Asbestos and peritoneal mesothelioma among college-educated men

The proportion of peritoneal mesotheliomas among all mesotheliomas has been decreasing, leading some to suggest that peritoneal mesothelioma occurs only after high levels of exposure to asbestos. To investigate the relationship between asbestos exposure and the development of peritoneal mesothelioma, a case-control study examined 40 cases of primary peritoneal mesothelioma from a single institution. This series differed from previous reports in that 75% of the cases and controls had attended college. Results show an odds ratio of 6.6 for asbestos exposure among this group of primary peritoneal mesothelioma cases with relatively slight asbestos exposures.     

Malignant mesothelioma--German mesothelioma register 1987-1999

Objectives: The study group comprised a collective of 1,605 patients with malignant mesotheliomas and with lung tissue available for lung dust analyses. Method: Clinical features, occupational histories, expositions and individual data were evaluated, and the asbestos bodies concentrations (asbestos bodies/cm³ lung tissue or g wet tissue) were determined. Results: Mesotheliomas developed mainly in men (94.5%). Of the cases, 96.4% were of pleural origin and only 3.3% were peritoneal mesotheliomas. The biphasic subtype predominated (61.3%), followed by the epithelioid type (29.3%). The sarcomatoid subtype was rarely developed (9.4%). Mean age at first diagnosis was 60.4 years. The mean survival time from time of symptom onset was 13.5 months. Patients with epithelioid subtypes had a longer survival time (16.9 months) than those with biphasic (13.1 months) and sarcomatoid subtypes (5.5 months). Of the patients, 73% presented pleural effusions as initial symptoms of the disease. An increased asbestos burden was identified by light microscopy in 84.8% of the patients. There was no association between histological subtypes and the asbestos burden of the lungs. Patients with peritoneal mesotheliomas had distinctly higher asbestos burdens in the lungs than patients with pleural mesotheliomas. There exists no association between lung asbestos burdens and survival times. The mean latency period was 37.8 years. A trend: higher asbestos burden of the lung/shorter latency periods was suggested. About 70% of the patients had a history of occupational exposure to asbestos dust. Most patients worked in the building trade, the locksmith and machine building industries and in the steel and blast-furnace industries. Of the patients, 25.6% had asbestos-associated lung fibroses, in 40.7% of the cases pleural plaques were identified. Conclusions: The most important causal factor for development of mesotheliomas is still asbestos, primarily amphibole asbestos. The recurring occurrence of mesotheliomas in younger people without known asbestos exposure needs the urgent investigation of other inducing factors for mesotheliomas. Received: 11 September 2000 / Accepted: 20 February 2001     

Malignant pericardial mesotheliomas and asbestos exposure: A case report

Three cases of malignant pericardial mesotheliomas are presented with evidence of occupational asbestos exposure. Examination results are compared with findings from experimental and epidemiological research on biological effects of asbestos dust. There are sufficient indications that time-limited effects of asbestos dust established either by measurements or assessment of the amount of concentration after a latency of more than 20 years are apt to result in the development of mesotheliomas of the pleura and peritoneum and, moreover, the pericardium. It is suggested that malignant pericardial mesothelioma also be recognized as another form of occupational disease caused by asbestos dust.     

Asbestos exposure and differences in occurrence of peritoneal mesothelioma between men and women across countries

Objective

In several countries the incidence of peritoneal mesotheliomas among women closely mirrors the pattern among men. The aim was to investigate the role of asbestos exposure in the aetiology of peritoneal mesotheliomas in women and men.

Methods

All cases of peritoneal mesothelioma were selected from the Swedish and Netherlands Cancer Registers for the period 1989–2003. For both countries incidence rates were calculated and stratified by sex. A linear regression analysis was used to analyse the existence of a trend over time.

Results

Among men the incidence rate of peritoneal mesothelioma in the Netherlands (0.60 per 100 000 persons) was consistently higher than in Sweden with an average ratio of 1.8 (range 1.4–2.8). In both countries no trend over time was observed. During the 15-year period in the Netherlands the incidence rate among men was about 3.3-fold higher than among women. In Sweden the incidence rate among women was slightly higher than in men up to 1999, and thereafter about threefold higher among men. This sudden shift was statistically significant and seemed mainly caused by changes in classification of peritoneal tumours.

Conclusion

The absence of a time trend in the incidence rate of peritoneal mesothelioma in the Netherlands and Sweden in the past 15 years may point to a more limited role of occupational exposure to asbestos in the aetiology of peritoneal mesothelioma than for pleural mesothelioma, especially among women. The observed drop around 2000 in annual incidence of peritoneal mesothelioma among Swedish women indicates the presence in the past of a substantial misclassification with other tumours in the peritoneum.In many Western countries the pleural mesothelioma incidence among men has increased dramatically in the past 30 years.¹ In recent years in some countries a deceleration or leveling off of mesothelioma rates has been observed,^2,3,4 whereas in other countries the mesothelioma incidence is still expected to rise until 2020.^5,6,7 These trends have been attributed to occupational exposure to asbestos which has been substantial throughout the workforce from the 1930s up to the 1980s. It was estimated that among men with pleural mesothelioma the attributable risk was 88%.⁸ In some countries the pleural mesothelioma risk among women appears to be constant over time, suggesting that the incidence among women may be less dependent on occupational asbestos exposure.^2,5,8 It has also been suggested that the constant incidence among women implies that environmental exposure to asbestos is associated with a negligible risk⁵ or that the typical levels of environmental asbestos exposure will not exceed the threshold for mesothelioma risk.²Peritoneal mesothelioma is also linked to asbestos exposure, although with a much lower attributable risk than for pleural mesothelioma—that is, about 58% among men and less than 23% among women.⁸ Another study on elevated asbestos fibre contents in lung tissue concluded that 75% of peritoneal mesothelioma in men were most likely asbestos-related, whereas only 33% of the cases among women were attributed to asbestos exposure.⁹ It has been suggested that peritoneal mesotheliomas occur primarily among workers with higher cumulative exposures¹⁰ and that the risk increases more steeply at high exposures compared with pleural mesothelioma.^11,12 The participation of women in the industrial workforce was low, especially in occupations with high asbestos exposure such as insulators, miners and shipyard workers. Thus, a primary hypothesis would be that the peritoneal mesothelioma rates between men and women differ at least to the same extent as those for pleural mesothelioma.Trends in peritoneal mesothelioma among men and women are not as well described as trends for pleural mesothelioma. However, in the few countries with published data on trends, the annual incidence of peritoneal mesothelioma among women closely mirrors the pattern among men.^6,13,14 This surprising finding raises several important questions. First, is peritoneal mesothelioma in women the same disease as peritoneal mesothelioma among men? Second, do peritoneal mesothelioma and pleural mesothelioma differ between men and women with regard to asbestos exposure as a causal factor? The aims of this paper are to analyse differences in incidence rates of peritoneal mesothelioma in two countries and to evaluate time trends in incidence of peritoneal mesothelioma among men and women.     

The importance of scientific debate

Abstract

The authors monitored time trends in the incidences and distributions of malignant mesotheliomas during 1961–92 in 223 Israeli persons, including 21 men from a cohort of 3,057 asbestos-cement workers (83,122 person-years). The annual incidence rates of malignant mesotheliomas in Jewish men ranged between 2.5 per million in 1961–82 and 4.6 per million in 1985–92. The male-to-female incidence ratio rose from 1.2 in the 1960s to 2.9 during 1985–92, as a result of increases in risk among Israeli-born males. Females accounted for 37.6% of all cases, after exclusion of the cohort of asbestos workers. Of the 223 cases, 202 (91 %) had no indication of direct occupational exposure to asbestos. In Jewish females, the. incidence of malignant mesotheliomas did not increase after 1961. The mean age at diagnosis in all cases was lowest in the Israeli-born (53.0 years). High levels of asbestos exposure in the 1970s and the relatively early age of onset of the disease indicate that exposure began at a younger age in Israel than in European countries. Asbestos manufacture and use peaked in Israel during the mid-1970s, so the maximum impact of these trends has yet to be seen.     

Global magnitude of reported and unreported mesothelioma

Background

Little is known about the global magnitude of mesothelioma. In particular, many developing countries, including some with extensive historical use of asbestos, do not report mesothelioma.

Objectives

We estimated the global magnitude of mesothelioma accounting for reported and unreported cases.

Methods

For all countries with available data on mesothelioma frequency and asbestos use (n = 56), we calculated the 15-year cumulative number of mesotheliomas during 1994–2008 from data available for fewer years and assessed its relationship with levels of cumulative asbestos use during 1920–1970. We used this relationship to predict the number of unreported mesotheliomas in countries for which no information on mesothelioma is available but which have recorded asbestos use (n = 33).

Results

Within the group of 56 countries with data on mesothelioma occurrence and asbestos use, the 15-year cumulative number of mesothelioma was approximately 174,300. There was a statistically significant positive linear relation between the log-transformed national cumulative mesothelioma numbers and the log-transformed cumulative asbestos use (adjusted R² = 0.83, p < 0.0001). Extrapolated to the group of 33 countries without reported mesothelioma, a total of approximately 38,900 (95% confidence interval, 36,700–41,100) mesothelioma cases were estimated to have occurred in the 15-year period (1994–2008).

Conclusions

We estimate conservatively that, globally, one mesothelioma case has been overlooked for every four to five reported cases. Because our estimation is based on asbestos use until 1970, the many countries that increased asbestos use since then should anticipate a higher disease burden in the immediate decades ahead.     

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.     

Case report: peritoneal mesothelioma from asbestos in hairdryers

Background:

The relationship between mesothelioma and exposure to asbestos is well established. As a result, the use of asbestos in buildings, construction sites, and mines, as well as the implications of disease for the workers has received considerable attention. However, asbestos was also used in household equipment and consumer products, including hairdryers.

Purpose:

To examine one case of peritoneal mesothelioma in a hairdresser and review the relevant literature on asbestos exposure from hairdryers.

Methods:

The subject’s medical and occupational records were obtained and reviewed and a physical examination was performed.

Results:

The results indicate that the subject developed peritoneal mesothelioma from her occupational exposure to asbestos containing hairdryers in accordance with the literature.

Conclusion:

Hairdryers are possible sources of asbestos exposure in patients with mesothelioma, and the asbestos exposure risk is higher for those who use hairdryers occupationally.     

The incidence of malignant mesothelioma (1977-1996) and asbestos exposure in the population of an area neighboring Lake Iseo, northern Italy

The study was stimulated by the occurrence of malignant mesotheliomas among the workers of two adjacent factories located in Sarnico, near Lake Iseo (province of Brescia, northern Italy), one of which manufactured crocidolite and chrysotile ropes and gaskets until 1993. The aim of the study was: identification of malignant mesotheliomas occurring between 1977 and 1996 among the residents of 11 villages, which constituted the recruitment area of the work-force; estimation of the incidence of malignant pleural mesothelioma; collection of working histories of all cases to evaluate previous exposure to asbestos and radiation therapy. 21 cases of mesothelioma were detected (20 pleural, 1 peritoneal; 9 among males), and 20 were supported by histopathologic diagnosis. The incidence (x 100,000 person-years, standard: European population) was 2.5 (0.7-4.2) and 2.8 (1.2-4.3) among males and females, respectively, corresponding to a three-fold increase among males and a more than ten fold increase among women in comparison with the incidence reported by the Lombardy Cancer Registry. No cases had been exposed to radiation therapy, whereas all cases had been occupationally exposed to asbestos. Occupational exposure to asbestos had occurred in work on the production of crocidolite and chrysotile ropes and gaskets (6 males); in work in a textile factory producing cotton garments that was adjacent to and polluted by the former, where, in addition, chrysotile blankets were used for fireproofing in the weaving area and pipes were insulated using amosite-containing materials (10 cases, 6 among females); 5 cases occurred among women working in silk factories, where asbestos exposure was possible because of the presence of pipes insulated with asbestos and because women were handling temperature-controlled trays insulted with asbestos. In conclusion, the study demonstrated that the occurrence of mesothelioma was higher among females than males in the study area and that all cases of mesotheliomas had been occupationally exposed to asbestos.     

Epidemiology of mesothelioma of the pericardium and tunica vaginalis testis

PurposeMalignant mesothelioma most commonly arises in the pleura and peritoneum but also occurs rarely at other anatomical sites with mesothelial tissue, namely, the pericardium and tunica vaginalis testis (TVT). This review provides a better understanding of the epidemiology of mesothelioma of these extrapleural sites.MethodsWe conducted a systematic review of the epidemiologic and clinical literature on pericardial mesothelioma and mesothelioma of the TVT. We also analyzed U.S. Surveillance, Epidemiology, and End Results cancer registry data to describe incidence patterns of these malignancies.ResultsAn etiologic role of asbestos exposure has been hypothesized for pericardial and TVT mesotheliomas, but no analytical case-control epidemiologic studies exist to test this relationship. A substantial proportion of cases with these malignancies report no known asbestos exposure. In large occupational cohorts with heavy asbestos exposures, no cases of pericardial or TVT mesothelioma have been reported. Trends in the incidence of these malignancies do not match those of pleural mesothelioma, which correspond to historical trends of commercial asbestos use. A male preponderance of pericardial mesothelioma is not evident.ConclusionsIn the absence of analytic epidemiologic studies, the etiologic role of environmental risk factors for mesothelioma of the pericardium and TVT remains elusive.     

Non-malignant chest x ray changes in patients with mesothelioma in a large cohort of asbestos insulation workers.

To assess the prevalence of non-malignant chest x ray abnormalities in cases of mesothelioma 184 cases of mesothelioma (72 pleural and 112 peritoneal) which had occurred in a cohort of asbestos insulation workers followed up since 1967 were studied. Chest x ray films of satisfactory quality, on which the presence or absence of non-malignant radiological changes indicating interstitial pulmonary fibrosis or pleural fibrosis or both, could be assessed with a high degree of certainty were available. In some cases (20% for pleural mesothelioma, 11.6% for peritoneal mesothelioma) non-malignant radiological changes were not radiologically detectable. Parenchymal interstitial fibrosis (small irregular opacities) only was found in a proportion of cases (25.4% of pleural mesotheliomas, 12.5% of peritoneal mesotheliomas). Pleural fibrosis only was detected in 17% of cases of pleural mesothelioma and 27% of cases of peritoneal mesothelioma. Most patients had both parenchymal and pleural fibrosis. Although these results tend to indicate that in peritoneal mesothelioma the proportion of pleural fibrosis is significantly higher, these findings might have been due to the fact that in most cases of pleural mesothelioma non-malignant changes were interpreted in one hemithorax only. In 46 cases (21 pleural, 25 peritoneal) in which sufficient lung tissue was available histopathology of lung parenchyma indicated the presence of interstitial fibrosis; in 20 (43.5%) of these the chest x ray film had been read as negative. Thus the absence of radiologically detectable small opacities on the chest x ray film does not exclude the existence of interstitial pulmonary fibrosis in cases of mesothelioma among insulation workers. With lower levels of exposure (such as in family contacts of asbestos workers) it is conceivable that mesothelioma might occur in the absence of interstitial pulmonary fibrosis.     

Pleural malignant mesothelioma in Tuscany, Italy (1970-1988): II. Identification of occupational exposure to asbestos.

Following the finding of an unexpected cluster of mesotheliomas in textile workers, a surveillance system of malignant mesotheliomas was implemented in the region of Tuscany, Italy. This article reports on the investigation of 124 cases of mesothelioma diagnosed and reviewed by the Institutes of Morbid Anatomy and Histopathology at the Universities of Florence, Pisa, and Siena between 1970 and 1988. A complete occupational and asbestos exposure history was assessed through a semi-structured questionnaire directly administered to resident cases of Tuscany or, if deceased, to their closest living relatives, for a total of 100 interviews. The hypothesis of past occupational asbestos exposure was verified and documented. Seventy-two cases have been classified as occupationally exposed to asbestos; four were classified in the category of "possible domestic" exposure to asbestos. For two others, the role of other risk factors was stressed, and for 22 cases, either no asbestos exposure was found or the available data were not adequate to define it. The present study allowed identification of some unknown or scarcely known occupational asbestos exposures in the study area.     

Non-malignant chest x ray changes in patients with mesothelioma in a large cohort of asbestos insulation workers

To assess the prevalence of non-malignant chest x ray abnormalities in cases of mesothelioma 184 cases of mesothelioma (72 pleural and 112 peritoneal) which had occurred in a cohort of asbestos insulation workers followed up since 1967 were studied. Chest x ray films of satisfactory quality, on which the presence or absence of non-malignant radiological changes indicating interstitial pulmonary fibrosis or pleural fibrosis or both, could be assessed with a high degree of certainty were available. In some cases (20% for pleural mesothelioma, 11.6% for peritoneal mesothelioma) non-malignant radiological changes were not radiologically detectable. Parenchymal interstitial fibrosis (small irregular opacities) only was found in a proportion of cases (25.4% of pleural mesotheliomas, 12.5% of peritoneal mesotheliomas). Pleural fibrosis only was detected in 17% of cases of pleural mesothelioma and 27% of cases of peritoneal mesothelioma. Most patients had both parenchymal and pleural fibrosis. Although these results tend to indicate that in peritoneal mesothelioma the proportion of pleural fibrosis is significantly higher, these findings might have been due to the fact that in most cases of pleural mesothelioma non-malignant changes were interpreted in one hemithorax only. In 46 cases (21 pleural, 25 peritoneal) in which sufficient lung tissue was available histopathology of lung parenchyma indicated the presence of interstitial fibrosis; in 20 (43.5%) of these the chest x ray film had been read as negative. Thus the absence of radiologically detectable small opacities on the chest x ray film does not exclude the existence of interstitial pulmonary fibrosis in cases of mesothelioma among insulation workers. With lower levels of exposure (such as in family contacts of asbestos workers) it is conceivable that mesothelioma might occur in the absence of interstitial pulmonary fibrosis.     

Association between asbestos exposure and pericardial and tunica vaginalis testis malignant mesothelioma: a case–control study and epidemiological remarks

Objectives:The purposes of this study are to describe the epidemiology of pericardial and tunica vaginalis testis mesothelioma and assess the role of asbestos exposure for these rare diseases.Methods:Based on incident pericardial and tunica vaginalis testis mesothelioma cases collected from the Italian national mesothelioma registry (ReNaM) in the period 1993–2015, incidence rates, survival median period and prognostic factors have been evaluated. A case–control study has been performed to analyze the association with asbestos exposure (occupational and non-occupational) for these diseases.Results:Between 1993 and 2015, 58 pericardial (20 women and 38 men) and 80 tunica vaginalis testis mesothelioma cases have been registered with a mean annual standardized (world standard population as reference) incidence rates of 0.049 (per million) in men and 0.023 in women for the pericardial site, and 0.095 for tunica vaginalis testis mesothelioma. Occupational exposure to asbestos was significantly associated with the risk of the diseases [odds ratio (OR) 3.68, 95% confidence interval (CI) 1.85–7.31 and OR 3.42, 95% CI 1.93–6.04 in pericardial and tunica vaginalis testis mesothelioma, respectively]. The median survival was 2.5 months for pericardial and 33.0 months for tunica vaginalis testis mesotheliomas. Age was the main predictive factor for survival for both anatomical sites.Conclusions:For the first time in an analytical study, asbestos exposure was associated with pericardial and tunica vaginalis testis mesothelioma risk, supporting the causal role of asbestos for all anatomical sites. The extreme rarity of the diseases, the poor survival and the prognostic role of age have been confirmed based on population and nationwide mesothelioma registry data.     

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.     

Diffuse malignant pleural mesothelioma in an urban hospital: clinical spectrum and trend in incidence over time

This retrospective analysis reviews the clinical experience of a major urban referral hospital with diffuse malignant pleural mesothelioma during the 14-year period from 1973 through 1986. Seventy-five cases of definite or equivocal mesothelioma were identified. There were four cases of primary malignant peritoneal mesothelioma, seven cases of benign fibrous mesothelioma, and 64 cases of diffuse malignant pleural mesothelioma. In 43 cases (67%) of diffuse malignant pleural mesothelioma, there was historic evidence of asbestos exposure. In 21 cases (33%), there was no known history of asbestos exposure. An increase in annual incidence of diffuse malignant pleural mesothelioma was observed over the study period, from three cases in 1973 to ten cases in 1986. Despite greater awareness of this disease, the diagnosis remains a difficult one to establish given the nonspecific symptoms, signs and radiographic appearance, variable histologic appearance, and poor diagnostic sensitivity and specificity of thoracentesis and closed pleural biopsy. Thoracotomy, thoracoscopy, and CT-guided needle biopsies gave higher yields and are the diagnostic measures of choice when diffuse malignant pleural mesothelioma is suspected.     

Malignant mesothelioma and duration of asbestos exposure: Correlation with tissue mineral fibre content

Among 441 cases of malignant mesothelioma in the author's files, there were 324 for whom reliable information was available regarding the duration of exposure to asbestos. Included were 298 pleural and 26 peritoneal mesotheliomas. The mean duration of exposure to asbestos was 23 ± 14 years for all cases, and was not different for the pleural and peritoneal groups. Lung tissue was available for analysis of mineral fibre content in 94 cases. Linear regression analysis showed a significant correlation between duration of exposure and asbestos bodies per gramme of wet lung as determined by light microscopy, and between duration of exposure and total uncoated fibres (5 μm or greater in length) as well as commercial amphibole fibres per gramme as determined by scanning electron microscopy (P < 0.05). Individuals with direct exposures had on average higher asbestos contents than patients with indirect exposures. Furthermore, for each duration of exposure, shipyard workers had on average higher asbestos contents than non-shipyard workers (P < 0.05). Mesotheliomas are associated with a wide range of durations of exposure to asbestos and pulmonary asbestos burdens, and there is a rough correlation between duration of exposure and pulmonary commercial amphibole content.     

Malignant mesothelioma induced in baboons by inhalation of amosite asbestos

Ten out of 12 South African baboons (Papio ursinus) survived exposure to amosite asbestos dust for periods ranging from 242 days to 898 days at an aerosol level ranging between 1,100 and 1,200 fibers per milliliter. After exposure, they were kept under observation until they died; the total residence time of amosite varied from 1.2–10.2 years. All underwent detailed postmortem necropsy examinations. All baboons had asbestosis. Five of the baboons developed malignant diffuse mesothelioma; three peritoneal, and two pleural with peritoneal invasion. These results indicate that amosite is highly carcinogenic. Since it is difficult to accomplish follow-up of persons exposed to amosite asbestos because of the geographic location of the amosite mines and mills in South Africa (a majority of the workers being migrant laborers from countries bordering on the Transvaal), it is therefore probable that cases of peritoneal mesothelioma have been missed. If human beings are likely to react to amosite as do baboons, epidemiological follow-up should include identification of abdominal as well as thoracic neoplasms. © 1993 Wiley-Liss, Inc.     

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.     

High incidence of mesothelioma in an English city without heavy industrial use of asbestos

BACKGROUND: Mesothelioma rates are increasing in the industrialized world, related to occupational asbestos exposure. The highest rates have been reported from areas with specific industries such as shipbuilding or mining. Lower rates have been reported from areas without such industries. We studied an area without heavy industry to examine if such a pattern occurred in England. METHODS: We studied the population of Exeter Primary Care Trust, Devon, United Kingdom, with a population of 131,849. Exeter has no mining, shipbuilding or other heavy industry. All lung cancers and mesotheliomas were identified from the local cancer registry, supplemented by searches at all primary care practices. The cancer diagnoses were checked by inspection of histology or primary care records. Occupational data were extracted from the primary care records. RESULTS: The searches revealed 291 lung cancers, 283 of which had either histological proof or strong clinical evidence for the diagnosis. Twenty-two (8 per cent) of these were pleural mesotheliomas, 17 of these occurring in men. The incidence rate of mesothelioma in men over 40 years was 12.1 per 100,000 per year (95 per cent confidence intervals 7.0-19.3), one of the highest reported rates in the world. CONCLUSION: The mesothelioma epidemic will extend to areas without local heavy industrial exposure.