elevated concentrations of amosite or crocidolite were detected in only two patients. The delay elapsed since the end of the environmental exposure had no influence on the asbestos body or the tremolite fibre concentrations in the BALF of Turkish immigrants. Most fibre-related diseases in Turkish immigrants are probably due to environmental rather than occupational exposure. Precise information about geographical origin and occupation should be obtained when investigating these patients. Mineralogical analysis of bronchoalveolar lavage fluid gives valuable information on the type and intensity of exposure, especially in patients with both environmental and occupational exposure.

Topics: Adult; Aged; Asbestos, Amphibole; Asbestosis; Belgium; Emigration and Immigration; Environmental Exposure; Female; Humans; Male; Mesothelioma; Middle Aged; Mineral Fibers; Occupational Exposure; Pleural Neoplasms; Pneumoconiosis; Turkey; Zeolites

Mining and processing of amphibolite is associated with workers' exposure to dust containing asbestos minerals (actinolite, tremolite) and with the presence of respirable fibers, i.e. small particles above 5 microns long and below 3 microns in diameter (with length-to-diameter ratio higher than 3:1). Results of epidemiological and laboratory studies show that such dust may be responsible for the development of cancer in dust-exposed people. This work reports the measurement results of concentrations of total dust, respirable fibers and mineral composition of samples collected in plant mining and processing amphibolite rock. Based on the results, cumulated exposure was calculated for the 10-, 20- and 30-year exposure periods. The cumulated exposure was classified into two categories: 0.1-1.0 f/cm3 years and 1.0-10 f/cm3. x years. It has been found that mining and processing of amphibolite is associated with increased risk of death from mesothelioma--11.2 x 10(-5) (crushers--10 years of exposure) to 240.0 x 10(-5) (miners--30 years of exposure). The risk of excessive mortality from lung cancer was not high (below 1. x 10(-4)) for all workplaces and periods of exposure.

Topics: Adult; Asbestos, Amphibole; Carcinogens; Dust; Environmental Monitoring; Humans; Lung Neoplasms; Maximum Allowable Concentration; Mesothelioma; Mining; Occupational Exposure; Poland; Risk Assessment; Time Factors

A case-control study on respiratory cancers was conducted in New Caledonia (South Pacific), where a high incidence of malignant pleural mesothelioma had been observed. The disease pattern suggested an environmental exposure to asbestos. The first results showed that, in some areas, tremolite asbestos derived from local outcroppings was used as whitewash (locally named "pö"). All cases diagnosed between 1993 and 1995 (including 15 pleural mesotheliomas, 228 lung cancers, and 23 laryngeal cancers) and 305 controls were included in the study. Detailed information on past or present use of the whitewash, residential history, smoking, diet, and occupation was collected. The risk of mesothelioma was strongly associated with the use of the whitewash (odds ratio (OR) = 40.9; 95% confidence interval (CI): 5.15, 325). All Melanesian cases had been exposed. Among Melanesian women, exposure to the whitewash was associated with an increased risk of lung cancer (OR = 4.89; 95% CI: 1.13, 21.2), and smokers exposed to po had an approximately ninefold risk (OR = 9.26; 95% CI: 1.72, 49.7) compared with women who never smoked and had never used the whitewash. In contrast, no association was noted between exposure to pö and lung cancer risk among Melanesian men, probably because of lower exposure levels. Among non-Melanesians, the numbers of exposed subjects were too small to assess the effect of exposure to po. There was no indication of elevated risks for the other cancer sites.

Topics: Adolescent; Adult; Asbestos, Amphibole; Case-Control Studies; Environmental Exposure; Female; France; Humans; Male; Mesothelioma; Respiratory Tract Neoplasms

The health effects of asbestos are intimately related to the fate of inhaled fibers in the lungs. The kinetics of asbestos fibers have been studied primarily in rodents. The objective of this study was to explore the application of these kinetic models to human autopsy data.. We analyzed the asbestos fiber content of the lungs of 72 Quebec chrysotile miners and millers and 49 control subjects using analytical transmission electron microscopy. Statistical methods included standard multivariate linear regression and locally weighted regression methods.. The lung burdens of asbestos bodies and chrysotile and tremolite fibers were correlated, as were the concentrations of short, medium, and long fibers of each asbestos variety. There were significant associations between the duration of occupational exposure and the burdens of chrysotile and tremolite. The concentration of chrysotile decreased with the time since last exposure but the concentration of tremolite did not. The clearance rate varied inversely with the length of chrysotile fibers. For fibers greater than 10 mu in length the clearance half-time was estimated to be 8 years.. The patterns in our data are compatible with both of the hypotheses suggested from rodent experiments; the existence of a long-term sequestration compartment and overload of clearance mechanisms in this compartment.

Topics: Aged; Aged, 80 and over; Asbestos, Amphibole; Asbestos, Serpentine; Asbestosis; Case-Control Studies; Humans; Lung Neoplasms; Male; Mesothelioma; Metabolic Clearance Rate; Microscopy, Electron; Middle Aged; Mineral Fibers; Mining; Multivariate Analysis; Regression Analysis

Recently published analyses have shown that the risks of mesothelioma and lung cancer in Quebec chrysotile miners and millers were related to estimated level of fibrous tremolite in the mines where they had worked. An analysis has therefore been made of radiographic changes in men who in 1965 were employed by companies in Thetford Mines where the same question could be examined for fibrogenicity. Of 294 men who met the necessary requirements, 129 had worked in six centrally located mines, where the tremolite content was thought to be high, 81 in 10 peripheral mines where it was thought to be low and 84 in both. The median prevalence of small parenchymal opacities (> or = 1/0) in chest radiographs read by six readers was higher among men ever than never employed in the central mines (13.6% against 7.4%), despite the fact that the mean cumulative exposure was lower in the former (430 mpcf.y vs 520 mpcf.y). After accounting by logistic regression for cigarette smoking, age, smoking-age interaction and cumulative exposure, the adjusted odds ratio for central mine employment was 2.44 (95% lower bound: 1.06). Together with other surveys of asbestos miners and millers, this study suggests that amphibole fibres, including tremolite, are more fibrogenic than chrysotile, perhaps to the same extent that they are carcinogenic, though the data available were not sufficient to address the latter question.

Topics: Aged; Asbestos, Amphibole; Asbestos, Serpentine; Cohort Studies; Humans; Lung; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Mining; Occupational Exposure; Occupational Health; Odds Ratio; Radiography, Thoracic; Risk Assessment

Using light and electron microscopy analysis, as well as electron diffraction, and energy-dispersive x-ray analysis, an aliquot of UICC chrysotile B was analyzed with special attention given to any tremolite contamination. Polarized light microscopy, with its limit of detection of approximately 1 micron when using dispersion staining, revealed chrysotile as the only fibrous asbestos component. Analytical electron microscopy at 333,000x of more than 20,000 consecutive fibers showed only the tubular morphology characteristic of chrysotile. These findings highlight that when this sample was used for exposure disease induced in animal models correlates with chrysotile-induced pathology, and does not support an explanation based on the "amphibole hypothesis." Thus, chrysotile should be considered as having the biologic ability to produce cancers, including mesotheliomas, based on the extensive use of this material as a standard reference material.

Topics: Asbestos, Amphibole; Asbestos, Serpentine; Carcinogens; Humans; Lung Neoplasms; Mesothelioma; Microscopy, Electron; Reference Values; Sensitivity and Specificity

In a cohort of some 11,000 men born 1891-1920 and employed in the Quebec chrysotile production industry, including a small asbestos products factory, of 9780 men who survived into 1936, 8009 are known to have died before 1993, 38 probably from mesothelioma--33 in miners and millers and five in factory workers. Among the 5041 miners and millers at Thetford Mines, there had been 4125 deaths from all causes, including 25 (0.61%) from mesothelioma, a rate of 33.7 per 100,000 subject-years; the corresponding figures for the 4031 men at Asbestos were eight out of 3331 (0.24%, or 13.2 per 100,000 subject-years). At the factory in Asbestos, where all 708 employees were potentially exposed to crocidolite and/or amosite, there were 553 deaths, of which five (0.90%) were due to mesothelioma; the rate of 46.2 per 100,000 subject-years was 3.5 times higher than among the local miners and millers. Six of the 33 cases in miners and millers were in men employed from 2 to 5 years and who might have been exposed to asbestos elsewhere; otherwise, the 22 cases at Thetford were in men employed 20 years or more and the five at Asbestos for at least 30 years. The cases at Thetford were more common in miners than in millers, whereas those at. Asbestos were all in millers. Within Thetford Mines, case-referent analyses showed a substantially increased risk associated with years of employment in a circumscribed group of five mines (Area A), but not in a peripherally distributed group of ten mines (Area B); nor was the risk related to years employed at Asbestos, either at the mine and mill or at the factory. There was no indication that risks were affected by the level of dust exposure. A similar pattern in the prevalence of pleural calcification had been observed at Thetford Mines in the 1970s. These geographical differences, both within the Thetford region and between it and Asbestos, suggest that the explanation is mineralogical. Lung tissue analyses showed that the concentration of tremolite fibres was much higher in Area A than in Area B, a finding compatible with geological knowledge of the region. These findings, probably related to the far greater biopersistence of amphibole fibres than chrysotile, have important implications in the control of asbestos related disease and for wider aspects of fibre toxicology.

Topics: Aged; Aged, 80 and over; Asbestos; Asbestos, Amphibole; Humans; Logistic Models; Lung; Male; Mesothelioma; Occupational Diseases; Odds Ratio; Quebec

It has been suspected for many years that amphibole fibres in the tremolite series, a low level contaminant of chrysotile asbestos, may contribute disproportionately to the incidence of mesothelioma and perhaps other exposure-related cancers. A cohort of some 11,000 Quebec chrysotile workers, 80% of whom have now died, provided the opportunity to examine this hypothesis further. An analysis was made of deaths from mesothelioma (21), cancers of the lung (262), larynx (15), stomach (99), and colon and rectum (76), in men employed by the largest company in Thetford Mines, with closely matched referents. Risks were estimated by logistic regression for these five cancers in two groups of mines--five mines located centrally and ten mines located peripherally; tremolite contamination had been demonstrated to be some four times higher in the former than in the latter. Odds ratios for work in the central mines were raised substantially and significantly for mesothelioma and lung cancer, but not for the gastric, intestinal or laryngeal cancer sites. In the peripheral mines, there was little or no evidence of increased risk for any of the five cancers. The hypothesis that, because of the difference in distribution of fibrous tremolite, cancer risks in the central area would be greater than in the periphery was thus substantiated. That the explanation may lie in the greater biopersistence of amphibole fibres than chrysotile is important in framing policies for the use and control of asbestos and is directly relevant to the selection of man-made mineral fibre substitutes.

Topics: Aged; Aged, 80 and over; Asbestos, Amphibole; Asbestos, Serpentine; Case-Control Studies; Coal Mining; Humans; Logistic Models; Male; Mesothelioma; Neoplasms; Occupational Diseases; Odds Ratio; Quebec

About 8% of our cases of mesothelioma occur in women, with a median age of 59 years. Our percentage is lower than other series reported in the literature because of the large number of occupationally exposed men referred to our laboratory. Tumor arose in the pleura in 86% of the women in our study, and the majority were epithelial. Pleural plaques were found in half of the women for which this information was available, and asbestosis was found in only 16%. A history of exposure to asbestos was identified in three quarters of the women, more than half of whom were household contacts of asbestos workers. Occupational exposure to asbestos was identified in only 19% of patients. An elevated tissue asbestos burden was noted in 70% of women from whom lung tissue was available for analysis. The main fiber type identified was amosite, followed by tremolite and chrysotile. These findings and those from other countries suggest a need for reassessment of the background rate of mesothelioma in industrialized nations.

Topics: Adult; Aged; Aged, 80 and over; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Serpentine; Asbestosis; Female; Humans; Male; Mesothelioma; Middle Aged; Mineral Fibers; Peritoneal Neoplasms; Peritoneum; Pleura; Pleural Neoplasms

Inhabitants of the Metsovo area, north-west Greece have been exposed since childhood to inhalation of asbestos, from a material containing tremolite, used for whitewashing ("luto soil"). This has resulted in endemic pleural calcifications (47% of adult population) and increased incidence of malignant pleural mesothelioma (MPM). In 1987, we reported that the incidence of MPM between 1981-1985 was around 300 times higher than expected in a nonasbestos exposed population (seven cases in 5 yrs in a population of 4,000-5,000). The present study is an updated report regarding this "mesothelioma epidemic", in conjunction with the diminished use and final abandonment of "luto soil" in the early 1980s. It appears that the incidence of MPM in Metsovo has dropped considerably since our first report. Between 1985-1994, we diagnosed six such cases (incidence rate = 1.4 cases per 10,000 person-years), whilst between 1980-1984 eight cases had been diagnosed (incidence rate = 3.7 cases per 10,000 person-years). Although, because of the small number of cases, this did not reach statistical significance (p = 0.08), we note that the incidence is now considerably lower than before. Had it remained unchanged, we would have expected 17 cases of MPM instead of six. This drop follows the diminished use of "luto" whitewash (by 92% of the population in 1950 and only 18% in 1980). If we take into account a 30-40 year latency period for mesothelioma, we expect that the "Metsovo mesothelioma epidemic" will fade away by the year 2020-2030, since the material has not been used since 1985.

Topics: Adult; Aged; Asbestos; Asbestos, Amphibole; Chi-Square Distribution; Environmental Exposure; Female; Greece; Humans; Incidence; Male; Mesothelioma; Middle Aged; Pleural Neoplasms; Risk Factors

After several cases of malignant pleural mesothelioma (MPM) were detected in the village of Kureyşler in the Kütahya district of western Turkey, an epidemiological study was conducted. A questionnaire was completed by 124 villagers who were older than 20 years and standard posteroanterior chest X-rays were taken. The films were evaluated by three chest physicians. Samples of the white stucco that had been used by almost all villagers for indoor painting for many years were mineralogically examined. Chest X-rays showed that 23 (18%) had pleural plaques and calcifications compatible with asbestos exposure. Male sex and old age were associated with occurrence of pleural plaques. An analysis of white stucco samples revealed tremolite asbestos. In conclusion, tremolite fibers might be the cause of the high incidence of pleural plaques and MPM cases in the village of Kureyşler.

Topics: Adult; Aged; Air Pollutants; Asbestos, Amphibole; Female; Humans; Male; Mesothelioma; Middle Aged; Pleural Neoplasms; Rural Population; Turkey

Topics: Asbestos, Amphibole; Asbestos, Serpentine; Cohort Studies; Humans; Lung Neoplasms; Male; Mesothelioma; Mining; Occupational Diseases; Occupational Exposure; Quebec; Time Factors

Twenty cases of mesothelioma among miners of the township of Asbestos, Quebec, Canada, have been reported. To further explore the mineral characteristics of various fibrous material, we studied the fibrous inorganic content of postmortem lung tissues of 12 of 20 available cases. In each case, we measured concentrations of chrysotile, amosite, crocidolite, tremolite, talc-anthophyllite, and other fibrous minerals. The average diameter, length, and length-to-diameter ratio of each type of fiber were also calculated. For total fibers > 5 microns, we found > 1,000 asbestos fibers per mg tissue (f/mg) in all cases; tremolite was above 1,000 f/mg in 8 cases, chrysotile in 6 cases, crocidolite in 4 cases, and talc anthophyllite in 5 cases. Among cases with asbestos fibers, the tremolite count was highest in 7 cases, chrysotile in 3 cases, and crocidolite in 2 cases. The geometric mean concentrations of fibers > or = 5 microns were in the following decreasing order: tremolite > crocidolite > chrysotile > other fibers > talc-anthophyllite > amosite. For total fibers < 5 microns, we found > 1,000 fibers per mg tissue (f/mg) in all cases; tremolite was above 1,000 f/mg in 12 cases, chrysotile in 8 cases, crocidolite in 7 cases, and talc-anthophyllite in 6 cases. Tremolite was highest in 8 cases, chrysotile in 2 cases, and crocidolite and amosite in 2 cases. The geometric mean concentrations of fibers < 5 microns were in the following decreasing order: tremolite > other fibers > chrysotile > crocidolite > talc-anthophyllite > amosite. We conclude, on the basis of the lung burden analyses of 12 mesothelioma cases from the Asbestos township of Quebec, that the imported amphibole (crocidolite and amosite) were the dominant fibers retained in the lung tissue in 2/12 cases. In 10/12 cases, fibers from the mine site (chrysotile and tremolite) were found at highest counts; tremolite was clearly the highest in 6, chrysotile in 2, and 2 cases had about the same counts for tremolite and chrysotile. If a relation of fiber burden-causality of mesothelioma is accepted, mesothelioma would be likely caused by amphibole contamination of the plant in 2/12 cases and by the mineral fibers (tremolite and chrysotile) from the mine site in the 10 other cases.

Topics: Aged; Asbestos; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestos, Serpentine; Culture Techniques; Humans; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Mining; Occupational Diseases; Quebec; Textile Industry

Tremolite is nearly ubiquitous and represents the most common amphibole fiber in the lungs of urbanites. Tremolite asbestos is not mined or used commercially but is a frequent contaminant of chrysotile asbestos, vermiculite, and talc. Therefore, individuals exposed to these materials or to end-products containing these materials may be exposed to tremolite. We have had the opportunity to do asbestos body counts and mineral fiber analysis on pulmonary tissue from five mesothelioma cases and two asbestosis cases with pulmonary tremolite burdens greater than background levels. There were no uncoated amosite or crocidolite fibers detected in any of these cases. Three patients were occupationally exposed to chrysotile asbestos; two patients had environmental exposures (one to vermiculite and one to chrysotile and talc) and one was a household contact of a shipyard worker. The tremolite burdens for the asbestosis cases were one to two orders of magnitude greater than those for the mesothelioma cases. Our study confirms the relationship between tremolite exposure and the development of asbestos-associated diseases. Furthermore, the finding of relatively modest elevations of tremolite content in some of our mesothelioma cases suggests that, at least for some susceptible individuals, moderate exposures to tremolite-contaminated dust can produce malignant pleural mesothelioma.

Topics: Adult; Aged; Asbestos; Asbestos, Amphibole; Asbestosis; Environmental Exposure; Female; Humans; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Occupational Exposure

Chrysotile formation arises through serpentinization of ultramafics and silicified dolomitic limestones. Rock types tend to control the trace metal content and both the nature and amounts of admixed minerals in the ore, such as fibrous brucite (nemalite) and tremolite. Some associated minerals and trace metals are thought to play a role in biological potential. Tremolite, one of the important associated minerals, may occur with different morphological forms, called habits. These habits range from asbestiform (tremolite asbestos) to common blocky or non-fibrous form (tremolite cleavage fragments). The latter is most common in nature. Tremolite in chrysotile ore varies in habit and concentration, both factors determining the degree of risk following inhalation. Tremolite fibre is thought to be important in relation to the occurrence of mesothelioma. Chrysotile fibrils may vary in diameter. Dust clouds generated following manipulation vary in fibre number and surface area. Chrysotile fibres exhibit a range of physical characteristics. The fibre may be non-flexible ('stiff') and low in tensile strength ('brittle'), and may lack an ability to curl. This fibre, referred to as 'harsh', sheds water more quickly than its curly, flexible 'soft' variety. The behaviour of the harsh fibres is more amphibole-like and their splintery nature suggests an enhanced inhalation potential. Slip fibre ore from Canada tends to contain more fibrous brucite (nemalite) than cross-fibre ore in the same mine. Industrial manipulation, which includes chemical treatment, heating and milling, may impart new surface properties to chrysotile dusts. Biological potential may be enhanced (opening of fibre bundles) or reduced (disruption of surface bonds and lessened ability to interact with organic moieties). Leaching of magnesium from chrysotile occurs at a pH less than about 10. Chrysotile has been demonstrated to lose magnesium in vivo and undergo clearance from the lung. The biological potential of magnesium-depleted chrysotile is much reduced, or even eliminated. Reduction of mesothelioma-inducing and cytotoxic potential has been observed and quantified experimentally. Use of chrysotile products in high-temperature environments may heat the mineral to the point where it undergoes alteration of properties, especially by dehydroxylation. Chrysotile ore may vary in properties and associated minerals: it may form aerosols with different size distributions, especially fibre/fibril diameters a

Topics: Asbestos, Amphibole; Asbestos, Serpentine; Asbestosis; Humans; Lung Neoplasms; Mesothelioma; Pleural Neoplasms; Research; Surface Properties; Trace Elements

Mesotheliomas are rare. While most are reported to be associated with exposure to durable fibres, a proportion are not caused by the inhalation of fibres at all. Reports of individual cases and studies of small groups are unreliable as evidence of cause because: (a) diagnosis is often unreliable; (b) even if chrysotile fibres are found in lung tissues, the mesothelioma may still be spontaneous. Present knowledge has not progressed much since 1964 when the absence of cases of mesothelioma in amosite and chrysotile miners in South Africa and the very low incidence in Canadian mines was known but not believed. Now we know this information was correct. The significance of low-level amphibole exposures in predominantly chrysotile mixes was not appreciated until studies of fibres in lungs using electron microscopy showed the high lung burden of amphibole fibres in the 1970s and 1980s. The effect of these findings is to make most European and U.S.A. factory cohorts inappropriate for the evaluation of chrysotile mesothelioma risk. Reviewing the current evidence published and unpublished, it seems likely that chrysotile uncontaminated by tremolite may not have caused any mesotheliomas even at high cumulative life-time exposures. Information on the mesothelioma risk among chrysotile user populations using fibres not containing tremolite is badly needed.

Topics: Animals; Asbestos, Amphibole; Asbestos, Serpentine; Humans; Industry; Mesothelioma; Mining; Occupational Exposure; Pleural Neoplasms; Risk Factors; Rodentia; Time Factors

Studies of human lungs indicate that, for virtually all types of exposure, the relative proportion of amphibole asbestos retained in the lung far exceeds the proportion in the original dust and, conversely, the relative proportion of chrysotile is far less than that in the original dust. Although amphiboles appear to accumulate in lung in proportion to exposure and chrysotile does not, failure of chrysotile deposition is probably not the reason for the disproportionate retention of amphibole fibres. The available data suggest that chrysotile is deposited in the parenchyma but is cleared extremely rapidly, with the vast bulk of fibres removed from human lungs within weeks to months after inhalation; by comparison, amphibole clearance half-lives are of the order of years to decades. The mechanisms of preferential chrysotile clearance remain uncertain, but fragmentation of chrysotile into short fibres, possibly accompanied by extremely rapid dissolution of such fibres, appears to be important in this process. Chrysotile fibres do penetrate to the periphery of the lung, so that differences in mesothelial pathogenicity of chrysotile and amphiboles in regard to mesothelioma are not caused by failure of chrysotile to reach the pleura. The theory that the tremolite contaminant rather than the chrysotile itself is the cause of 'chrysotile-induced' disease (especially mesothelioma) is consistent with the available human data, but the contrary ideas that disease is caused either by the total transient burden of inhaled chrysotile fibres or by a small, sequestered, long-retained fraction of chrysotile fibres still need to be excluded.

Topics: Animals; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestos, Serpentine; Asbestosis; Guinea Pigs; Humans; Lung; Mesothelioma; Mining; Occupational Exposure; Pleura; Pleural Neoplasms; Textile Industry; Time Factors

Topics: Asbestos; Asbestos, Amosite; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestos, Serpentine; Asbestosis; Humans; Mesothelioma; Pleural Neoplasms; Risk Factors

We describe a case of malignant peritoneal mesothelioma arising in a 17-year-old boy. The diagnosis was based on a comprehensive study including light microscopy, histochemistry, immunohistochemistry, evaluation of the clinical course, and autopsy examination. Analytical transmission electron microscopy showed a concentration of 510,000 asbestos fibers/g dry lung tissue. The fibers were represented by chrysotile (62%) and tremolite (38%) asbestos. About 40% of the total fibers were longer than 5 microns. The presence of tremolite fibers was probably due to environmental exposure to contaminated cosmetic talc. This is the first reported case of pathologically proven exposure to asbestos dust in malignant mesothelioma of childhood and adolescence.

Topics: Adolescent; Asbestos, Amphibole; Asbestos, Serpentine; Autopsy; Humans; Male; Mesothelioma; Peritoneal Neoplasms

Since 1980, we have collected fourteen cases of mesothelioma induced by environmental exposure to asbestos, going back to childhood in patients from north-east Corsica, in a region which was remote from the asbestos mine of Canari. There were eight men and six women with a mean age of 69.5 +/- 4 years. Six patients presented with bilateral calcified pleural plaques as evidence of environmental exposure. The mineral analysis carried out on five patients (four had thoracoscopies and one an alveolar lavage), showed a moderate deposit of chrysotile (0.3 to 3.4 x 10(6) fibres per gram of dry tissue), and elevated level of tremolite (1.4 to 62 x 10(6) fibres/g). The ambient dosage of asbestos has confirmed the existence of environmental pollution by chrysotile fibres and above all by tremolite. In addition, the same type of fibres have been identified in the parietal pleural of animals subjected to the same risk. In this region, the risk is estimated, on the basis of our results, as 10 cases of mesothelioma per 100,000 inhabitants per year.

Topics: Adult; Aged; Aged, 80 and over; Air Pollutants; Animals; Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Bronchoalveolar Lavage Fluid; Dog Diseases; Dogs; Environmental Exposure; Female; France; Goat Diseases; Goats; Humans; Incidence; Male; Mesothelioma; Middle Aged; Mining; Occupations; Pleural Neoplasms; Population Surveillance; Retrospective Studies; Risk Factors; Survival Rate; Thoracoscopy

To examine how fiber type, fiber concentration, and fiber size correlate with the presence of asbestos-related disease in workers with heavy chrysotile exposure, we used analytic electron microscopy to determine the fiber content of the lungs of 94 long-term chrysotile miners and millers from the region of Thetford Mines, Quebec. Mesothelioma, airway fibrosis, and asbestosis were strongly associated with a high tremolite fiber concentration, whereas pleural plaques and carcinoma of the lung showed no relationship to tremolite burden. Similar patterns were seen for chrysotile concentration, but further analysis suggested that the apparent effect of chrysotile probably was due to the high correlation (r = 0.70) between chrysotile and tremolite concentration rather than to an independent effect of chrysotile. Increased tremolite-chrysotile ratio was marginally associated with the presence of pleural plaques but not with any other disease. Very high correlations (r > 0.90) between the concentrations of fibers longer or shorter than 8 microns prevented assessment of the effects of long compared with short fibers. Pleural plaques were very strongly associated with higher mean tremolite fiber aspect ratios, but no differences in mean fiber size (length, width, aspect ratio, surface area, and mass) were seen for any other disease. Total fiber size measures (total fiber length/g and others) showed differences similar to fiber concentration for mesothelioma, airways fibrosis, and asbestosis, but no one measure was clearly better than another or better than fiber concentration. We conclude that, in this population of heavily exposed chrysotile miners and millers, the presence of airways fibrosis and asbestosis and, probably, mesothelioma reflects high tremolite burden.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Aged; Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Asbestosis; Humans; Lung; Lung Neoplasms; Mesothelioma; Microscopy, Electron; Middle Aged; Mining; Particle Size; Pleural Diseases; Pulmonary Fibrosis; Quebec; Regression Analysis; Silicic Acid

Malignant pleural mesothelioma in rural Turkey frequently results from environmental exposure to tremolite asbestos or fibrous zeolite (erionite). The aim of this study was to determine the CT features of malignant pleural mesothelioma in patients exposed to asbestos or erionite.. The CT scans of 84 patients with proved malignant pleural mesothelioma were retrospectively evaluated. Twenty patients (24%) had been exposed to erionite and 64 patients (76%) had been exposed to asbestos. The CT scans were interpreted by seven observers who did not know the clinical or pathologic findings.. CT scans showed either unilateral pleural thickening or pleural nodules/masses in all patients. Pleural nodules were present in 25 patients (30%) and pleural masses in 44 patients (52%). Pleural effusion was found in 61 patients (73%), mediastinal pleural involvement in 78 (93%), pleural calcifications in 52 (62%), involvement of the interlobar fissures in 64 (76%), and volume contraction in 61 (73%). Reduced size of the hemithorax was significantly correlated with chest wall involvement. On the basis of CT findings, the preassigned staging was changed in 21 patients (25%), including 44% of the patients with disease that had been classified as stage I. CT findings were not significantly different between the patients exposed to erionite and those exposed to asbestos.. The most common CT findings in cases of malignant pleural mesothelioma were unilateral pleural thickening or pleural nodules/masses with or without effusion. CT provided valuable information on the extent of the disease, which was important for staging. Although the CT features are not pathognomonic, they provide valuable clues to the diagnosis in patients who have been exposed to mineral fibers.

Topics: Adult; Aged; Aluminum Silicates; Asbestos; Asbestos, Amphibole; Environmental Exposure; Female; Humans; Male; Mesothelioma; Middle Aged; Pleura; Pleural Neoplasms; Radiography, Thoracic; Retrospective Studies; Silicic Acid; Tomography, X-Ray Computed; Turkey; Zeolites

Samples of Metsovo-tremolite asbestos, previously found to be the causative agent of endemic pleural calcification and an increased level of malignant pleural mesothelioma in a rural area of north-western Greece (Metsovo area), were tested in various in vitro toxicity test systems. It was found that asbestos fibres of this type were strong inducers of micronuclei and numerical chromosomal abnormalities while they induced low levels of chromosomal aberrations in mammalian cells in culture. Furthermore, this type of asbestos can induce a low level of in vitro transformation of Syrian hamster embryo cells. The fibres had no effect on gap-junctional cell-cell communication (followed by the dye-transfer method) and did not induce any mutations in the Salmonella typhimurium strain TA102 which is known to be sensitive to the action of various oxidative agents. These results support the hypothesis generated from studies on other types of asbestos that such fibres induce tumours by causing chromosomal mutations.

Topics: Aneuploidy; Animals; Asbestos; Asbestos, Amphibole; Cell Communication; Cell Line; Cell Transformation, Neoplastic; Chromosome Aberrations; Cricetinae; Cricetulus; Greece; Humans; Incidence; Mesocricetus; Mesothelioma; Micronucleus Tests; Mutagenesis; Mutagenicity Tests; Pleural Neoplasms; Salmonella typhimurium; Silicic Acid

Six samples of tremolite of different morphological type were prepared as dusts of respirable size and used in intraperitoneal injection studies in rats. Three "asbestiform" tremolites produced mesotheliomas in almost all animals, although with significantly different tumor-induction periods. A brittle type of fibrous tremolite which, when manipulated to prepare "respirable dust," produced a sample with relatively few asbestiform fibers remaining nonetheless produced tumors in 70% of rats. Two samples of nonfibrous tremolite produced respirable dust samples containing numerous elongated fragments with aspect ratios greater than 3:1, which therefore fitted the definition of respirable fibers. Both these samples produced relatively few tumors, although one had more long "fibers" than did the brittle tremolite that produced 70% of tumors. This study has therefore demonstrated that different morphologic forms of tremolite produce dusts with very different carcinogenic potential. Carcinogenicity does not depend simply on the number of elongated particles injected, and we need to develop methods of distinguishing carcinogenic tremolite fibers from relatively innocuous tremolite dusts, with similar numbers of elongated particles of similar aspect ratios.

Topics: Animals; Asbestos, Amphibole; Carcinogens; Dust; Injections, Intraperitoneal; Mesothelioma; Particle Size; Peritoneal Neoplasms; Rats; Silicic Acid

Endemic PCs and high incidence of malignant mesothelioma from household use of asbestos have been reported in Metsovo in northwestern Greece ("Metsovo lung"). In the present study, we present similar findings in six more areas of Greece. Like Metsovo, all these areas are located within ophiolite belts. Like Metsovo, material similar to "Metsovo whitewash" has been used for various domestic uses. Asbestos fibers (chrysotile, antigorite and tremolite) were found in three of the six areas. Also, in two, MPM has been diagnosed. These findings suggest that "Metsovo lung" occurs in several areas of Greece and has similar etiology and epidemiology.

Topics: Aged; Asbestos; Asbestos, Amphibole; Asbestosis; Calcinosis; Environmental Exposure; Greece; Humans; Incidence; Mesothelioma; Middle Aged; Pleural Diseases; Pleural Neoplasms; Silicic Acid; Soil

Lung tissue from 76 deceased asbestos cement workers (seven with mesothelioma) exposed to chrysotile asbestos and small amounts of amphiboles, has been studied by transmission electron microscopy, together with lung tissue from 96 controls. The exposed workers with mesothelioma had a significantly higher total content of asbestos fibre in the lungs than those without mesothelioma, who in turn, had higher concentrations than the controls (medians 189, 50, and 29 x 10(6) fibres/g (f/g]. Chrysotile was the major type of fibre. The differences were most pronounced for the amphibole fibres (62, 4.7, and 0.15 f/g), especially crocidolite (54, 1.8 and less than 0.001 f/g), but were evident also for tremolite (2.9, less than 0.001, and less than 0.001 f/g) and anthophyllite (1.7, less than 0.001, and less than 0.001 f/g). For amosite, there was no statistically significant difference between lungs from workers with and without mesothelioma; the lungs of workers had, however, higher concentrations than the controls. Strong correlations were found between duration of exposure and content of amphibole fibres in the lungs. Asbestos bodies, counted by light microscopy, were significantly correlated with the amphibole but not with the chrysotile contents. Fibrosis was correlated with the tremolite but not the chrysotile content in lungs from both exposed workers and controls. Overall, similar results were obtained using fibre counts and estimates of mass.

Topics: Adult; Aged; Aged, 80 and over; Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Construction Materials; Humans; Lung; Mesothelioma; Middle Aged; Occupational Diseases; Pulmonary Fibrosis; Silicic Acid; Silicon Dioxide

For many years, the main source of asbestos in Cyprus was thought to be the chrysotile mine in the central mountains. When a woman, who had no connection with the mine, developed mesothelioma, it was surprising to discover tremolite asbestos bodies within her lung. However, further studies have shown that tremolite occurs as a contaminant within the chrysotile ore body. In this study we have shown that both chrysotile and tremolite can be found in domestic and environmental samples throughout the mountain region; in particular, numerous fine fibres of both materials are present in stucco. Preliminary radiological studies have shown pleural disease in the village population and 5 out of 13 known cases of mesothelioma have arisen in persons unconnected with the mine. This suggests an environmental contribution to asbestos-related disease on the island.

Topics: Air Pollutants; Animals; Asbestos; Asbestos, Amphibole; Asbestos, Crocidolite; Asbestos, Serpentine; Cyprus; Humans; Lung; Mesothelioma; Mining; Pleural Neoplasms; Radiography; Sheep; Silicic Acid

Topics: Asbestos, Amphibole; Calcinosis; Greece; Humans; Mesothelioma; Paint; Pleural Diseases; Silicic Acid; Silicon Dioxide

A small cohort of 194 men with low exposure to fibrous tremolite (mean 0.75 f/ml y) in the mining and milling of vermiculite in South Carolina experienced 51 deaths 15 years or more from first employment. The SMR (all causes) was 1.17 reflecting excess deaths from circulatory disease. There were four deaths from lung cancer and 3.31 expected (SMR 1.21, 95% CI 0.33-3.09). Three of the four deaths were in the lowest exposure category (less than 1 f/ml y); no death was attributed to mesothelioma or pneumoconiosis. These findings contrast with those in Montana where the vermiculite ore was heavily contaminated with fibrous tremolite. A radiographic survey of 86 current and recent South Carolina employees found four with small parenchymal opacities (greater than or equal to 1/0) and seven with pleural thickening. These proportions were not higher than in a non-exposed group and much lower than had been observed in Montana. Examination of sputum from 76 current employees showed that only two specimens contained typical ferruginous bodies, confirming low cumulative fibre exposure. Any possible adverse effects of work with vermiculite, minimally contaminated with fibrous or non-fibrous tremolite, were thus beyond the limits of detection in this workforce.

Topics: Aluminum Silicates; Asbestos, Amphibole; Canada; Cohort Studies; Humans; Lung Neoplasms; Mesothelioma; Mining; Occupational Diseases; Pulmonary Fibrosis; Silicic Acid; Silicon Dioxide

Topics: Asbestos, Amphibole; Asbestosis; Humans; Mesothelioma; Pleural Neoplasms; Risk Factors; Silicic Acid; Silicon Dioxide

Topics: Adult; Asbestos; Asbestos, Amphibole; Environmental Exposure; Female; Humans; Lung Diseases; Male; Mesothelioma; Pleural Diseases; Pleural Neoplasms; Rural Population; Silicic Acid; Silicon Dioxide; Turkey

Topics: Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Humans; Lung Neoplasms; Mesothelioma; Occupational Diseases; Silicic Acid

Topics: Adult; Asbestos; Asbestos, Amphibole; Asbestosis; Environmental Exposure; Female; Hodgkin Disease; Humans; Male; Mesothelioma; Middle Aged; Pleural Neoplasms; Rural Population; Silicic Acid; Stomach Neoplasms; Turkey

There is a chrysotile mine in the central mountains of Cyprus but no other appreciable source of industrial asbestos. Hence the island was thought to offer ideal conditions to seek pure chrysotile induced mesothelioma. The first reported case was a village woman whose lung tissue contained amphibole asbestos fibres, which were later identified as tremolite. This began a search for the origin of her exposure to asbestos. Our studies have shown that tremolite is widespread, being found, along with chrysotile, in domestic and environmental dust samples. Other cases of mesothelioma have been diagnosed, and the pattern of their distribution suggests that the mine is not the major source of disease. Exposure to tremolite is equally, if not more, important.

Topics: Aged; Asbestos, Amphibole; Cyprus; Dust; Female; Humans; Lung; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Silicic Acid; Silicon Dioxide

Pleural thickening, bilateral pleural hyalinised plaques, and restrictive lung function are found among inhabitants of four small villages in northwestern Greece. Transbronchial biopsy samples from patients with disease contained tremolite fibres. Malignant pleural mesothelioma has now been reported in these villages and accounts for approximately 1% of the total mortality from 1981 to 1985. The principal whitewash once used in this area is predominantly asbestiform tremolite. The fibre is identical in every respect to fibres found in the lung tissues of people with Metsovo lung. The membrane activity of this tremolite is greater than that of the commercially used asbestiform amphiboles amosite and crocidolite. This measure of cytotoxicity lends further support to the hypothesis that this fibre is the agent of Metsovo lung and mesothelioma.

Topics: Adult; Aged; Asbestos, Amphibole; Calcinosis; Environmental Exposure; Female; Greece; Humans; Lung Diseases; Male; Mesothelioma; Middle Aged; Paint; Pleural Neoplasms; Silicic Acid; Silicon Dioxide; X-Ray Diffraction

The vermiculite ore and concentrate of a mine and mill located near Libby, Montana was found to be contaminated with a fiber of the tremolite/acetinolite series. A study was conducted to estimate the exposure-response relationship for mortality for 575 men who had been hired prior to 1970 and employed at least 1 year at the Montana site. Individual cumulative fiber exposure (fiber-years) was calculated. Results indicated that mortality from nonmalignant respiratory disease (NMRD) and lung cancer was significantly increased compared to the U.S. white male population. For those workers more than 20 years since hire, the standard mortality rate (SMR) for lung cancer (ICDA 162-163) was 84.7, 225.1, 109.3, and 671.3 for less than 50, 50-99, 100-399, and more than 399 fiber-years respectively. Corresponding results for NMRD (ICDA 460-519) were 327.8, 283.5, 0, and 278.4. Based on a linear model for greater than 20 years since hire, the estimated percentage increase in lung cancer mortality risk was 0.6% for each fiber-year of exposure. At 5 fiber-years, the estimated percentage was 2.9% from an unrestricted (nonthreshold) linear model and 0.6% from a survival model.

Topics: Aluminum Silicates; Asbestos, Amphibole; Humans; Lung Neoplasms; Male; Mesothelioma; Minerals; Mining; Montana; Occupational Diseases; Silicon Dioxide; Smoking; Time Factors

Topics: Aluminum Silicates; Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Environmental Exposure; Female; Humans; Male; Mesothelioma; Middle Aged; Minerals; Occupational Diseases; Peritoneal Neoplasms; Pleural Neoplasms; Time Factors; Zeolites

A 41-year-old man was found to have a malignant mesothelioma of the pleura. During childhood in Corsica, he had been exposed at home to chrysotile ore from the Canari mine. Analysis of lung mineral content revealed background levels of chrysotile but an elevated level of tremolite and actinolite asbestos. The latter had a geometric mean length of 3.7 microns, a value considerably longer than we have found for tremolite and actinolite from Quebec chrysotile miners but roughly the same as the mean length of amosite and crocidolite in workers with occupational amphibole exposure. No tremolite or actinolite fibers of length greater than 8 microns microns and width less than 0.25 micron were observed. The mean aspect ratio of the tremolite and actinolite fibers was 7, a value similar to that found in chrysotile miners with mesothelioma but considerably less than the mean aspect ratio of amosite and crocidolite from those with occupational exposure. These data suggest that long-fiber tremolite is a potential mesothelial carcinogen in humans, and that fiber length is more important than fiber aspect ratio in this regard.

Topics: Adult; Asbestos, Amphibole; Biopsy; Humans; Male; Mesothelioma; Microscopy, Electron; Pleura; Pleural Neoplasms; Silicic Acid; Silicon Dioxide

The role of chrysotile asbestos in the genesis of mesotheliomas in humans is disputed. We analyzed the asbestos content of the lung in 6 long-term chrysotile miners and millers who had pleural mesotheliomas. In five patients, only chrysotile ore components (chrysotile and tremolite/actinolite/anthophyllite types of amphibole asbestos) were found, while the sixth patient presented both chrysotile ore components and amosite, a type of asbestos that is not derived from the mining process. The mean number of fibers/g dry lung for the 5 patients with mesothelioma containing only chrysotile ore components was higher (chrysotile 64 X 10(6) and tremolite group 540 X 10(6] than in a group of long-term chrysotile miner control subjects who had no asbestos-related disease (chrysotile 23 X 10(6), tremolite group 58 X 10(6], but some patients with mesothelioma had fiber burdens near the mean of the control range. Fiber sizes and aspect ratios in the mesothelioma group were approximately the same as those in the control subjects, and analysis of fiber distribution failed to show any preferential localization in the periphery of the lung. However, the concentration ratio of tremolite in the lungs of the mesothelioma cases compared to the control cases was 9.3, while the ratio of chrysotile was only 2.8. Our findings provide strong evidence that chrysotile mine dust (chrysotile and amphibole components) can produce mesotheliomas in humans; the greater relative amounts of tremolite group amphiboles present in the patients with mesothelioma raise the possibility that these fibers may be important in the pathogenesis of the tumors.

Topics: Aged; Asbestos; Asbestos, Amphibole; Asbestos, Serpentine; Humans; Lung; Lung Neoplasms; Male; Mesothelioma; Middle Aged; Minerals; Occupational Diseases

Tremolite is an amphibole which has been implicated in a variety of disease patterns in different parts of the world. It occurs in a number of phases, which are chemically identical but have specific physical characteristics. In an attempt to clarify the epidemiological findings, tremolite fibres of 3 specific forms--A, B and C--were characterized and studied for biological activity by: (i) in vivo intrapleural injection of rats (2 separate experiments--1 with poor survival). (ii) in vitro enzyme release from mouse peritoneal macrophages (iii) in vitro giant-cell formation in A549 cultures (iv) in vitro cytotoxicity for V79-4 cells. Sample C, which contained more long thin fibres than A and B, was alone in producing mesotheliomas. C, but not A or B, induced LDH and B-glucuronidase enzyme release, and induced giant cells. A was not cytotoxic, B moderately cytotoxic and C as highly cytotoxic as UICC crocidolite. The in vivo studies were marred by being split between 2 experiments, of which the second had poor survival. We are aware of the weakness of our in vivo data, but as Tremolite C was being considered for commercial use on the European market we felt it timely to submit our findings for publication.

Topics: Animals; Asbestos, Amphibole; Cell Line; Cricetinae; Cricetulus; Dust; Female; Humans; Lung Neoplasms; Macrophages; Male; Mesothelioma; Mice; Mutagenicity Tests; Neoplasms, Experimental; Particle Size; Rats; Rats, Inbred Strains; Silicic Acid; Silicon Dioxide