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PubMed1999

[Role of biometric analysis in the retrospective assessment of exposure to asbestos].

Despite intrinsic limitations due to differences in the bio-persistence of the various asbestos types, in the definition of control populations and in analytical techniques used by the laboratories, mineralogical analysis of biological samples is useful in the assessment of past exposure to asbestos. It provides additional information to occupational and environmental questionnaires, particularly when exposure to asbestos is doubtful, unknown or forgotten by a subject. Results should be interpreted taking into account clinical information. A positive result does not mean existence of asbestos-related disease. A negative result does not exclude previous significant asbestos exposure, clearly identified by an occupational questionnaire (particularly for exposure to chrysotile). Threshold values indicative of a high probability of previous asbestos exposure have been established for bronchoalveolar lavage fluid (BALF) samples and lung tissue samples. Quantification of asbestos bodies by light microscopy is easy to perform. Sensitivity and specificity of this analysis towards the total pulmonary asbestos fiber burden is good. Therefore this analysis should be performed first. Mineralogical analysis in BALF or lung tissue should be considered only when sampling is supported by diagnostic or therapeutic implications.

Asbestos↗

PubMed2003

Malignant and non-malignant asbestos-related pleural and lung disease: 10-year follow-up study.

AIM: To examine the presence of radiologically visible lung and pleural changes in patients who were exposed to the asbestos dust, and to correlate the progression of these changes with the duration and intensity of exposure and smoking. We also evaluated possible correlation between non-malignant asbestos-related pleural abnormalities and the occurrence of malignant pleural mesothelioma. METHODS: Among 7,300 patients who visited our department between 1991 and 2000 due to non-specific respiratory symptoms, we selected 2,420 with chest X-rays indicating the possible existence of non-malignant asbestos-related diseases. The selected group was followed-up for progression of radiological changes and the development of malignant pleural mesothelioma, and the changes were correlated with the intensity and duration of exposure to asbestos dust and smoking. RESULTS: Radiological changes characteristic for non-malignant asbestos-related pleural disease or lung asbestosis were identified in 340 (14%) out of 2,420 examined patients, of whom 77 (22.6%) developed malignant pleural mesothelioma, as compared with 13 patients out of 2,080 (0.6%) without radiological signs of asbestosis or pleural changes. Twenty-three (29.9%) patients who presented with a progression of pleural disease and lung asbestosis had a very significant incidence of malignant pleural mesothelioma (p<0.001). We also found that 55 (71.4%) patients with the highest asbestos exposure level (grade 3) developed malignant pleural mesothelioma more often (p=0.044). No correlation was found between malignant pleural mesothelioma development and duration of asbestos exposure (p=0.149) or smoking habit (p=0.617). Professionally exposed patients were at 3.3-times higher relative risk (95% confidence interval, 2.28-4.75) than those who were not exposed to develop malignant pleural mesothelioma. CONCLUSIONS: The risk of developing lung asbestosis increased with the level of exposure to asbestos dust and smoking. The risk of developing pleural disease correlated with the intensity and duration of exposure, but not with smoking. The patients with progressive pleural and parenchymal changes are at particularly high risk of developing malignant pleural mesothelioma and must be under special surveillance.

Adolescent↗

PubMedDate not supplied

[Epidemiologic research on asbestos related disease in ENEL SpA electricity production plant maintenance].

Since many years research programs have been set up to study the relationship between asbestos occupational exposure and development of asbestos-related lung diseases in electricity production plants workers. In the year 2000 a new study of asbestos-related lung abnormalities prevalence in italian geothermal and idrothermal power plant maintenance workers was planned. The cohort comprised 3891 subjects. To meet the criteria, only workers in service for at least six months before 1990 and still in service at power plants in May 2000 were included in the study; chest X-rays were taken and made anonymous. Independent reading of X-rays was made by two groups of specialists, and a third reading of selected discordant readings X-rays was made by another group of specialists. A further diagnostic protocol (including HRCT) was planned when two out of three readings showed the presence of asbestos related lung abnormalities. The analysis was made on 3063 subjects (78.7% of the cohort). The number of asbestos-related abnormalities in two out of three X-ray readings was 122 (4%). The further diagnostic protocol, that included occupational and pathological anamnesis and HRCT, confirmed an asbestos-related occupational lung abnormalities in 41 cases (1.3% out of 3063 subjects). The prevalence of asbestos-related lung abnormalities among 3063 power plant maintenance workers was 1.3%. If all the cases of lung abnormalities so far detected (data are still provisional) had developed only in the power plant environment, and not in previous working activities, the prevalence of lung abnormalities would be extremely low. These data support the evidence of limited exposure levels to asbestos in this working environment And bears witness to the success of preventive measures to control this specific risk.

Asbestos↗

PubMedDate not supplied

[Asbestos risk: past and present exposure].

Occupational asbestos exposure affected a large number of workers during the last century. In particular, during the period following the second world war until the end of the eighties heavy exposures occurred in several industrial divisions. An approximate data can be represented by the number of requests for compensation according to the n. 257/1992 ban asbestos law. The National and Regional Mesothelioma Registries collect all the cases of this asbestos related disease. Analysing these data, the industrial divisions at risk, considering both intensity and quality of exposure, emerge with increasing accuracy. The use of asbestos in new products has been banned in Italy since 1992. The legislation issued during the nineties includes technical guidelines for exposure risk control during operations on asbestos containing products, mainly consisting in maintenance or asbestos removal. Consequently, the exposures decreased, both in terms of intensity and in terms of number of exposed workers but exposures will reach a complete end only when asbestos is completely cleared out. In this paper, data about industrial divisions at major risk, derived from the tuscanian cases, as well as the list of the jobs of the present asbestos exposed workers are illustrated.

Asbestos↗

PubMed2004

[Epidemiological features of bronchial carcinoma cases with environmental asbestos exposure].

Due to environmental asbestos exposure, asbestos related lung diseases are common in Eskisehir district of Anatolia. In this study we aimed both to determine the epidemiological findings of the patients diagnosed as bronchial carcinoma and to discuss the features, which were probably related to asbestos exposure, presented by the patients. From May 1997 to December 2000, 301 cases were included in the study. Of the patients, 97 (32.2%) had epidermoid cell type, 84 (27.9%) had small cell, 39 (13%) had adenocarcinoma, 4 (1.3%) had large cell. Adenocarcinomas were more frequent in women. There were not significant differences among the cell types from the point of view of the age distributions. Adenocarcinomas were more frequently located in lower lobes of the lungs (36.9%) and more frequently showed peripheral locations (45.9%) than other cell types (20.6% for epidermoid and 14.6% for small cell). Pleural effusion was more detected in adenocarcinomas (48.7% to 17.3% in epidermoid, 18.3% in small cell). The duration of smoking was shortest in adenocarcinomas, mean 32.4 years; the same duration was 56.2 years for epidermoid carcinomas. Of the patients, 54% had asbestos exposure. Adenocarcinomas were more frequently detected in the patients who exposed to asbestos but did not smoke. Our findings support that asbestos exposure may increase adenocancer frequency. The epidemiological and clinical features of adenocancer cases exposed to asbestos environmentally were not different than those of adenocancer cases exposed to asbestos occupationally.

Adenocarcinoma↗

PubMedDate not supplied

National epidemiologic surveillance systems of asbestos-related disease and the exposed workers register.

INTRODUCTION: Italy was the main European producer of asbestos for most of the 20th century and raw asbestos imports wee also significant until the 1990's; there was a mean delay of about ten years in the pattern of asbestos consumption in Italy compared with the USA, Australia, UK and Scandinavian countries. METHODS: A national surveillance system (ReNaM) was implemented to identify cases of mesothelioma and investigate the modalities of asbestos exposure. A register of exposed workers and a database of companies presumably involved in the asbestos exposure problem was also developed. ReNaM has a regional structure and an operative centres (COR) have been established in 16 Italian regions. RESULTS: The ReNaM database currently contains more than 5,000 mesothelioma cases and for 3,500 of these exposure modalities have been defined. Cases of pleural mesothelioma represent 93% of the total but there were also 334 cases of peritoneal mesothelioma, 15 of the pericardium and 14 of the tunica vaginalis of the testicle. Cases with ascertained exposure are thus distributed: 67.4% occupational exposure (ascertained, probable, possible), 4.3% domestic, 4.2% environmental and 1.3% hobby-related exposure, totalling 77.2%; 22.8% had unlikely or unknown exposure. The latency period is very long: on average 43.6 years. The register of asbestos-exposed workers contains figures on exposed workers notified to ISPESL up to 2004 and refers to the exposure period 1993-2003. The data registered cover 160 firms and about 700 workers. CONCLUSIONS: A national, coordinated and uniform epidemiological surveillance system of cases of mesothelioma and the definition of asbestos exposure through active research is extremely important in identifying unexpected contaminating sources. The register of asbestos-exposed workers allows risk to be monitored and protection measures to be implemented.

Aged↗

PubMed1991

Exposure to asbestos in Monfalcone, Italy. A necropsy-based study.

The Monfalcone area in north-eastern Italy (total population, about 60,000) is a small industrial district in which shipbuilding is the main industry. We examined thoracic cavities for hyaline pleural plaques and routine lung sections for asbestos bodies in 1765 necropsies performed at Monfalcone Hospital. In 553 cases, we also isolated and quantified asbestos bodies in the lungs (Smith-Naylor's method). Occupational histories were obtained from the relatives of 798 patients. The prevalence of pleural plaques was significantly higher (p less than 0.001) among residents of the Monfalcone region (73.6% of men, 26.7% of women) than among nonresidents. Similarly, asbestos bodies were found more frequently in lung sections from residents. A good correlation was observed between pleural plaques and the asbestos body content of the lung (Spearman's correlation coefficient, 0.53). Different occupational groups showed very marked differences in the prevalence of plaques in general, in the prevalence of large plaques and in the numbers of asbestos bodies in the lung. Subjects who had worked in the shipyard or in a sodium carbonate factory had the highest indices. Exposure to asbestos had occurred at work for the large majority of men for whom data on occupation had been collected and through domestic contacts for the large majority of women. In a small portion of cases, environmental exposure could not be excluded as the cause of the objective signs. Pleural plaques, the asbestos body content of the lungs and occupational history must be considered together in monitoring exposure to asbestos in a given geographical area.

Adult↗

PubMed1991

Cigarette smoking, asbestos exposure, and malignant mesothelioma.

In a hospital-based case-control study of 124 (105 male and 19 female) histologically confirmed malignant mesothelioma cases and age- and sex-matched controls, the role of cigarette smoking and the risk of asbestos exposure was investigated. Exposure to asbestos for at least 1 year was likely for 78% of male cases and 16% of female cases, and 90% of males were possibly exposed. Male cases worked predominantly in the ship-building industry, construction, or insulation trades. Elevated risks were found for males employed in asbestos-related industries [odds ratio (OR) 8.1; 95% confidence interval (CI) 4.9-13.5], e.g., shipyards (OR 82.9, 95% CI 25.5-269.1), construction/maintenance (OR 8.3, 95% CI 4.6-14.8), and other asbestos-related jobs (OR 3.2, 95% CI 1.4-7.2), and for males who self-reported exposure to asbestos or insulation (OR 50.9, 95% CI 21.7-119.8). A statistically significant trend was found for the risk of mesothelioma with increasing years employed in non-shipyard asbestos-related occupations. Among women, only one case worked in an asbestos-related industry and two reported domestic contact with asbestos. No association between cigarette smoking and mesothelioma was found for either men or women. We also report the occurrence of mesothelioma in occupations which have not been previously reported.

Adult↗

PubMed1990

[Occupational and non-occupational effects of asbestos].

Forty-eight cases of mesothelioma from the National Cancer Register, and 19 cases of pleural plaques were investigated for non-occupational exposure to asbestos, and compared with results obtained in earlier studies on occupational asbestos-induced lesions. The results of the investigation confirmed reports in the literature indicating that even in the non-occupational area, asbestos represents a non-negligible risk, in particular for diseases of the lungs. Individual causes proved to be the cleaning by members of the family of working clothes contaminated with asbestos in 46% of the cases, followed by the use of asbestos-containing materials in the household (20.9%) or in connection with leisure activities (14.9%). In addition, exposure to asbestos fibre emissions of people living close to an asbestos-processing plant were observed. Recognition of the condition as an occupation-related disease is not possible. The consequence to be drawn from these data is that, in accordance with present regulations, the use of asbestos-free materials in the home and in the area of leisure activities must be promoted. In this way, such lesions can be avoided in the future.

Air Pollutants, Occupational↗

PubMed1989

[The carcinogenic effect of asbestos].

There is a causal correlation between the inhaled dose of asbestos at the working place, the occurrence of asbestosis, and a 5-fold increased mortality rate of lung cancer. Mesothelioma, which appears to be very rare among the general population, is a specific sign of exposure to asbestos fibres. Malignant tumours of the urinary bladder, the gastro-intestinal tract, the larynx and the oesophagus in workers may also be ascribed to the specific exposure in some cases. After a brief outline of the epidemiology of these diseases the carcinogenic effects of asbestos on the cellular and subcellular level are described. It can be shown from most recent literature that asbestos fibres can also trigger epigenetic and genotoxic effects. Numeric mutation of chromosomes, damage of the plasma membrane, and a modification of the immune system are most significant. In the presence of PAH, asbestos acts as a cocarcinogen. Asbestos fibres are positive in the cellular transformation test. Due to its initiating and promoting effects, asbestos proves to be a complete carcinogen. Obviously, asbestos fulfils the criteria of the modern theory of carcinogenesis as a multicausal and multistep process.

Air Pollutants↗

PubMed1989

Airborne asbestos levels in non-occupational environments in Japan.

Airborne asbestos levels in non-occupational environments in Japan were determined by analytical transmission electron microscopy (ATEM) for about 100 air samples from various outdoor settings. Asbestos fibres (chrysotile) were found in almost all samples. The fibre (mass) concentrations were in the range of 4-367 fibres per litre (0.02-47.2 ng/m3) with a geometric mean of 18 f/1 (0.3 ng/m3). The mass concentrations were similar to the earlier data reported from other countries. Samples from main roads showed extremely high asbestos concentrations and short fibre lengths compared with those of the other samples. This strongly suggested that braking of vehicles was a significant emission source of airborne asbestos. Laboratory experiments using a brake testing machine demonstrated that asbestos fibres were released during braking. In addition, the present study found high levels of airborne asbestos in some highly polluted areas, such as a serpentine quarry, a town adjacent to an asbestos mine, and factories making asbestos slate-board. On the other hand, chrysotile fibres were also found in air samples from a small isolated island in the Pacific Ocean as well as in ice samples from ten thousand years ago in Antarctica. These facts suggest that chrysotile fibres have been liberated both by industrial activities and natural weathering, and have circulated around the earth.

Air Pollutants↗

PubMed1986

Enhancement of benzo[a]pyrene-induced sister chromatid exchanges in lymphocytes from cigarette smokers occupationally exposed to asbestos.

The frequencies of base-line and benzo[a]pyrene [(BP) CAS 50-38-8]-induced sister chromatid exchanges (SCE) were measured in peripheral blood lymphocytes from 22 male asbestos-exposed workers and 10 nonexposed workers of comparable age. A clear association between cigarette smoking and asbestos exposure in the sensitivity of lymphocytes to BP was observed. Among asbestos-exposed workers, lymphocytes from those who smoked cigarettes were significantly more susceptible to the induction of SCE by in vitro exposure to BP (P = .01) than were lymphocytes from nonsmokers. Active smoking elevated the base-line SCE frequency in both asbestos-exposed and nonexposed workers (P = .001), and an interaction between smoking and asbestos in the production of base-line SCE was suggested (P = .07). Asbestos exposure alone was not associated with an enhanced susceptibility to the induction of SCE by BP or with an elevation of base-line SCE. Increased age was associated with an increase in SCE inducibility by BP (P = .01), and a history of smoking was marginally associated with SCE inducibility by BP (P = .07). These findings support the hypothesis that an increased susceptibility of asbestos-exposed individuals to polyaromatic hydrocarbon-induced cancer results from an enhanced sensitivity to the induction of genetic damage rather than to an asbestos-induced differential cellular metabolic capacity.

Adult↗

PubMed1986

Alteration of superoxide dismutase activity in tracheal epithelial cells by asbestos and inhibition of cytotoxicity by antioxidants.

We report here the inhibition of asbestos-induced cytotoxicity in a hamster tracheal epithelial cell line by superoxide dismutase, a scavenger of superoxide (O2-.), and by mannitol and dimethylthiourea, scavengers of the hydroxyl radical (OH.). By using these agents, cell damage was ameliorated in cultures exposed to long (greater than 10 microns in length) fibers of chrysotile and crocidolite asbestos. In contrast, injury to epithelial cells by short (less than or equal to 2 microns) chrysotile or glass fibers was not prevented by scavengers of O2-., OH., H2O2 or 1O2 (singlet oxygen). These results implicate active oxygen species as mediators of injury by long asbestos fibers to cells of the respiratory tract. By using immunocytochemical and biochemical techniques, we detected appreciable amounts of copper-zinc superoxide dismutase in hamster tracheobronchial epithelial cells and alveolar macrophages in vitro and in histologic sections of rat and human respiratory tract. Activity of total endogenous superoxide dismutase (copper-zinc and manganese forms) increased in tracheal epithelial cells exposed for several days in vitro to either crocidolite or chrysotile asbestos but was unchanged in untreated cells and those exposed to comparable amounts of glass fibers. After inhalation of asbestos by rats, or exposure of cells in culture to asbestos, long fibers were observed protruding from both epithelial cells and alveolar macrophages. The unsuccessful phagocytosis of long fibers of asbestos coupled with generation of oxygen free radicals might explain the increased pathogenic potential of long fibers in asbestos-associated diseases of the respiratory tract.

Animals↗

PubMed1983

Influence of asbestos on the uptake of benzo(a)pyrene and DNA alkylation in hamster tracheal epithelial cells.

The objective of these experiments was to understand the mechanism of cocarcinogenicity of asbestos and polycyclic aromatic hydrocarbons. Benzo(a)pyrene [B(a)P] was coated onto crocidolite or chrysotile asbestos fibers, resuspended in serum-free medium, and added to cultures of hamster tracheal epithelial cells. The fibers markedly enhanced cell uptake of B(a)P. Although considerable metabolism occurred, approximately 40% of the applied B(a)P was retained by the cells after 8-hr incubation as opposed to 5% after incubation with B(a)P in the absence of asbestos. The hydrocarbon-containing medium was replaced by fresh medium. Four days later, approximately 3% of the B(a)P that had been applied when adsorbed to asbestos was still persistent in cells as compared to 0.5% in cells treated with B(a)P alone. DNA from hamster tracheal epithelial cells was purified, and the amount of B(a)P alkylation was assessed. At 8 hr, the extent of alkylation after treatment of the cells with either B(a)P or B(a)P:asbestos was similar. However, the retained unmetabolized B(a)P was subsequently metabolized and contributed to further alkylation so that the B(a)P-asbestos treated cells demonstrated considerably higher levels of alkylation throughout the 4-day posttreatment period. None of these effects was observed if asbestos was added 1 hr before the addition of B(a)P. The enhanced uptake of B(a)P and subsequent additional alkylation of DNA might represent a mechanism of asbestos-induced cocarcinogenesis.

Alkylation↗

PubMed1982

[Contribution to importance of asbestos in the epidemiology of bronchial cancer].

Today asbestos is the most important professional carcinogenic agent of the respiratory tract. Asbestos caused bronchial cancer doesn't differ from its well-known morphology, progress and prognosis, but almost it is starting earlier. Fibrous form of asbestos represents its determinant potency. Carcinogenic fibres are about or below 1 micron in diameter and part of them can't be seen in light optical systems. Curious bodies may be missed sometimes also. A cancerogenic limit of asbestos concentration can't be quoted exactly now. Asbestos exposition during 60 contacting days or more are able to induce cancer. Cancerogenesis itself is during 20-30 years until clinical manifestation on an average. If the exposition is started in the youth, the period of latency is shortened distinctly. Tobacco smoke inhalations increase the carcinogenic effectiveness multiplicatively. In the districts of Magdeburg and Halle (GDR) more than 10% of the bronchial cancers are expected to be induced by asbestos. On the other hand only about 3% of the adults have had asbestos contacts at any former time. This is a raising of risk to at least triple rate.--It is necessary to realize all demands on technical prophylaxis of occupational asbestos exposition.

Adult↗

PubMed1982

[Correlations between selected indicators of asbestos dust pollution of the work environment].

Occupational exposure to asbestos dust induces many diseases, of which the most dangerous are: asbestosis, pulmonary cancer and pleural endothelioma. Exposure to asbestos dust is evaluated by: total gravimetric concentration of dust, gravimetric concentration of respirable fraction or numerical concentration of asbestos fibres of over 5 microns. The research has been aimed to establish whether or not there are correlations between the mentioned indices of asbestos dust exposure. The concentrations have been measured at various workstations in the plants producing textile asbestos products, frictional and asbestos--cement products. The gravimetric concentrations have been determined using the filtration--gravimetric method with cyclonic pre-selector and without selector. The numerical concentration of fibres has been determined by a microscopic phase--contrast method. The statistical analysis of the obtained results showed no correlation between particular indices, or--weak correlations (r = 0.004-0.76). No correlation has been found between total gravimetric concentration and numerical concentration of asbestos fibres. The ratio between those concentrations was 0.094-4.69, therefore both those concentrations should be included while evaluating the working conditions of those exposed to asbestos dusts.

Air Pollutants↗

PubMed1981

Epidemiology of asbestos-related tumors.

Epidemiologic evidence has helped in defining and measuring the risks of asbestos exposure. Further investigations are required to confirm the differing carcinogenicity of the various types of asbestos and related fibers. The evidence relating crocidolite asbestos to malignancy is not universally accepted. Most standards for concentrations of asbestos in the air are currently being adopted and the proposed British standard is about to be reduced to 1 fiber per milliliter for chrysotile asbestos, 0.5 fiber per milliliter for amosite and is to remain at 0.2 fiber per milliliter for crocidolite asbestos. 37 Careful prospective studies are still required in order to evaluate the efficacy of these standards in the prevention of asbestos related diseases. In addition, further epidemiologic studies are necessary to determine the relationship between asbestos exposure, particularly the low level exposure, and its potential cocarcinogenic role with other carcinogens in the evolution of the wide spectrum of human malignancy.

Asbestos↗

PubMed1994

[Relationship between asbestos exposure and malignant pleural mesothelioma: occurrence near the old Japanese naval shipyard].

Kure City, Hiroshima Prefecture, was the site of a Japanese naval shipyard before World War II, and commercial ships were built there after the War. Large amounts of asbestos were used in this area primarily for shipbuilding, from before the war to around 1975. Probably due to exposure to asbestos, the incidence of malignant pleural mesothelioma is high in this city. Of the 31 patients with this disease, 27 were men. Patients over 60 years of age constituted a high percentage of the total and 28 had a history of asbestos exposure: 12 in the Japanese naval shipyard and 12 in the commercial shipyards. The average period of asbestos exposure for these 28 patients was 20 years. Malignant pleural mesothelioma developed more than 40 years after the first exposure to asbestos. Many asbestos particles and fibers were detected in the lungs and tumors of these patients. Most of the asbestos fibers detected were crocidolites or amosites. Considering that the amount of asbestos used in Japanese has been higher than in any other country, the incidence of malignant pleural mesothelioma may be expected to increase in this country. Countermeasures are now advisable.

Aged↗