Asbestosis, laryngeal carcinoma, and malignant peritoneal mesothelioma in an insulation worker.

Asbestos associated diseases consist of both benign and malignant conditions. A rare constellation of asbestosis, laryngeal carcinoma, and malignant peritoneal mesothelioma occurring in a patient with long term occupational exposure to airborne asbestos fibres is presented. The observation illustrates the powerful disease-causing potential of occupational exposure to asbestos. A brief discussion of multiple primary neoplasms associated with exposure to asbestos is also presented.     

Diagnosis of malignant pleural mesothelioma and asbestosis

The incidence of malignant mesothelioma, the main consequence of exposure to asbestos, will increase considerably in the Netherlands in the coming decades. In the next 35 year, some 20,000 people will die from malignant mesothelioma. The diagnosis of malignant pleural mesothelioma in practice is based on histological examination in about 80%, on cytological examination in 15% and on other forms of examination, e.g., high resolution computer tomography (HRCT), in 6% of the cases. Using a combination of various noninvasive methods, such as anamnesis, physical and r?ntgenologic examination, HRCT and spirometry, the diagnosis of asbestosis is made erroneously in 5% of the patients examined. With regard to allowance of financial compensation to patients with pleural mesothelioma and asbestosis, a part is played by the fact that views differ internationally concerning the criteria on which the diagnosis should be based. For mesothelioma cytologic and histologic examination are the most important. For asbestosis, the Health Council considers HRCT as crucial, if necessary supplemented by histological examination, plus a history of exposure to asbestos and pulmonary dysfunction. In mesothelioma cytological and histological examination are the most important.     

Asbestosis, laryngeal carcinoma, and malignant peritoneal mesothelioma in an insulation worker

Asbestos associated diseases consist of both benign and malignant conditions. A rare constellation of asbestosis, laryngeal carcinoma, and malignant peritoneal mesothelioma occurring in a patient with long term occupational exposure to airborne asbestos fibres is presented. The observation illustrates the powerful disease-causing potential of occupational exposure to asbestos. A brief discussion of multiple primary neoplasms associated with exposure to asbestos is also presented.     

The additional risk of malignant mesothelioma in former workers and residents of Wittenoom with benign pleural disease or asbestosis

Aims: To examine the hypothesis that people with benign pleural disease or asbestosis have an increased risk of malignant mesothelioma beyond that attributable to their degree of asbestos exposure. Methods: Former workers and residents of the crocidolite mining and milling town of Wittenoom are participating in a cancer prevention programme (n = 1988). The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was read for evidence of benign pleural disease and asbestosis, using the UICC classification. Crocidolite exposure of former workers was derived from employment records and records of dust measurements performed during the operation of the asbestos mine and mill between 1943 and 1966. Based on fibre counts, exposure for former residents was determined using duration of residence and period of residence (before and after a new mill was commissioned in 1957) and interpolation from periodic hygienic measures undertaken from personal monitors between 1966 and 1992. Cox proportional hazards modelling was used to relate benign pleural disease, asbestosis, asbestos exposure, and mesothelioma. Results: Between 1990 and 2002, there were 76 cases of mesothelioma (56 of the pleura and 20 of the peritoneum). Cases had more radiographic evidence of (all) benign pleural disease, pleural thickening, blunt/obliterated costophrenic angle, and asbestosis than non-cases. Adjusting for time since first exposure (log years), cumulative exposure (log f/ml-years), and age at the start of the programme, pleural thickening (OR = 3.1, 95% CI 1.2 to 7.6) and asbestosis (OR = 3.3, 95% CI 1.3 to 8.6) were associated with an increased risk of peritoneal mesothelioma. There was no increased risk for pleural mesothelioma. Conclusion: The presence of benign pleural disease, in particular pleural thickening, and asbestosis appears to increase the risk of mesothelioma of the peritoneum, but not of the pleura beyond that attributable to indices of asbestos exposure in this cohort of subjects exposed to crocidolite.     

Asbestos content of lung tissue in asbestos associated diseases: a study of 110 cases

Diseases associated with asbestos exposure include asbestosis, malignant mesothelioma, carcinoma of the lung, and parietal pleural plaques. In this study the asbestos content of lung tissue was examined in groups of cases representing each of these diseases and in several cases with non-occupational idiopathic pulmonary fibrosis. Asbestos bodies (AB), which are the hallmark of asbestos exposure, were present in the lungs of virtually everyone in the general population and present at increased levels in individuals with asbestos associated diseases. The highest numbers of AB occurred in individuals with asbestosis, all of whom had levels greater than or equal to 2000 ABs/g wet lung tissue. Every case with a content of 100,000 ABs/g or higher had asbestosis. Intermediate levels occurred in individuals with malignant mesothelioma and the lowest levels in patients with parietal pleural plaques. There was no overlap between the asbestos content of lung tissue from patients with asbestosis and those with idiopathic pulmonary fibrosis. Lung cancer was present in half the patients with asbestosis, and the distribution of histological patterns did not differ from that in patients with lung cancer without asbestosis. The asbestos body content in patients with lung cancer was highly variable. Control cases had values within our previously established normal range (0-20 ABs/g). There was a significant correlation (p less than 0.001) between AB counted by light microscope and AB and uncoated fibres counted by scanning electron microscopy. The previous observation that the vast majority of asbestos bodies isolated from human tissues have an amphibole core was confirmed.     

Asbestos content of lung tissue in asbestos associated diseases: a study of 110 cases.

Diseases associated with asbestos exposure include asbestosis, malignant mesothelioma, carcinoma of the lung, and parietal pleural plaques. In this study the asbestos content of lung tissue was examined in groups of cases representing each of these diseases and in several cases with non-occupational idiopathic pulmonary fibrosis. Asbestos bodies (AB), which are the hallmark of asbestos exposure, were present in the lungs of virtually everyone in the general population and present at increased levels in individuals with asbestos associated diseases. The highest numbers of AB occurred in individuals with asbestosis, all of whom had levels greater than or equal to 2000 ABs/g wet lung tissue. Every case with a content of 100,000 ABs/g or higher had asbestosis. Intermediate levels occurred in individuals with malignant mesothelioma and the lowest levels in patients with parietal pleural plaques. There was no overlap between the asbestos content of lung tissue from patients with asbestosis and those with idiopathic pulmonary fibrosis. Lung cancer was present in half the patients with asbestosis, and the distribution of histological patterns did not differ from that in patients with lung cancer without asbestosis. The asbestos body content in patients with lung cancer was highly variable. Control cases had values within our previously established normal range (0-20 ABs/g). There was a significant correlation (p less than 0.001) between AB counted by light microscope and AB and uncoated fibres counted by scanning electron microscopy. The previous observation that the vast majority of asbestos bodies isolated from human tissues have an amphibole core was confirmed.     

Malignant mesothelioma of the pleura in a truck driver

BACKGROUND: Among the responsibilities of the health operators in the occupational health and safety services of the local health units in Lombardy (Italy) is the administration of standardized questionnaires for the investigation of possible occupational exposure to asbestos fibres in subjects diagnosed with malignant mesothelioma. OBJECTIVES: To describe a case of malignant mesothelioma in a truck driver suspected of being occupationally exposed to asbestos during the course of administration of the questionnaire. METHODS: Analysis of the literature regarding asbestos contamination of truck cabs. Some years ago Italian authors described a case of asbestosis in a truck-driver and findings of pollution by asbestos fibres in the cabs of some models of trucks. RESULTS: The subject had worked for more than 30 years as a truck driver operating on long distances on truck models described in literature as contaminated by asbestos fibres. He had not transported materials made of asbestos, and had not carried out maintenance on the trucks, nor had he any non-occupational sources of exposure to asbestos. Thus the mesothelioma was related to occupational exposure and procedures were initiated for reporting a suspected occupational disease.     

Immunological alterations found in mesothelioma patients and supporting experimental evidence

It is common knowledge that exposure to asbestos causes asbestos-related diseases, such as asbestosis, lung cancer and malignant mesothelioma, not only in people who have had long-term contact with asbestos in their work environment but also in residents living near factories that handle asbestos. Since the summer of 2005, these revelations turned into a large medical problem and caused and social unrest. We have focused on the immunological effects of both asbestos and silica on the human immune system. In this brief review, we introduce immunological alterations found in patients with malignant mesothelioma and describe the experimental background in which these were found. Analyzing the immunological effects of asbestos may improve our understanding of the biological effects of asbestos.     

Malignant mesothelioma from neighborhood exposure to anthophyllite asbestos

BACKGROUND: Anthophyllite asbestos has been reported to cause asbestosis, lung cancer, mesothelioma, and pleural plaques in occupationally exposed workers. Anthophyllite has also been associated with pleural plaques in Finland and Japan among those who live near mines and mills and have neighborhood or environmental exposure. METHODS: We evaluated a 38-year-old patient with pleural mesothelioma who lived, attended school, and delivered newspapers near a manufacturing facility that used exclusively anthophyllite asbestos fiber from ages 8-17 years. He had no work exposure to asbestos. RESULTS: The pleural mesothelioma was an epithelial type with tubulopapillary structures and was treated with an extrapleural pneumonectomy followed by radiation therapy. The malignant cells were positive by immunohistochemistry for cytokeratin but negative for carcinoembryonic antigen, S100, B72.3, and leu M1 antigen. Anthophyllite fibers were > 5 microm in length in lung tissue compared to 3 microm from a general population study. CONCLUSIONS: Anthophyllite asbestos has been associated with neighborhood environmental exposure and pleural plaques; we now report a neighborhood exposure and pleural mesothelioma.     

Epidemiology of occupational asbestos-related diseases in China

In 1950s and 60s, asbestosis had been a major health hazard for asbestos exposed workers. In the late 1970s, lung cancers with or without asbestosis were found among asbestos workers. All cohort studies on asbestos workers and on chrysotile miners in China showed excess deaths from lung cancer. In a large scale of cohort study on asbestos workers, a synergistic effect was found between cigarette smoking and asbestos exposure in the production of lung cancer. There have been not so many cases of malignant mesotheliomas reported, so far. In the cohort of chrysotile miners, 4 cases of pleural mesothelioma were observed. In the large scale of cohort study on asbestos workers in 9 factories using only chrysotile only one case of pleural mesothelioma was detected for 10 years' observation. In another 2 cohort studies, 2 cases of peritoneal mesotheliomas were found, one in Shanghai asbestos factory where a small amount of crocidolite had been used in 1960s, and one in Anqing asbestos factory that was located near tremolite mine. Further study is needed especially for the relationship between exposure to Chinese chrysotile and malignant mesotheliomas.     

Lung asbestos burden in shipyard and construction workers with mesothelioma: comparison with burdens in subjects with asbestosis or lung cancer

Although mesothelioma is generally considered to be caused by asbestos, epidemiologic studies indicate that some cases have another cause. In order to determine whether pulmonary asbestos burden can be used to define asbestos-related mesotheliomas, asbestos burden was quantified in 27 shipyard or construction workers with diffuse malignant mesothelioma of the pleura or peritoneum and a history of asbestos exposure. Their burden was significantly greater than the burden found in 19 unexposed men (P less than 0.001). The burdens were also compared to those of previously reported subjects with asbestosis or lung cancer. The median concentration for total amphibole fibers (2.7 million/g dry lung) in subjects with mesothelioma did not differ significantly from our previously reported median values for 14 subjects with asbestosis (1.3 million/g dry lung) or for 60 asbestos workers with lung cancer (1.3 million/g dry lung). Fiber size distribution for amosite, the most prevalent fiber type, was similar in all three subject groups. Fifteen of 25 (60%) subjects with mesothelioma had mild asbestosis. Asbestos body (AB) concentrations were greater than or equal to 1900/g dry lung, and total amphibole fiber concentrations were greater than or equal to 390,000/g dry lung. Counts of ABs greater than or equal to 0.5/cm2 in histologic sections always signified both of these concentrations in extracts. Thus, histologic sections showing greater than or equal to 0.5 ABs/cm2 or extracts containing asbestos body or amphibole fiber concentrations of at least 1900 or 390,000/g dry lung, respectively, will confirm an asbestos-related mesothelioma.     

Correlation between fibre content of the lung and disease in east London asbestos factory workers

The lungs from 36 past workers at an east London asbestos factory who had died from asbestos related disease were compared with lung tissue from 56 matched control patients being operated on in east London for carcinoma of the lung, correlating the severity of asbestosis and the presence of pulmonary carcinoma or mesothelioma of the pleura or peritoneum with an asbestos exposure index and type and amount of mineral fibre in the lungs. Asbestosis was associated with far heavier fibre burdens than mesothelioma. There was also a striking difference in the degree of asbestosis between the subjects with mesothelioma and those with carcinoma of the lung, the asbestosis being more severe in the latter. A further finding was that crocidolite and amosite were strongly associated with asbestosis, carcinoma of the lung complicating asbestosis, and mesothelioma, whereas no such correlation was evident with chrysotile or mullite. It is suggested that more emphasis should be placed on the biological differences between amphibole and serpentine asbestos fibre.     

Asbestos-related disease associated with exposure to asbestiform tremolite

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.     

Autopsy Cases of Asbestosis in Japan: A Statistical Analysis on Registered Cases

There are 525 (484 male, 38 female, 3 unknown) autopsy cases with asbestosis registered in the Annual of the Pathological Autopsy Cases in Japan, which is issued by the Japanese Society of Pathology for the years 1958-1996. The frequency of asbestosis (number of cases/total autopsy cases) was 0.017% (76/440,334) for the 1958-1979 time period, 0.058% (226/390,124) for 1980-1989, and 0.099% (223/225,801) for 1990-1996. There was a significant increase in asbestosis cases across the three time periods (p < .0001). The number of asbestosis cases increased markedly among individuals who worked with asbestos products, as well as among those employed in asbestos-processing factories. The frequency of malignant tumors associated with asbestosis was 61.0% (320/525), and the frequency also increased across the three time periods, from 43.4% (33/76) to 62.8% (142/226) and 65.0% (145/223), respectively. Among the 525 cases with asbestosis, there were 174 lung cancers (33.1%), 73 malignant mesotheliomas (13.9%), 29 stomach cancers (5.5%), 14 liver cancers (2.7%), 9 prostatic cancers (1.7%), 8 malignant lymphomas (1.5%), 6 laryngeal cancers (1.1%), 4 pancreas cancers (0.8%), 3 rectal cancers (0.6%), and 28 other cancers (5.3%). The frequencies of lung cancer, malignant mesothelioma, and laryngeal cancer were significantly higher in the cases with asbestosis than among the nonasbestosis cases. The number of malignant tumors related to asbestos exposure is expected to increase in the future.     

Correlation between fibre content of the lung and disease in east London asbestos factory workers.

The lungs from 36 past workers at an east London asbestos factory who had died from asbestos related disease were compared with lung tissue from 56 matched control patients being operated on in east London for carcinoma of the lung, correlating the severity of asbestosis and the presence of pulmonary carcinoma or mesothelioma of the pleura or peritoneum with an asbestos exposure index and type and amount of mineral fibre in the lungs. Asbestosis was associated with far heavier fibre burdens than mesothelioma. There was also a striking difference in the degree of asbestosis between the subjects with mesothelioma and those with carcinoma of the lung, the asbestosis being more severe in the latter. A further finding was that crocidolite and amosite were strongly associated with asbestosis, carcinoma of the lung complicating asbestosis, and mesothelioma, whereas no such correlation was evident with chrysotile or mullite. It is suggested that more emphasis should be placed on the biological differences between amphibole and serpentine asbestos fibre.     

Autopsy cases of asbestosis in Japan: a statistical analysis on registered cases

There are 525 (484 male, 38 female, 3 unknown) autopsy cases with asbestosis registered in the Annual of the Pathological Autopsy Cases in Japan, which is issued by the Japanese Society of Pathology for the years 1958-1996. The frequency of asbestosis (number of cases/total autopsy cases) was 0.017% (76/440,334) for the 1958-1979 time period, 0.058% (226/390,124) for 1980-1989, and 0.099% (223/225,801) for 1990-1996. There was a significant increase in asbestosis cases across the three time periods (p < .0001). The number of asbestosis cases increased markedly among individuals who worked with asbestos products, as well as among those employed in asbestos-processing factories. The frequency of malignant tumors associated with asbestosis was 61.0% (320/525), and the frequency also increased across the three time periods, from 43.4% (33/76) to 62.8% (142/226) and 65.0% (145/223), respectively. Among the 525 cases with asbestosis, there were 174 lung cancers (33.1%), 73 malignant mesotheliomas (13.9%), 29 stomach cancers (5.5%), 14 liver cancers (2.7%), 9 prostatic cancers (1.7%), 8 malignant lymphomas (1.5%), 6 laryngeal cancers (1.1%), 4 pancreas cancers (0.8%), 3 rectal cancers (0.6%), and 28 other cancers (5.3%). The frequencies of lung cancer, malignant mesothelioma, and laryngeal cancer were significantly higher in the cases with asbestosis than among the nonasbestosis cases. The number of malignant tumors related to asbestos exposure is expected to increase in the future.     

Health effects of asbestos exposure in humans: a quantitative assessment

Asbestos causes four diseases in humans: Lung fibrosis (asbestosis) follows heavy exposure and, in industrialized countries, is mainly a relic of past working conditions. The risk of pleural fibrosis and plaques is likely to be linearly dependent from time since first exposure and is present for all types of asbestos fibres. The diagnostic uncertainties regarding pleural plaques and the substantial degree of misclassification make it difficult to precisely estimate the shape of the dose-response relationship. The risk of lung cancer seems to be linearly related to cumulative asbestos exposure, with an estimated increase in risk of 1% for each fibre/ml-year of exposure. All fibre types seem to exert a similar effect on lung cancer risk; a multiplicative interaction with tobacco smoking has been suggested. Pleural mesothelioma is a malignant neoplasm which is specifically associated with asbestos exposure: the risk is linked with the cubic power of time since first exposure, after allowing for a latency period of 10 years, and depends on the fibre type, as the risk is about three times higher for amphiboles as compared to chrysotile. Environmental exposure to asbestos is also associated with mesothelioma risk.     

Mortality of asbestos workers in England and Wales 1971-81.

A national study of British asbestos workers is briefly described and the mortality experience of 31 150 male asbestos workers in England and Wales who had been medically examined at least once as part of that survey is presented. The survey population is divided into workers with occupational exposure to asbestos before the inception of the 1969 Asbestos Regulations and those who worked with asbestos only after 1969. Of the 1128 who had died, 897 had worked before 1969; 34 of the death certificates received for these men mentioned mesothelioma and for another nine asbestosis was reported in the absence of mesothelioma or lung cancer. A statistically significant excess of lung cancer (SMR 136) was found. For the post-1969 workers, one case of asbestosis and one case of mesothelioma were reported, but further investigation of these cases showed probable occupational exposure to asbestos many years before 1969. The time from first exposure for this section of the population is too short to exclude an excess of asbestos related disease. The most noticeable excess of asbestos related disease was seen among the insulation workers who had more than twice (SMR 256) the expected number of deaths from lung cancer, and for whom almost 10% of all death certificates mentioned mesothelioma. No excess of any alimentary tract cancer was found and the population showed a significant deficit of large bowel cancer mortality (SMR 54).     

The prevalence of pleural plaques and/or pulmonary changes among construction workers in Okayama, Japan

BACKGROUND: Since asbestos has been widely used in Japanese building materials since 1960s, a large number of Japanese construction workers may be exposed to asbestos occupationally. METHODS: Among 2951 construction workers in Okayama, Japan, the prevalence of asbestos-induced pleural or pulmonary changes was examined by screening chest x-rays; these findings were confirmed by computed tomography (CT) scanning of the chest. RESULTS: Among 2951 construction workers, 168 (5.7%) were found to have significant findings for pleural plaque or pulmonary changes on chest x-ray. Seventy-four had both pleural plaque and asbestosis, 85 pleural plaques alone, and 9 asbestosis alone. In 11 subjects, pleural plaques were suggested by chest x-ray, but neither pleural plaque nor asbestosis was demonstrated by chest CT. Honeycombing as one of the characteristic findings of asbestosis was found in 29 subjects. Others showed subpleural spots or curvilinear shadow, which suggested the early stage of asbestosis. The occupations of these workers were carpenters (64), plasterers (27), and concrete board cutters (14). About 30% of the workers with these findings were aware that they were handling asbestos in activities such as installation of asbestos boards, and/or asbestos spraying. CONCLUSIONS: As the incidence of malignant mesothelioma and primary lung cancer associated with asbestos exposure are high, screening by chest CT is necessary for detecting asbestos-induced pulmonary and/or pleural lesions. Education for protection such as telling about the presence of asbestos in building materials is also necessary.     

Chrysotile asbestos and health in Zimbabwe: I. Analysis of miners and millers compensated for asbestos-related diseases since independence (1980)

Data on the health effects caused by locally mined chrysotile asbestos in Zimbabwe have been very limited. The prevailing local view has been that risk is minimal. In this report we critically reassess the cases of 51 individuals with asbestos exposure who have been compensated by the Central Pneumoconiosis Bureau since independence in 1980. Results demonstrate that the major health risks of exposure reported elsewhere--morbid asbestosis, nonmalignant pleural disease, malignant mesothelioma, and lung cancer--all occur in Zimbabwe, at least among workers in the asbestos mines and mills. It is concluded that further investigation and control measures in the industry are warranted.