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PubMed1993

[Comparative evaluation of dust oncogenicity in asbestos-containing and non-asbestos details].

Experiments proved higher carcinogenicity of chrisotyle-asbestos than of dust appearing in mechanical processing of asbestos-containing details and in wearing articulated shoe brakes. Substitution of asbestos for basalt fibers leaves oncologic risk intact among workers engaged into mechanical processing of asbestos-containing brakes. Avoiding asbestos in mixtures for brakes could lower risk. Results support conclusions obtained by cohort studies in Yaroslavl.

Animals↗

PubMed1990

Mineral fibres, fibrosis, and asbestos bodies in lung tissue from deceased asbestos cement workers.

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.

Adult↗

PubMed1990

Asbestos bodies in bronchoalveolar lavage fluids of brake lining and asbestos cement workers.

Asbestos body (AB) concentrations in bronchoalveolar lavage samples of 15 brake lining (BL) workers exposed only to chrysotile have been determined and compared with those from 44 asbestos cement (AC) workers extensively exposed to amphiboles. The mean AB concentrations (263 +/- 802 and 842 +/- 2086 AB/ml respectively) for those groups did not differ significantly but were much higher than those found in control groups. Analytical electron microscopy of asbestos body cores showed that in the BL group 95.6% were chrysotile fibres whereas in the AC group amphiboles accounted for 93.1%. The size characteristics of the central fibres differed for chrysotile and amphibole AB, the former being shorter and thinner. Examination of repeated bronchoalveolar lavage samples showed that the mechanisms of clearance of chrysotile fibres do not affect AB concentration for at least 10 months after cessation of exposure. It thus appears that routine counting of ABs in BAL allows the assessment of current or recent occupational exposures to asbestos. Exposures to chrysotile lead to AB concentrations comparable with those encountered in exposures to amphiboles.

Asbestos↗

PubMed1997

Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers.

In recent years, controversy has developed about whether pre-existing asbestosis is a prerequisite for the diagnosis of asbestos-related lung cancer. This paper presents the results of a prospective study, in a cohort of Ontario asbestos-cement workers, of lung cancer in relation to radiographs obtained 20 and 25 years from first exposure to asbestos. Radiographs were interpreted by a single NIOSH-certified "B" reader, and asbestosis was defined to mean an ILO code of 1/0 or greater. There were 143 subjects (123 without asbestosis, 20 with asbestosis), with a radiograph available for interpretation at 20 years from first exposure or later. The lung cancer standardized mortality ratio (SMR) among men without asbestosis at 20 years latency was 5.53 (95% CI: 2.9-9.7). There were 128 subjects (114 without asbestosis, 14 with asbestosis) with a radiograph available for interpretation at 25 years from first exposure or later. The lung cancer SMR among men without asbestosis at 25 years latency was 5.81 (95% CI 2.7-11). The results of this study are consistent with those of epidemiologic studies of asbestos-exposed populations in a variety of exposure situations. These studies have demonstrated that lung cancer risk is elevated in the presence of radiographic asbestosis, but they have also shown that lung cancer risk may be elevated in the absence of radiographic asbestosis.

Asbestos↗

PubMed1994

Differential role of hydrogen peroxide and organic peroxides in augmenting asbestos-mediated DNA damage: implications for asbestos induced carcinogenesis.

The incubation of asbestos with DNA in presence of peroxides augmented DNA damage several fold as compared to the damage caused by individual treatments. Asbestos in presence of hydrogen peroxide causes DNA double strand breaks, damage to its deoxyribose sugar moiety and enhanced DNA fidelity. However, only DNA double strand breaks and enhanced DNA fidelity could be recorded in presence of organic hydroperoxide/peroxide but no DNA sugar damage could be observed. Further, the extent of DNA damage could be correlated to the carcinogenic potential of asbestos fibre. Crocidolite, the most carcinogenic variety of asbestos, produces maximum damage to DNA in presence of both hydrogen peroxide and organic hydroperoxide/peroxide while chrysolite which is only a co-carcinogen produces significantly less DNA damage. The observed differences in DNA damage by hydrogen peroxide and organic hydroperoxide/peroxide have been ascribed to the differential reactivity of DNA with hydroxyl and alkoxy/aryloxy free radicals produced respectively from these inorganic and organic peroxides.

Animals↗

PubMed2002

[Findings in a high-risk group following asbestos exposure. Benefit of ENT examinations in patients with long-term exposure to asbestos].

BACKGROUND AND OBJECTIVE: Laryngeal diseases caused by exposure to asbestos are listed in the current German list of occupational diseases under number 4104. Parallel to a multicenter study to evaluate whether a CT scan should be included in the examinations for occupational diseases according to the German surveillance guidelines, an additional ENT examination was evaluated. PATIENTS AND METHODS: One hundred workers with a mean exposure time to asbestos of 20.9 years were given a complete ENT examination in 4 consecutive years (1993-1996). Radiological signs for asbestosis were observed in 21 cases and 58 participants had pleural affections caused by asbestos. Significant nicotine abuse was reported by 15 persons: 61 participants were ex-smokers and 24 had never smoked. Regular alcohol consumption was reported by 90% (11% more than 80 g/day). RESULTS: As documented in the literature, we found a high prevalence of laryngitis, especially in smoking patients. One patient had early laryngeal cancer (T1). CONCLUSION: The integration of an ENT examination into the German surveillance guidelines for occupational diseases should be discussed for patients with a high exposure to asbestos.

Aged↗

PubMed1975

Technological feasibility of the 2 fibers/cc asbestos standard in asbestos textile facilities.

The technical feasibility of developing dust control practice which would bring the asbestos industry into compliance with the OSHA I fibers/cc standard, scheduled to become effective July 1, 1976, has been questioned since its promulgation. This paper presents the results of industrial hygiene surveys, including the results of 243 asbestos air samples, conducted at two asbestos textile production facilities which have achieved the 2 fibers/cc standard. Both facilities use nonconventional production techniques. Conclusions drawn from the investigations express the need for: (1) a study of new products; (2) a tool to motivate consumers to switch to the new products when appropriate; and (3) legislation which will protect all domestic producers of asbestos textiles from certain producers who do not have to absorb the added expense of meeting the OSHA standard.

Air Pollution↗

PubMed1996

Retention of asbestos fibres in lungs of workers with asbestosis, asbestosis and lung cancer, and mesothelioma in Asbestos township.

OBJECTIVE: To conduct a mineralogical study on the particles retained in the necropsied lungs of a homogenous group of asbestos miners and millers from Asbestos township (and a local reference population) and to consider the hypothesis that there is a difference in size between fibres retained in the lungs of patients with asbestosis with and without lung cancer. METHODS: Samples of lung tissue were obtained from 38 patients with asbestosis without lung cancer, 25 with asbestosis and lung cancer, and 12 with mesothelioma, from necropsied Quebec chrysotile miners and millers from Asbestos township. Fibre concentrations in the lungs of these patients were compared with those in tissue from necropsies carried out on a local reference population: men who had died of either accidental death or acute myocardial infarction between 1990 and 1992. 23 were born before 1940 and 26 after 1940. RESULTS: Geometric mean (GM) concentrations were higher in cases than in the controls for chrysotile fibres 5 to 10 microns long in patients with asbestosis with or without lung cancer; for tremolite fibres 5 to 10 microns long in all patients; for crocidolite, talc, or anthophyllite fibres 5 to 10 microns long in patients with mesothelioma; for chrysotile and tremolite fibres > or = 10 microns long in patients with asbestosis; and crocidolite, talc, or anthophyllite fibres > or = 10 microns long in patients with mesothelioma. However, median concentrations of each type of fibre in the lungs did not show any significant differences between the three disease groups. Average length to diameter ratios of the fibres were calculated to be larger in patients with asbestosis and lung cancer than in those without lung cancer for crocidolite fibres > or = 10 microns long, for chrysotile, amosite, and tremolite fibres 5 to 10 microns long, and for chrysotile and crocidolite fibres < 5 microns long. However, there was no statistical difference in the median length to diameter ratios for any type of fibres across the disease groups when they were calculated in each patient. Cumulative smoking index (pack-years) was higher in the group with asbestosis and lung cancer but was not statistically different from the two other disease groups. CONCLUSION: Lung cancers occurred in workers with asbestosis from Asbestos township who had an equal concentration of retained fibres but a tendency to a higher length to diameter ratio of amphiboles. These workers had a 29% higher average cumulative smoking index.

Adult↗

PubMed1980

Comparison of sputum and lung asbestos body counts in former asbestos workers.

The asbestos (ferruginous) body content of lung tissues was compared to the number of asbestos bodies (AB) in sputum from 6 former amosite asbestos workers. Lung tissue was obtained at autopsy (5 subjects) and lobectomy (1 subject), and AB content was determined by a digestion-concentration technique. The sputum obtained was collected by both spontaneous cough (a pooled, 3-day specimen) and aerosolized hypertonic saline induction. Four slides treated with Papanicolaou's stain were prepared from each cytologic specimen and scored from 0 to 3 + on the basis of the total number of AB counted on the 4 slides. A significant correlation (P < 0.02) was found between the number of AB per gram of lung tissue and the percentage of sputum specimens from each worker than were positive for AB. Asbestos bodies were identified in 46% of sputum specimens from the 4 workers whose lungs contained 900 or more AB/g of lung tissue.

Aged↗

PubMed1983

Asbestos fiber content of the lungs in patients with and without asbestos airways disease.

I analyzed the total pulmonary asbestos burden in the lungs of 9 chrysotile miners who had asbestos airways disease (so-called "early asbestosis") but no evidence of classic asbestosis (interstitial fibrosis) on pathologic examination. The results were compared with values found for 9 miners matched for age, sex, smoking, and work length who had no histologic evidence of asbestosis or asbestos airways disease. The mean value for chrysotile fibers in the airway disease group was 47 X 10(6)/g dried lung, compared with 23 X 10(6) in the group without lesions (p less than 0.04). For contaminant amphiboles, probably derived from the chrysotile ore (tremolite, actinolite, anthophyllite), the corresponding values were 106 X 10(6) versus 58 X 10(6) (p less than 0.06), and for total asbestos fibers, 153 X 10(6) versus 81 X 10(6) (p less than 0.06). There was a strong correlation between amount of chrysotile and amphibole for each case, suggesting that the amphibole was probably a good measure of the original (but no longer present) chrysotile burden. No differences were seen between the 2 groups with regard to fiber size distribution, aspect ratios, or fiber widths. I conclude that the overall differences in fiber concentration between the 2 groups, although significant, are sufficiently small enough to suggest that other factors may be involved in the genesis of small airway lesions.

Aged↗

PubMedDate not supplied

The diagnosis and attribution of asbestos-related diseases in an Australian context: report of the Adelaide Workshop on Asbestos-Related Diseases. October 6-7, 2000.

Predictions of future cases of mesothelioma in Australia to the year 2020 are in the order of a total of 10,000 new cases. Compensation claims are testing the attribution in a particular case between occupational asbestos exposure and lung cancer. The cost of the problem necessitates clarifying and standardizing the criteria for a confident diagnosis of asbestos-related disease. The possibility of differences in criteria that determine attribution of asbestos to a disease prompted a consensus meeting of pathologists, epidemiologists, physicians, oncologists, radiologists, and others to define current thinking and to agree on an Australian document based on the scientific evidence for establishing diagnoses and attribution data of asbestos-related diseases in Australia. The participants' findings are reported.

Asbestos↗

PubMed2004

Double standards: the multinational asbestos industry and asbestos-related disease in South Africa.

This study documents and contrasts the development of knowledge about asbestos-related disease (ARD) in South Africa and the United Kingdom. It also contributes to the globalization debate by exploring corporate decision-making in a multinational industry. Between the 1930s and 1960s, the leading U.K. asbestos companies developed a sophisticated knowledge of ARD, though in South Africa, where the leading companies such as Turner & Newall and Cape Asbestos owned mines, there was little attempt to apply this knowledge. Asbestos mines (and their environments) in South Africa were uniquely dusty and ARD was rife. Social and political factors in South Africa, especially apartheid, allowed these companies to apply double standards, even after 1960 when the much more serious hazard of mesothelioma was identified. This shows the need for greater regulation of multinationals. Because of the lack of such regulation in the early 1960s, an opportunity was lost to prevent the current high morbidity and mortality of ARD both in South Africa and worldwide.

Asbestos↗

PubMed2001

An operated case of lung cancer with pleural plaques: its asbestos bodies, fiber analysis and asbestos exposure.

This case was a 79-year-old man with pleural plaques, which had been pointed out in the left lung field on chest X-ray six years ago. A new shadow in the right chest appeared in 1999 and was closely examined. Cytological class IV carcinoma was detected in his lung tissue obtained by broncho-fiberscope. Lobectomy of the right upper lobe was performed, and calcified pleural plaques were found on the chest wall. The clinical diagnosis was poorly differentiated squamous cell carcinoma, T1N0M0. In World War II when he was 26 years old, he had worked as a boiler man on a battle cruiser for one year. The amount of asbestos bodies (AB) was 3,348 per gram dry lung tissue. The cores of AB and asbestos fibers were examined and showed that amosite was the most prevalent and crocidolite, tremolite and chrysotile were present in that order. After leaving the navy, he had worked as a farmer throughout his life, suggesting that he had never contacted asbestos occupationally after being a boiler man. It is strongly suggested that he had been exposed to asbestos during his work as a boiler man and that produced pleural plaques and lung cancer 50 years' later.

Aged↗

PubMed2006

Redox status and expression of chemokines in the rat lungs on exposure to asbestos and asbestos substituents.

OBJECTIVES: Activity of cytoplasmatic superoxide dismutase, glutathione peroxidase,- and reductase, gamma-glutamyl transpeptidase and expression of macrophage chemoattractant protein-1 and macrophage inhibitory protein-1alpha was determined in primary culture of rat alveolar macrophages and type II pneumocytes after exposure to stone-wool, wollastonite and crocidolite (blue asbestos). METHODS: The activity of redox enzymes was examined by RANDOX kits, chemokines were studied by ELISA. RESULTS: The UICC crocidolite (positive control) decreased the activity of all redox enzymes and increased the expression of chemokines, whereas the two asbestos substituents did not alter the activity of redox enzymes either in the alveolar macrophages or pneumocytes. Stone-wool and wollastonite moderately increased the expression of chemokines in both cells. CONCLUSIONS: The redox status and production of chemokines changed in the opposite direction, presumably owing to stronger toxic effect of asbestos. These data suggest that stone-wool and wollastonite, as potential substituents for asbestos, are less toxic than the human carcinogenic and fibrogenic crocidolite.

Animals↗

PubMed1989

Possible generation of hydrogen peroxide and lipid peroxidation of erythrocyte membrane by asbestos: cytotoxic mechanism of asbestos.

We studied a mechanism of hemolysis induced by asbestos particles or silicic acid. This hemolysis was instantly initiated by mixing red blood cells with asbestos particles or silicic acid, and reached a plateau within 10 min. The hemolysis was suppressed by catalase, radical quenchers, deoxygenation, or phospholipids. The degree of the hemolysis was proportional to either the amount of asbestos added into red blood cell suspension or the amount of thiobarbituric acid-reacting substances formed. These findings suggest that in vitro hemolysis induced by asbestos particles (or silicic acid) is ascribed to membrane lipid peroxidation initiated by hydrogen peroxide which was generated by the interaction of the mineral particles with biological membranes.

Asbestos↗

PubMedDate not supplied

Mesotheliomas and asbestos type in asbestos textile workers: a study of lung contents.

The asbestos contents of the lungs of former employees of an asbestos textile factory were determined at necropsy using a transmission electron microscope. Those who had died of mesothelioma were compared with a matched sample of those who had died of other causes. The predominant fibre processed in the factory was chrysotile, but crocidolite had also been used. The lung content was consistent with the known exposure to chrysotile, but the crocidolite content was also high, being about 300 times that of the general population of the United Kingdom. The lungs of those with mesothelioma did not contain more of either chrysotile or crocidolite than the lungs of the controls, so no particular type of asbestos could be implicated in causing the mesotheliomas. The evidence of substantial exposure to crocidolite means that the mesotheliomas that occurred in this factory could not be attributed with any certainty to the exposure to chrysotile.

Aged↗

PubMed1990

Individual asbestos exposure: smoking and mortality--a cohort study in the asbestos cement industry.

A historical prospective cohort study comprised all persons employed from 1950 to 1981 for at least three years in the oldest asbestos cement factory in the world. From 2816 persons eligible for the study, record based estimates and measurements of dust and fibres and histories of smoking based on interviews were used to calculate individual exposures over time. After observation of 51,218 person-years and registration of 540 deaths, underlying causes of death for this cohort were compared with those for the regional population on the basis of death certificates. Deaths from lung cancer in asbestos cement workers were higher (standard mortality ratio (SMR) 1.7), but after adjustment for age and sex specific smoking habits this was not significant (SMR 1.04). The study had a probability of greater than 92% of detecting a smoking adjusted SMR of 1.5 or more. Using the best available evidence (including necropsy records) 52 deaths were assigned to lung cancer and five to mesothelioma. Life table analyses confirmed the predominant influence of smoking on lung cancer. Mesothelioma was associated with the use of crocidolite in pipe production. From present working conditions with much lower concentrations of chrysotile and no crocidolite no more occupational cancers are expected in the asbestos cement industry.

Asbestos↗

PubMed2006

Asbestos Surveillance Program Aachen (ASPA): initial results from baseline screening for lung cancer in asbestos-exposed high-risk individuals using low-dose multidetector-row CT.

The purpose of this study was to assess the prevalence of lung cancer in a high-risk asbestos-exposed cohort using low-dose MDCT. Of a population of 5,389 former power-plant workers, 316 were characterized as individuals at highest risk for lung cancer according to a lung-cancer risk model including age, asbestos exposure and smoking habits. Of these 316, 187 (mean age: 66.6 years) individuals were included in a prospective trial. Mean asbestos exposure time was 29.65 years and 89% were smokers. Screening was performed on a 16-slice MDCT (Siemens) with low-dose technique (10/20 mAs(eff.); 1 mm/0.5 mm increment). In addition to soft copy PACS reading analysis on a workstation with a dedicated lung analysis software (LungCARE; Siemens) was performed. One strongly suspicious mass and eight cases of histologically proven lung cancer were found plus 491 additional pulmonary nodules (average volume: 40.72 ml, average diameter 4.62 mm). Asbestos-related changes (pleural plaques, fibrosis) were visible in 80 individuals. Lung cancer screening in this high-risk cohort showed a prevalence of lung cancer of 4.28% (8/187) at baseline screening with an additional large number of indeterminate pulmonary nodules. Low-dose MDCT proved to be feasible in this highly selected population.

Aged↗