Mineral fibre analysis and routes of exposure to asbestos in the development of mesothelioma in an English region

OBJECTIVES: To compare the concentrations of inorganic fibres in the lungs in cases of mesothelioma and controls: to determine whether concentrations of retained asbestos fibres differ with the different exposures identified from interview; and to investigate the existence of a cut off point in concentrations of asbestos fibres that indicates occupational exposure. METHODS: Case-control study; 147 confirmed cases of mesothelioma and 122 controls identified from deaths occurring in four districts of Yorkshire between 1979 and 1991. Surviving relatives were interviewed to determine lifetime exposure history to asbestos. Mineral fibre analysis was carried out on lung tissue from postmortem examinations. RESULTS: Odds on high concentrations of retained asbestos fibres were greater in cases than controls. After excluding subjects with occupational and paraoccupational exposure, the odds on high concentrations were still greater in cases than controls, but only significantly so for amphiboles. There was only a weak relation between probability of occupational exposure to asbestos and concentrations of retained asbestos fibres, and no significant difference in fibre concentrations was found between subjects who had been exposed to asbestos through different routes: these comparisons were only based on small groups. There was considerable overlap in concentrations of retained asbestos fibres between cases and controls with and without histories of occupational exposure. CONCLUSIONS: The study has confirmed previous results of higher concentrations of asbestos fibres in cases than controls, and has shown that this is still found in subjects with little evidence of occupational and para-occupational exposure. The overlap in concentrations of retained asbestos for different groups of subjects did not suggest a clear cut of value.

 

     

Pericardial mesothelioma and asbestos exposure

Pericardial mesothelioma (PM) accounts for 0.7% of all malignant mesotheliomas. Although asbestos exposure is a recognized etiological factor for pleural and peritoneal mesotheliomas, its role in the development of PM is controversial. The aim of this study is to describe the characteristics of PM cases occurred in Lombardy, a highly industrialized Region of Northern Italy. From the Lombardy Mesothelioma Registry we selected the incident cases of PM registered in the Lombardy Region between 2000 and 2009 and we abstracted clinical characteristics and history of asbestos exposure. We identified 8 cases (6 men and 2 women), with a median age at diagnosis of 55.5 years, representing 0.3% of all mesothelioma cases (n = 3059). The age-standardized incidence rate was 0.09 per million/year. Occupational exposure to asbestos was documented in 5 of the 7 cases for which we obtained an interview. Our findings support the role of asbestos in the pathogenesis of PM.     

Pleura mesothelioma and exposure to asbestos

Summary The author reviewed literature data on the relationship between lead in blood levels (PbB) and various biochemical and haematological responses. PbB levels may be regarded as representative for internal dose. The percentage of subjects with a specified intensity of a specified response in groups of subjects has been calculated in relation to PbB. This Dose-Response (D-R) relationship portrays the increase of biological effects with increasing internal dose, qualitatively and quantitatively, and can be used to evaluate the health significance of Pb exposure in occupational and public health. D-R-curves have been calculated for -aminolaevulinic acid dehydratase activity in erythrocytes (ALAD), -aminolaevulinic acid excretion in urine (ALAU), protoporphyrin in erythrocytes (PPE), Na⁺-K⁺-ATPase activity in erythrocytes and reduced glutathion content of erythrocytes. Various other biochemical and haematological responses are discussed in regard to their relationship with PbB. In a subsequent paper the prevalence of functional effects in relation to PbB will be discussed.     

Histological types of malignant mesothelioma and asbestos exposure.

The Los Angeles County Cancer Surveillance Program abstracts hospital pathology records on almost all cases of cancer occurring in the county. Those cases of pleural and peritoneal mesothelioma that occurred between 1972 and 1978 were identified. Occupational histories were obtained from interviews, and the histopathology of the tumours was reviewed by a member of a mesothelioma reference panel who was unaware of the exposure histories. The relation of asbestos exposure to the three histological types of mesothelioma (epithelial, mesenchymal, and mixed) was studied among the 29 cases for whom occupational histories were available and who were also considered to have histopathology consistent with mesothelioma. The proportion of cases exposed to asbestos was high for both the epithelial (11/17, 65%) and mixed histological types (6/11, 55%). The single case of mesothelioma classified as a mesenchymal type was also exposed to asbestos. Cases who had worked in shipyards were represented in each of the three groups. In cases who had worked in asbestos production and manufacture an exclusively epithelial type of tumour was observed. In cases who had worked as insulators or in heating trades the histological type was predominantly (3/4) mixed. These data do not support the hypothesis that any specific histological type of mesothelioma is especially related to asbestos exposure.     

Malignant mesothelioma: attributable risk of asbestos exposure.

OBJECTIVES--To evaluate a case-control study of malignant mesothelioma through patterns of exposure to asbestos based upon information from telephone interviews with next of kin. METHODS--Potential cases, identified from medical files and death certificates, included all people diagnosed with malignant mesothelioma and registered during 1975-1980 by the Los Angeles County Cancer Surveillance Program, the New York State Cancer Registry (excluding New York City), and 39 large Veterans Administration hospitals. Cases whose diagnosis was confirmed in a special pathology review as definite or probable mesothelioma (n = 208) were included in the analysis. Controls (n = 533) had died of other causes, excluding cancer, respiratory disease, suicide, or violence. Direct exposure to asbestos was determined from responses to three types of questions: specific queries as to any exposure to asbestos; occupational or non-vocational participation in any of nine specific activities thought to entail exposure to asbestos; and analysis of life-time work histories. Indirect exposures were assessed through residential histories and reported contact with family members exposed to asbestos. RESULTS--Among men with pleural mesothelioma the attributable risk (AR) for exposure to asbestos was 88% (95% confidence interval (95% CI) 76-95%). For men, the AR of peritoneal cancer was 58% (95% CI 20-89%). For women (both sites combined), the AR was 23% (95% CI 3-72%). The large differences in AR by sex are compatible with the explanations: a lower background incidence rate in women, lower exposure to asbestos, and greater misclassification among women. CONCLUSIONS--Most of the pleural and peritoneal mesotheliomas in the men studied were attributable to exposure to asbestos. The situation in women was less definitive.     

The epidermiologic relationship between pleural mesothelioma and asbestos exposure.

This paper describes an investigation of 85 notifications of either probable or possible mesothelioma to the Finnish Cancer Registry from 1953 through 1969. The investigation covers characteristic epidemiologic features and the possibility of the mesothelioma being connected with occupational or other exposure to asbestos. The incidence rate of pleural mesothelioma was estimated at 1.1 per million per year. The male/female ratio was 1.3:1, which greatly differed fsrom that for malignant neoplasms of the bronchus or lung in Finland in 1960. The mean age at dealth from mesothelioma was over 7 years lower than that for bronchial carcinoma. The ratio of the crude incidence rates for the urban and rural populations was 4.2; the corresponding ratio for cases of carcinoma oopulations was 4.2; the corresponding ratio for cases of carcinoma of the bronchus or lung was 1.2 in Finland in 1960. THE LAST OCCUPATIONS OF THE 82 DECEASED PERSONS, OBTAINED FROM THE DEATH CERTIFICATES, WERE DIVIDIED INTO THREE CATEGORIES ACCORDING TO POSSIBLE ASBESTOS EXPOSURE. Exposure was present or probable in 9 (11.0) cases, 28 (34.2 %) had a possible exposure, and in 33 (40.2 %) cases exposure was absent or unlikely. The occupation of 12 (14.6) persons was unknown. Additional information of possible exposure history was obtained by interviewing the relatives of 10 mesothelioma patients. For half of the persons a definite, although in some cases trivial, exposure to asbestos could be ascertained. For the other five persons no exposure, either occupational, neighborhood or domestic, to asbestos could be traced. The residental distribution of the 85 persons with mesothelioma revealed no clustering of cases.     

Histological types of malignant mesothelioma and asbestos exposure

The Los Angeles County Cancer Surveillance Program abstracts hospital pathology records on almost all cases of cancer occurring in the county. Those cases of pleural and peritoneal mesothelioma that occurred between 1972 and 1978 were identified. Occupational histories were obtained from interviews, and the histopathology of the tumours was reviewed by a member of a mesothelioma reference panel who was unaware of the exposure histories. The relation of asbestos exposure to the three histological types of mesothelioma (epithelial, mesenchymal, and mixed) was studied among the 29 cases for whom occupational histories were available and who were also considered to have histopathology consistent with mesothelioma. The proportion of cases exposed to asbestos was high for both the epithelial (11/17, 65%) and mixed histological types (6/11, 55%). The single case of mesothelioma classified as a mesenchymal type was also exposed to asbestos. Cases who had worked in shipyards were represented in each of the three groups. In cases who had worked in asbestos production and manufacture an exclusively epithelial type of tumour was observed. In cases who had worked as insulators or in heating trades the histological type was predominantly (3/4) mixed. These data do not support the hypothesis that any specific histological type of mesothelioma is especially related to asbestos exposure.     

Malignant mesothelioma in Emilia-Romagna: incidence and asbestos exposure

This paper describes the activity, the sources of informations, methods and results of the "Emilia-Romagna Mesothelioma Registry" (ReM). The Registry started in 1996 and collects all cases of Malignant Mesothelioma (MM) occurring in Emilia-Romagna. 323 new cases (225 males and 98 females) have been detected during the period 1996-2001. Most cases (n = 286) concerned pleura. Other observed localizations were: peritoneum (n = 30), tunica vaginalis testis (n = 4) and pericardium (n = 3). Most of the cases were reported by the Institutes of Pathology and Occupational Health and by the Safety Services (respectively the 62% and the 18%). 87% of all the cases were histologically, 8% TC, 4% radiologically and only 1% clinically confirmed. The regional incidence rate (for 10(5) person-years, age standardized on the 1991 Italian population), has been estimated to be 1.98 in males and 0.88 in females. The highest rates were registered in Piacenza and Reggio Emilia province among men and Reggio Emilia and Ravenna province among women. 72% of cases have been classified as exposed to asbestos (64% occupationally and 8% as domestic/environmentally exposed).     

Determination of environmental exposure to asbestos (tremolite) and mesothelioma risks in the southeastern region of Turkey

In this study, the authors examined the concentrations and mineralogical analyses of asbestos, and investigated mesothelioma risk in southeastern Anatolia, Turkey. They used a gravimetric dust sampler to collect samples from 2 villages and 2 asbestos mines (1 active). Samples were then evaluated by an X-ray diffractometer and an electron microscope. The authors found high concentrations of asbestos in an active mine (4.9 fibers[f]/cm3) and at a house that was plastered with asbestos (1.24 f/cm3) and had a very active population. They found a low concentration (0.0042 f/cm3) in indoor measurements taken in Armutova village, and an even lower concentration (0.000081 f/cm3) in the inactive mine environment. Outdoor measurements included a low concentration of 0.007 f/cm3 in the village environment, and a high concentration of 1.17 f/cm3 on the mine road during the passing of a sheep herd. The people in the region are continuously exposed to asbestos during normal activities. This cumulative exposure to asbestos carries sufficient risks for mesothelioma development.     

Modeling mesothelioma risk associated with environmental asbestos exposure

BACKGROUND: Environmental asbestos pollution can cause malignant mesothelioma, but few studies have involved dose-response analyses with detailed information on occupational, domestic, and environmental exposures. OBJECTIVES: In the present study, we examined the spatial variation of mesothelioma risk in an area with high levels of asbestos pollution from an industrial plant, adjusting for occupational and domestic exposures. METHODS: This population-based case-control study included 103 incident cases of mesothelioma and 272 controls in 1987-1993 in the area around Casale Monferrato, Italy, where an important asbestos cement plant had been active for decades. Information collected included lifelong occupational and residential histories. Mesothelioma risk was estimated through logistic regression and a mixed additive-multiplicative model in which an additive scale was assumed for the risk associated with both residential distance from the plant and occupational exposures. The adjusted excess risk gradient by residential distance was modeled as an exponential decay with a threshold. RESULTS: Residents at the location of the asbestos cement factory had a relative risk for mesothelioma of 10.5 [95% confidence interval (CI), 3.8-50.1), adjusted for occupational and domestic exposures. Risk decreased rapidly with increasing distance from the factory, but at 10-km the risk was still 60% of its value at the source. The relative risk for occupational exposure was 6.0 (95% CI, 2.9-13.0), but this increased to 27.5 (95% CI, 7.8-153.4) when adjusted for residential distance. CONCLUSIONS: This study provides strong evidence that asbestos pollution from an industrial source greatly increases mesothelioma risk. Furthermore, relative risks from occupational exposure were underestimated and were markedly increased when adjusted for residential distance.     

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.