Railways and asbestos in Japan (1928-1987)--epidemiology of pleural plaques, malignancies and pneumoconioses-.

Asbestos has been an indispensable insulating material for railway industries, especially steam locomotives (SLs). This review (1928-1987) consists of three parts. 1) Pleural plaques: Since the 1970s, pleural plaques have been regarded as evidence of past asbestos inhalation, and more recently recognized as a risk factor of asbestos-related malignancies. For diagnostic criteria on plain radiographs, the modified ILO 1980 International Classification of Radiographs of Pneumoconioses was used. Most cases had pleural plaques with normal lungs. Large plant workers showed a significantly higher rate of plaques than workers in smaller plants. Bilateral plaques were dominant followed by the left, then the right lung, and chest wall plaques were dominant over the diaphragm. The manifestation of pleural plaques was more correlated to years since the onset of the asbestos exposure than the sum of asbestos work years, although the result was not significant. The boilermen of railway ferry steamers had a significantly higher plaque rate than other seamen. CT studies on plaques started in 1978. 2) Asbestos-related malignancies: Five retrospective cohort studies 1960-1970 were made on primary lung cancer incidence and mortality among 350,000 active railway men with smoking information. The follow-up period was 20 yr at the longest. Almost all plant workers showed a tendency of higher incidence or mortality than the controls. Two cases of mesothelioma were reported in 1980. 3) Pneumoconioses: Most studies (1928-1975) had relatively low prevalence rates among SL-related workers.

Sarcoidosis and tuberculosis: epidemiological similarities and dissimilarities. A review of a series of studies in a Japanese work population (1941-1996) and the general population (1959-1984).

AIM: The aim of this review is to discuss the epidemiological relationship between sarcoidosis and tuberculosis. METHODS: We have used a series of health surveillance data in a Japanese work population of 460,000 employees including 70,000 working in Tokyo (1941-1996) and the data from a nation-wide sarcoidosis survey in the general population (1959-1991). The work population was annually x-rayed and tuberculin tested. The data of primary tuberculosis were obtained from a 17 year cohort study of tuberculin positive converters and primary pulmonary sarcoidosis data from the registry of the disease (1952-1996) in the same work population. Hilar lymphadenopathy (HL) was observed as a common marker of the two diseases. RESULTS: 1) Sarcoidosis HL was not detected in the work population until tuberculosis HL decreased. 2) BHL was rare in primary tuberculosis, but occurred in 95.5% of sarcoidosis subjects. 3) In both diseases, HL resolved in a few years, though accompanying extra-pulmonary involvements delayed the resolution of sarcoidosis BHL. 4) The grade of tuberculin sensitivity prior to sarcoidosis was not a risk factor for developing sarcoidosis. 5) Several well-documented sarcoidosis cases remained tuberculin-negative before and at the time of diagnosis of the disease and after resolution of pulmonary involvement. 6) Age-specific incidence curves showed a mono-modal curve in tuberculosis and a bimodal curve in sarcoidosis. 7) Tuberculosis prevalence was higher in the South of Japan, while sarcoidosis was higher in the North. CONCLUSIONS: These epidemiological dissimilarities do not support a tuberculosis etiology of sarcoidosis.

Epidemiology of sarcoidosis: new frontiers to explore.

Epidemiologic studies have been playing frontier roles to explore determinants of sarcoidosis by observing affected persons with the related population. Since 1990, more than 100 epidemiologic papers have been added to the Medline and PubMed databases. Of them, just a few were dated after March 2001. This article is focused on the papers after that time, referring to a number of previous important epidemiologic studies. The review is arranged according to two major epidemiologic categories: (1) host-related findings such as age, sex, race, familial clustering, and lifestyle; and also (2) time- and space-related findings such as exposures, geographical variation, local clustering, climate and seasonal variation, migration, and time-space clustering (transmission).