Asbestos-related lung cancer and mesothelioma in Japan

In Japan, crocidolite had been used for asbestos cement pipe and spraying, and amosite had been used for building board and spraying. These two types of asbestos had stopped to use in Japan in the late 1970s. An extreme increase in imported asbestos (all 3 commercial types) was observed between 1960 and 1974. In 1960, 77,000 tons of asbestos were imported, and reached the peak as 352,316 tons in 1974. This extreme rise of asbestos imports corresponds with the recent rapid increase in mortality of malignant pleural mesothelioma. Between 1995 and 1999, an estimated mean annual death from pleural mesothelioma was about 500. The annual number of compensated occupational respiratory cancers due to asbestos exposure has also been increasing. Up to the end of March 2000, 162 cases with malignant mesothelioma and 197 cases with lung cancer were compensated. As for lung cancer, epidemiological studies are scanty in Japan. Limited environmental data of the working places in asbestos textile factories suggests that heavy asbestos exposure in the past made deaths from respiratory diseases. Less asbestos exposure will enable exposed workers to survive enough to reach cancer age. Even now smoking rate among males in Japan are over 50%. So lung cancer deaths caused by the interaction between smoking and asbestos exposure will be continuing.     

Lung cancer and mesothelioma in the pleura and peritoneum among Swedish insulation workers

OBJECTIVES: To estimate the risk of cancer and death in Swedish insulation workers some years after their exposure to asbestos had stopped. One hypothesis was that the risk of lung cancer would tend to decrease some years after the exposure had ended. METHODS: In a cohort study the cancer morbidity and cause of death was investigated in 248 insulation workers and compared with the corresponding morbidity and mortality in the general population. Due to stringent regulations, exposure to asbestos of all types had almost ended in Sweden in the mid- 1970s. Through a questionnaire, surviving insulation workers were asked about their exposure to asbestos and their smoking habits. RESULTS: Between 1970 and 1994 there were 86 deaths compared with the 46.0 expected (standardised incidence ratio (SIR) 1.9; 95% confidence interval (95% CI) 1.5 to 2.3), the increase was mainly due to an increased cancer mortality. The morbidity was increased for lung cancer (11 cases v 2.5 expected (SIR 4.4; 95% CI 2.2 to 7.9)), peritoneal mesothelioma (seven cases; no expected incidence could be calculated as the occurrence is too rare in the general population), cancer in pancreas (five cases v 0.7 expected (SIR 7.1; 95% CI 2.3 to 16.7)). No cases of pleural mesothelioma were found. The risk of lung cancer did not tend to approach that of the general population after the exposure to asbestos decreased. CONCLUSIONS: In the 1980s and the early 1990s, Swedish insulation workers still have a highly increased risk of diseases related to asbestos. The attributable risk for death and cancer was about 50%. The study also confirms the previous finding that mesothelioma in insulation workers seems to be situated in the peritoneum more often than in the pleura.     

Pleural mesothelioma: forecasts of the death toll in the area of Casale Monferrato,Italy

In the city of Casale Monferrato, the largest Italian factory that produced asbestos‐cement goods was active from 1907 to 1985. Consequently, asbestos fibers scattered in the surrounding area and caused an enormous number of cases of pleural mesothelioma. Owing to the very long latency of this disease, many subjects have not exhibited its symptoms yet. The aim of this paper is to model and predict the future evolution of the number of deaths due to this disease among residents in the area around that city. The model used here is based on a cellular automata that is assumed to pass through three steps: exposure, contamination, and diagnosis. In this way, forecasts of the future evolution take into account the environmental conditions that changed over the last century because of different levels of plant activity. The model is fitted to annual diagnosis data from 1954 to 2008. Results show that deaths will not end until 2031 and that in the next two decades, at least 505 more subjects will be diagnosed with this disease. Copyright © 2012 John Wiley & Sons, Ltd.     

A cohort study on mortality among wives of workers in the asbestos cement industry in Casale Monferrato, Italy.

The study investigates mortality from cancer and other diseases in a cohort of wives of asbestos cement workers in Casale Monferrato (northwest Italy). After the exclusion of women with an occupational record in the asbestos cement industry, the cohort comprised 1964 women. Their domestic exposure was estimated according to their husbands' periods of employment in the plant: 1740 had a period of domestic exposure whereas the remaining 224 married an asbestos cement worker only after he definitely stopped his activity in the asbestos cement plant; these have, therefore, been considered as unexposed. The cohort of wives was constructed entirely through official records in the town offices and is both exhaustive and unaffected by recall bias. At the end of follow up (1988) 1669 women were alive, 270 were dead and 25 (1.2%) were untraced. Main mortality analyses were only up to age 79 to reduce the misclassification of causes of death. Expected mortality was based on local rates. Mortality analyses were limited to the period 1965-88 due to the availability of local rates: in that period 210 deaths occurred among women with domestic exposure v 229.1 expected. There were four deaths from pleural tumours (one diagnosed as mesothelioma at necropsis) and six from lung cancer v. 0.5 and 4.0 expected respectively. Two further cases of mesothelioma were diagnosed by histological examination after the end of follow up. None of the three wives with histologically diagnosed mesothelioma had been engaged in industrial activities. Corresponding information for the other three cases could not be traced.     

Mortality from all cancers of asbestos factory workers in east London 1933-80

OBJECTIVE—To give the observed and expected deaths due to cancer at all separate sites in asbestos workers in east London, and to analyse these for overall effect and exposure-response trend.
METHODS—The mortality experience of a cohort of over 5000 men and women followed up for over 30 years since first exposure to asbestos has been extracted.
RESULTS—There was a large excess of deaths due to cancer (537 observed, 222 expected). Most of these were due to cancer of the lung (232 observed, 77 expected) and pleural (52) and peritoneal (48) mesothelioma. The exposure-response trend for all these three causes was highly significant. There was also an excess of cancer of the colon (27 observed, 15 expected) which was significantly related to exposure. There were significant excesses of cancer of the ovary, of the liver, and of the oesophagus but with no consistent relation to exposure.
CONCLUSIONS—The excess risk of cancer after exposure to asbestos was mainly due to cancer of the lung and mesothelioma. An exposure related excess of cancer of the colon was also detected but the possibility that some of these deaths may have been peritoneal mesotheliomas could not be excluded. There was no consistent evidence of exposure related excesses at any other site.


Keywords: asbestos; cancer; exposure-response     

Future trends of mesothelioma mortality in Japan based on a risk function

Mesothelioma is a malignancy with poor prognosis. It is chiefly caused by asbestos exposure and its symptoms can occur about 30-50 yr after the initial exposure. This study aims to predict the future trends in mesothelioma mortality in Japan using a method that is an alternative to the age-cohort model. Our approach is based on a risk function that links mesothelioma mortality combined with data pertaining to the population, size of the labor force, and quantity of asbestos imports. We projected the number of deaths occurring in individuals aged 50-89 for yr 2003-2050 using risk functions. Our results have indicated that mesothelioma mortality among Japanese people aged 50-89 yr will continue to increase until 2027 and reach a maximum of 66,327 deaths in the years 2003-2050. Our estimate has also suggested that the number of mesothelioma deaths could be significantly reduced if there were adequate compliance with the administrative level guidelines for occupational asbestos exposure.     

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.     

The Handling of Workmen’s Compensation Claims

Few data exist concerning the comparative neoplastic potential in man of the several kinds of asbestos. In particular, there has been no evidence concerning whether the amosite variety is carcinogenic. The matter is of practical importance, since amosite use in the United States has sharply increased. The mortality experience of a group of 230 men previously employed in an amosite asbestos factory was studied during the years 1960 through 1971. Total deaths were more than twice the number anticipated: 46.4 were expected, and 105 occurred. Some 14 deaths were due to asbestosis. Both lung cancer and mesothelioma were found in considerable excess. Two or three deaths from lung cancer were expected, and 25 occurred. There were five deaths from mesothelioma. Occupational exposure to amosite asbestos can be associated with serious cancer hazard; its continued industrial use requires rigorous control.     

Estimating the number of asbestos-related lung cancer deaths in Great Britain from 1980 to 2000

INTRODUCTION: Inhalation of asbestos fibres is known to cause two main kinds of cancer-mesothelioma and lung cancer. While the vast majority of mesothelioma cases are generally accepted as being caused by asbestos, the proportion of asbestos-related lung cancers is less clear and cannot be determined directly because cases are not clinically distinguishable from those due to other causes. The aim of this study was to estimate the number of asbestos-related lung cancers among males by modelling their relative lung cancer mortality among occupations within Great Britain in terms of smoking habits, mesothelioma mortality (as an index of asbestos exposure) and occupation type (as a proxy for socio-economic factors). METHODS: Proportional mortality ratios for lung cancer and mesothelioma for the 20-year period from 1980 to 2000 (excluding 1981) were calculated for occupational groups. Smoking indicators were developed from three General Household Surveys carried out during the 1980s and 1990s. Poisson regression models were used to estimate the number of asbestos-related lung cancers by estimating the number of lung cancer deaths in each occupation assuming no asbestos exposure and subtracting this from the actual predicted number of lung cancer deaths. RESULTS: The effect of asbestos exposure in predicting lung cancer mortality was weak in comparison to smoking habits and occupation type. The proportion of current smokers in occupational groups and average age at which they started smoking were particularly important factors. Our estimate of the number of asbestos-related lung cancers was between two-thirds and one death for every mesothelioma death: equivalent to between 11 500 and 16 500 deaths during the time period studied. CONCLUSIONS: Asbestos-related lung cancer is likely to have accounted for 2-3% of all lung cancer deaths among males in Great Britain over the last two decades of the 20th century. Asbestos-related lung cancers are likely to remain an important component of the total number of lung cancer deaths in the future as part of the legacy of past asbestos exposures in occupational settings.     

Mesothelioma in Great Britain in 1968-1983

The British mesothelioma register records deaths in Great Britain when the word "mesothelioma" is on the death certificate. In 1968-1983 the mesothelioma deaths among men increased from 114 to 467, while those among women increased from 38 to 90. In 1983 the crude mesothelioma death rates were 17.5 per million and 3.2 per million for the men and women, respectively. The Northern region had the highest crude rates. At the county level, the highest crude deaths rates in 1976-1983 were recorded for the men in Devon and for the women in Lancashire. Marked differences occurred in the ratio of deaths among men to deaths among women for mesothelioma of the pleura (4.6:1) and for mesothelioma of the peritoneum (2:1). The age-specific death rates for men and women diverged markedly for pleural mesothelioma but not for peritoneal mesothelioma. Trends in the use of asbestos and in age- and sex-specific death rates suggest that the annual number of mesothelioma deaths will continue to increase, possibly until the turn of the century. This increase will be concentrated among the men as the main asbestos exposure of women occurred during the war and the annual deaths due to this exposure may have already peaked.     

A mortality study among workers in an English asbestos factory.

The previous report on this cohort study of workers in an asbestos textile factory (Knox et al., 1968) showed little evidence of increased mortality among workers who had entered the factory after the implementation in 1932 of the first Asbestos Industry Regulation (1931) but observed that no firm conclusions could be drawn, as little carcinogenic effect would be expected for 20 years after first exposure. A further 8 1/2 years of follow-up has revealed some asbestos-related disease in this latter group, although very much less than for employees first exposed before 1933. Among the 963 workers first exposed in 1933 or later, mortality was increased for carcinoma of the bronchus (31 deaths; 19-3 expected for all lung cancers) and non-malignant respiratory disease (35 deaths, 25-0 expected), and a further 5 deaths were attributed to pleural mesothelioma.     

Indications of an increase of occupational pleural mesothelioma in Japan

In order to obtain an epidemiological picture of occupational pleural malignant mesotheliomas in Japan, the author surveyed the Annual of Pathological Autopsy Cases (published by the Japanese Pathological Society) from 1974 through 1980. Two hundred and twenty-two malignant mesotheliomas (0.114% of all autopsy cases) were found in that period. One hundred and forty-five cases (0.074%) of them were of pleural origin. Until 1977, there were no pleural malignant mesotheliomas associated with asbestosis, but there were one in 1978, three in 1979 and two in 1980. Two of them were housewives and the others were a ship builder, a welder, a ceramist and a steel factory worker. Two lived in Sakae City, and the others in Kure City, Kaizuka City, Nagasaki City and Kanagawa Prefecture, where large shipyards are located. Compared to the Western countries, there is a time lag of 10 to 20 years in the increase of consumption of asbestos in Japan, where the increase has occurred rapidly after World War II. The epidemiological picture obtained by this study clearly states that the number of occupational pleural malignant mesotheliomas began to increase in the past few years in Japan.     

Malignant pleural mesothelioma in parts of Japan in relationship to asbestos exposure

Malignant pleural mesothelioma is induced by asbestos exposure. Many reports have described this situation in America and European countries, but a few have been published in Japan. In this study malignant pleural mesothelioma cases in hospitals located in an area facing the Seto Inland Sea were evaluated. A total of 106 patients were examined with 100 patients having had occupational exposure to asbestos and 6 patients without such histories of asbestos exposure. Ninety seven were male and 9 were female. Ages ranged from 41 to 87 yr with mean of 64.8+/-5.3 yr. Thirty seven cases showed epithelial type of tumor, 25 biphasic type and 15 showed sarcomatous. The remaining 23 cases had insufficient evidence for typing the tumor. The mean survival rate for all cases was 9.2+/-11.6 months. Fifty-one patients had occupational histories of shipyard work, 16 patients worked in asbestos cement piping, and the remainder were employed in miscellaneous jobs related asbestos exposure. The duration of asbestos exposure ranged up to 20 yr or longer with the mean of 17.2+/-8.9 yr and the average latent period for the occurrence of malignant pleural mesothelioma was more than 31 yr with the mean of 37.0+/-13.3 yr. Quantification of asbestos bodies in the lungs indicated a high concentration in most patients and the major types of asbestos fibers were crocidolite and amosite. Six cases appeared after exposure to chrysotile. These results indicated that ninety four percent of malignant pleural mesothelioma appeared due to the exposure to asbestos including crocidolite and amosite. The remainder may be blamed on exposure to chrysotile.     

Occupational asbestos exposure and predictable asbestos-related diseases in India

BACKGROUND: India imports nearly 100,000 metric tons of asbestos per year, and small-scale asbestos (chrysotile and tremolite) mining and milling contributes nearly 5%-10% of the total national usage. The industry is relatively young, having started in the 1950s and 1960s. METHODS: Surveys of asbestos-exposed workers have identified significant occupational exposures, early pleural and parenchymal changes on chest radiograph, and decrements in lung function. RESULTS AND CONCLUSIONS: Based on knowledge of past and current exposures to asbestos in industry, we can predict a future occurrence of clinical asbestos-related diseases-pleural changes, pulmonary fibrosis, bronchogenic carcinoma, and diffuse malignant mesothelioma. These cases of asbestos related disease are expected to occur in asbestos exposed workers from mining, milling, and manufacturing as well as in those with secondary exposures to asbestos-containing materials, including construction and maintenance workers, users of asbestos-containing consumer products, and the occupants of asbestos-containing buildings.     

Differences in occupational mortality from pleural cancer, peritoneal cancer, and asbestosis.

OBJECTIVE--To assess whether the increased risk of disease related to asbestos in occupations from the construction and engineering industries applies equally to pleural cancer, peritoneal cancer, and asbestosis. METHODS--Analysis was based on deaths among men aged 20-74 in England and Wales during 1979-80 and 1982-90. (n = 1,656,096). Information about cause of death and the last full time occupation of decedents was derived from death certificates. Proportional mortality ratios (PMRs) by occupation were calculated for each of pleural cancer, peritoneal cancer, and asbestosis. RESULTS--Altogether, 2848 deaths were attributed to cancer of the pleura, 362 to cancer of the peritoneum, and 281 to asbestosis. When occupations were ranked according to PMRs from these diseases, striking differences were found. The category of construction workers which included laggers had the highest mortality from peritoneal cancer (PMR 990, 64 deaths), but a PMR of only 160 (77 deaths) for pleural cancer. In contrast, several occupations with much higher mortality from pleural tumours had no excess of peritoneal cancer. PMRs for asbestosis related more closely to those for peritoneal than pleural cancer. CONCLUSIONS--These findings suggest that the exposure-response relations for diseases related to asbestos are not all linear, and that risks of pleural mesothelioma may be underestimated by simple extrapolation from observations in cohorts with heavy exposure.     

Incidence of cancer among Norwegian boiler welders.

OBJECTIVES: The cancer incidence among 2957 boiler welders was investigated. The subjects were registered electrical welders from 1942 to 1981. A subcohort of 606 stainless steel welders was studied separately. METHODS: The investigation was a historical prospective cohort study based on a national registry. The loss of follow up was 4.9%. RESULTS: There were 625 deaths (659 expected). There were 269 cancer cases (264 expected). An excess of lung cancer was found; 50 cases v 37.5 expected. There were three cases of pleural mesotheliomas v 1.1 expected. The subcohort of stainless steel welders had six cases of lung cancer v 5.8 expected, and one case of pleural mesothelioma v 0.2 expected. CONCLUSIONS: The welders in the study were assumed to represent a qualified work force. These welders had a small excess risk of lung cancer. The excess risk did not seem to be associated with stainless steel welding. Smoking and asbestos exposure were potential confounders.     

An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy.

The mortality experience of a cohort of chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (hepatic cirrhosis, accidents). For mortality from cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for oral cancer (SMR 231 based on six deaths), cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for cancer of the larynx. Rates were not increased for lung, stomach, or any other type of cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for oral cancer, but the greatest risks for laryngeal and pleural cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to chrysotile asbestos (or to the fibre balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of laryngeal cancer and pleural mesothelioma. The absence of excess mortality from lung cancer in this cohort is difficult to interpret.     

An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy

The mortality experience of a cohort of chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (hepatic cirrhosis, accidents). For mortality from cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for oral cancer (SMR 231 based on six deaths), cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for cancer of the larynx. Rates were not increased for lung, stomach, or any other type of cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for oral cancer, but the greatest risks for laryngeal and pleural cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to chrysotile asbestos (or to the fibre balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of laryngeal cancer and pleural mesothelioma. The absence of excess mortality from lung cancer in this cohort is difficult to interpret.     

Clinical consequences of asbestos-related diffuse pleural thickening: A review

Asbestos-related diffuse pleural thickening (DPT), or extensive fibrosis of the visceral pleura secondary to asbestos exposure, is increasingly common due to the large number of workers previously exposed to asbestos. It may coexist with asbestos related pleural plaques but has a distinctly different pathology. The pathogenesis of this condition as distinct from pleural plaques is gradually becoming understood. Generation of reactive oxygen and nitrogen species, profibrotic cytokines and growth factors in response to asbestos is likely to play a role in the formation of a fibrinous intrapleural matrix. Benign asbestos related pleural effusions commonly antedate the development of diffuse pleural thickening. Environmental as well as occupational exposure to asbestos may also result in pleural fibrosis, particularly in geographic areas with naturally occurring asbestiform soil minerals. Pleural disorders may also occur after household exposure. High resolution computed tomography (CT) is more sensitive and specific than chest radiography for the diagnosis of diffuse pleural thickening, and several classification systems for asbestos-related disorders have been devised. Magnetic resonance imaging and fluorodeoxyglucose positron emission tomography (PET) scanning may be useful in distinguishing between DPT and malignant mesothelioma. DPT may be associated with symptoms such as dyspnoea and chest pain. It causes a restrictive defect on lung function and may rarely result in respiratory failure and death. Treatment is primarily supportive.     

Pleural mesothelioma in Sweden: an analysis of the incidence according to the use of asbestos

OBJECTIVE: To investigate if the preventive measures taken to reduce the occupational exposure to asbestos have resulted in a decreased incidence of pleural mesothelioma in Sweden. METHODS: The incidence of pleural mesothelioma between 1958 and 1995 for birth cohorts born between 1885 and 1964 was investigated. The cases of pleural mesothelioma were identified through the Swedish Cancer Register. RESULTS: In 1995, around 80 cases of pleural mesothelioma could be attributed to occupational exposure to asbestos. There is an increasing incidence in more recent birth cohorts in men. The incidence was considerably higher in the male cohort born between 1935 and 1944 than in men born earlier. CONCLUSIONS: The annual incidence of pleural mesothelioma attributable to occupational exposure to asbestos is today larger than all fatal occupational accidents in Sweden. The first asbestos regulation was adopted in 1964 and in the mid 1970s imports of raw asbestos decreased drastically. Yet there is no obvious indication that the preventive measures have decreased the risk of pleural mesothelioma. The long latency indicates that the effects of preventive measures in the 1970s could first be evaluated around 2005.