Death certificates in epidemiological studies, including occupational hazards: inaccuracies in occupational categories.

We compared death certificates for asbestos-associated diseases (mesothelioma, lung cancer, asbestosis) in two asbestos workers' cohorts. One (insulation workers) had current or recent employment and a strong, continuing union support system which gave them much information about the effects of asbestos exposure. The second cohort, asbestos factory workers, had no such advantage. The factory had closed almost 30 years before, and its workers had dispersed into many areas of the state and nation. Accuracy of medical diagnosis was comparable in the two groups, but occupational listings were not. Three-quarters of the insulators' death certificates told of asbestos work, while virtually none of the factory workers' certificates provided such information, even for deaths of mesothelioma and asbestosis. The data indicate that disease categories, based on medical and pathological diagnoses, at least for asbestos-associated disease, tend to be accurate. Attempts to identify groups at risk by sorting occupational categories can give variable results, good for those with current exposures, much less satisfactory for those with long-past occupational exposures.     

Estimation of future mortality from pleural malignant mesothelioma in Japan based on an age-cohort model

BACKGROUND: Japanese consumption of asbestos increased rapidly after the 1950s and lingered at a high level while the world's consumption decreased substantially after the 1980s. Mesothelioma is due primarily to asbestos, and the number of deaths in Japan is expected to increase in the future. METHOD: We estimated the future number of pleural mesothelioma deaths among males in Japan using an age-cohort model. RESULTS: Analyses showed that there would be about 100,000 deaths in Japan due to pleural mesothelioma in the next 40 years. Compared with the statistics in European countries, the ratio of expected death numbers to the population size is remarkably close to linear. The data-point for Japan was slightly lower than that which could be expected from the linear relationship. CONCLUSIONS: The limited availability of data may result in underestimation. Taking into consideration the consumption pattern of asbestos in recent decades, the incorporation of later cohorts will improve the estimation.     

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.     

A baseline profile of asbestos in the US-affiliated Pacific Islands

Asbestos is a recognized occupational and environmental hazard in the Asia-Pacific region, yet information regarding asbestos consumption, exposure, and asbestos-related diseases in the US-affiliated Pacific Islands (USAPIs) is scarce, and the situation regarding asbestos in these islands, particularly with regard to disease burden, surveillance, and health care capacity, is not well understood. Searching through scientific and "gray" literature and interviews with local cancer registry personnel and health professionals yielded no published data, only sufficient, indirect evidence of past and ongoing asbestos exposure, documented cases of mesothelioma and asbestosis, and minimal capacity for preventing and recognizing asbestos-related illnesses. Capacity and resource limitations within the USAPIs can impede regional progress in asbestos prevention and highlight the need for an integrated regional approach to address these data and capacity gaps. A regional mechanism to share expertise and resources and facilitate technical assistance to the USAPIs is urgently needed.     

The hazards of chrysotile asbestos: a critical review.

Chrysotile, or "white", asbestos is the dominant form of asbestos in international commerce today. It accounts for 99% of current world asbestos production of 2 million tonnes. Chrysotile is an extremely hazardous material. Clinical and epidemiologic studies have established incontrovertibly that chrysotile causes cancer of the lung, malignant mesothelioma of the pleura and peritoneum, cancer of the larynx and certain gastrointestinal cancers. Chrysotile also causes asbestosis, a progressive fibrous disease of the lungs. Risk of these diseases increases with cumulative lifetime exposure to chrysotile and rises also with increasing time interval (latency) since first exposure. Comparative analyses have established that chrysotile is 2 to 4 times less potent than crocidolite asbestos in its ability to cause malignant mesothelioma, but of equal potency of causation of lung cancer. The International Agency for Research on Cancer of the World Health Organization has declared chrysotile asbestos a proven human carcinogen. Sales of chrysotile asbestos have virtually ended in Western Europe and North America, because of widespread recognition of its health hazards. However, asbestos sales remain strong in Japan, across Asia and in developing nations worldwide. The claim has been made that chrysotile asbestos can be used "safely" under "certain conditions" in those nations. That claim is not accurate. The Collegium Ramazzini, an international learned society in environmental and occupational medicine, has called for an immediate worldwide ban on all sales and uses of all forms of asbestos, including chrysotile. The rationale for this ban is threefold: (1) that safer substitute materials are readily available, (2) that "controlled" use of asbestos is not possible, and (3) that the health risks of asbestos are not acceptable in either the industrialized or the newly industrializing nations.     

Altered functions of alveolar macrophages and NK cells involved in asbestos-related diseases

Asbestos exposure causes asbestosis and malignant mesothelioma, disorders which remain difficult to cure. We focused on alveolar macrophages (AM) and natural killer (NK) cells in asbestosis and mesothelioma, respectively, and examined their functions upon exposure to asbestos or in patients with mesothelioma. Exposure to asbestos caused rat AM to exhibit high production of transforming growth factor-beta (TGF-β) with prolonged survival in the absence of other cells, not simultaneously with the apoptosis caused by asbestos. The NK cell line showed impaired cytotoxicity with altered expression of activating receptors upon exposure to asbestos, and primary NK cells in culture with asbestos and peripheral blood NK cells in mesothelioma shared a decrease in expression of NKp46, a representative activating receptor. The AM finding indicates that AM contribute to asbestosis by playing a direct role in the fibrogenic response, as well as the inflammatory response. The response of NK cells indicates that exposure to asbestos has an immune-suppressive effect, as well as a tumorigenic effect. Our studies therefore reveal novel effects of asbestos exposure on AM and tumor immunity, which may represent valuable information for construction of a strategy for prevention and cure of asbestosis and malignant mesothelioma.     

Banning asbestos in Asia: campaigns and strategies by the Asian Network for the Rights of Occupational Accident Victims (ANROAV)

China, India, Indonesia, and Thailand are among the largest consumers of asbestos. Because markets in the West are dwindling, asbestos is heavily promoted in Asia. In spite of widespread usage, asbestos-related diseases are surprisingly few and reported cases of mesothelioma are rare in Asia except in Japan, Korea, and Singapore. The problem lies in diagnosis. Most of the asbestos-related diseases are not diagnosed in Asia and thus do not appear in government statistics. This deadly substance is killing workers. Unless drastic action is taken to stop its use, Asian workers as well as the general population will pay a heavy price.     

A baseline profile of asbestos in the US-affiliated Pacific islands

Abstract

Asbestos is a recognized occupational and environmental hazard in the Asia-Pacific region, yet information regarding asbestos consumption, exposure, and asbestos-related diseases in the US-affiliated Pacific Islands (USAPIs) is scarce, and the situation regarding asbestos in these islands, particularly with regard to disease burden, surveillance, and health care capacity, is not well understood. Searching through scientific and “gray” literature and interviews with local cancer registry personnel and health professionals yielded no published data, only sufficient, indirect evidence of past and ongoing asbestos exposure, documented cases of mesothelioma and asbestosis, and minimal capacity for preventing and recognizing asbestos-related illnesses. Capacity and resource limitations within the USAPIs can impede regional progress in asbestos prevention and highlight the need for an integrated regional approach to address these data and capacity gaps. A regional mechanism to share expertise and resources and facilitate technical assistance to the USAPIs is urgently needed.     

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.     

Banning Asbestos in Asia: Campaigns and Strategies by the Asian Network for the Rights of Occupational Accident Victims (ANROAV)

Abstract

China, India, Indonesia, and Thailand are among the largest consumers of asbestos. Because markets in the West are dwindling, asbestos is heavily promoted in Asia. In spite of widespread usage, asbestos-related diseases are surprisingly few and reported cases of mesothelioma are rare in Asia except in Japan, Korea, and Singapore. The problem lies in diagnosis. Most of the asbestos-related diseases are not diagnosed in Asia and thus do not appear in government statistics. This deadly substance is killing workers. Unless drastic action is taken to stop its use, Asian workers as well as he general population will pay a heavy price.     

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.     

Evidence-Based Decision-Making on Medical Technologies in China, Japan, and Singapore

Objective:  To review the use of evidence in the market approval process, reimbursement, and price control mechanisms for medicines and medical devices in China, Japan, and Singapore.
Methodology:  Documentary reviews relevant to public health policy and management by government authorities.
Results:  Drug regulatory authorities play a vital role in the market authorization process of medical technologies. The approval criteria in the three countries are similar to those of the US Food and Drug Administration and many other countries, whose core measures are efficacy, safety, and quality, along with risk-based analyses in China and Singapore. All established the national drug list (Japan) or lists (China and Singapore) for reimbursement. Although Japan reimburses any drugs listed, China and Singapore selectively reimburse regarding the types of the list. The cost-effectiveness is utilized for prioritization of new drugs listed in Singapore. Japan controls the price by government, whereas Singapore keeps market liberalism, and China maintains a mixture of both.
Conclusion:  All three countries have established their own mechanisms, but cost-effectiveness requirements have not been fully introduced yet, partially applied to the reimbursement processes in Singapore.     

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.     

Three decades of pleural cancer and mesothelioma registration in Austria where asbestos cement was invented

Recently, a new mesothelioma epidemic was predicted from observations made in Western Europe. From early observations in Austria the lower increase in cases of mesothelioma compared with neighbor countries had been related to different uses of asbestos. In order to test this hypothesis, incidence and mortality of pleural cancer [International Classification of Diseases (ICD)-8/9 163] were analyzed for three decades and supplemented by data from a cohort study in the factory that had been the largest consumer of asbestos imported to Austria and from all Austrian occupational diseases registered between 1990 and 2001. In men, mortality rates (based on 15 to 45 deaths/year) were lowest in 1980-1989, but similar in 1970-1979 and 1990-2001. No increase in younger-birth cohorts was detected. Incidence rates (based on 13 to 44 cases/year) increased (36%) non-significantly ( P=0.14). In women, a significant decrease in mortality and incidence rates ( P<0.01) was observed from 1970. Rates from work-related mesothelioma (based on only 0-7 men and 0-4 women/year) must be interpreted with caution. In the cohort of 2,816 asbestos cement workers 26 pleural mesotheliomas were registered from 1990 through mid-1999. Six of these cases (three male and three female) had not been registered as an occupational disease, but all of these cases had been encoded under ICD 163 in mortality statistics. One female cohort member registered as having asbestosis according to the death certificate had died from mesothelioma according to the statistics of occupational diseases. We conclude that no epidemic of mesothelioma due to past asbestos exposure is to be expected in Austria.     

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.     

An expert system for the evaluation of historical asbestos exposure as diagnostic criterion in asbestos-related diseases

Compensation schemes for asbestos-related diseases have developed different strategies for attributing a specific disease to occupational exposure to asbestos in the past. In the absence of quantitative exposure information that allows a valid estimate of an individual's historical exposure, general guidelines are required to retrospectively evaluate asbestos exposure. A risk matrix has been developed that contains qualitative information on the proportion of workers exposed and the level of exposure in particular industries over time. Based on this risk matrix, stepwise decision trees were formulated for decisions regarding the decisive role of historical asbestos exposure in case ascertainment of asbestosis and mesothelioma. Application of decision schemes will serve to speed up the process of verifying compensation claims and also contribute to a uniform decision-making process in legal procedures.     

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 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.     

An updated review on asbestos and related diseases in China

Abstract

Background: Asbestos is an industrial mineral that can cause diseases such as asbestosis, lung cancer, and mesothelioma. Asbestos consumption in China has increased steadily since the 1960s and is currently at half a million tonnes per year. Work conditions in the asbestos-related industries are poor and exposure levels frequently exceed the occupational exposure limit.

Objective: To provide an updated overview on asbestos production and consumption in China and discuss what is known about the resulting burden of asbestos-related diseases.

Findings: China is the world's top chrysotile consumer and second largest producer. Over a million people may be occupationally exposed, yet reliable disease statistics are unavailable and the national burden of asbestos-related disease (ARD) is not well known. Nevertheless, ARD prevalence, incidence, and mortality are expected to be high and will increase for many decades due to the volume of asbestos consumed historically, and a long latency period.

Conclusions: Government policies to prevent ARD have been implemented but more actions are necessary to ensure compliance and ultimately, the complete elimination of asbestos to prevent a heavy future disease burden.     

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.