Railways and Asbestos in Japan (1928–1987)—Epidemiology of Pleural Plaques, Malignancies and Pneumoconioses—

Abstract

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 asbestosrelated 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 had relatively low prevalence rates among SLrelated workers. (J Occup Health 2008; 50: 297-307)

Pleural Plaque Profiles on the Chest Radiographs and CT Scans of Asbestos-exposed Japanese Construction Workers

“…The CXR showed no lesions, while the chest CT scans demonstrated hyaline plaques in all 22 sites. These results are similar to those reported by Kishimoto et al 11) .…”

Pleural plaques and asbestosis: dose- and time-response relationships based on HRCT data

“…Unilateral pleural plaques were considered relevant only in the case of typical pleural features and, for the diagnosis of pulmonary asbestosis, a bilateral extent of the interstitial abnormalities was needed. This is in accordance with publications dealing with asbestos-related pleural abnormalities and with the weakness of the data about unilateral asbestosis [27,28]. After review, the same models were confirmed for pleural plaques, but were not significant for asbestosis due to an insufficient number of cases (data not shown).…”

Are pleural plaques an appropriate endpoint for risk analyses?

“…Numerous studies have examined the dose-or exposureresponse relation for pleural plaques (Bar-Shai et al, 2012;Boffetta, 1998;Clin et al, 2011;Eisenhawer et al, 2014;Ehrlich et al, 1992;Finkelstein & Vingilis, 1984;Hosoda et al, 2008;Jakobsson et al, 1995;Järvholm, 1992;Karjalainen et al, 1994;Lockey et al, 2015;Mastrangelo et al, 2009;McDonald et al, 1986;Moolgavkar et al, 2014;Paris et al, 2008Paris et al, , 2009Rohs et al, 2008;Sandén & Järvholm, 1986;Shepherd et al, 1997;Soulat et al, 1999;Van Cleemput et al, 2001). Results differ among these studies, 6 but exposure variables found relevant in one or more studies include time since first exposure (TSFE), age at first exposure (Jones, 1997), type (Hillerdal, 1997;Jones, 1997;Sandén & Järvholm, 1986) and dimensions of fiber (Hillerdal, 1997;Jones, 1997), lung fiber burden (Karjalainen et al, 1994;Roberts, 1971), duration of exposure, intensity of estimated asbestos exposure and cumulative exposure (measured in various ways).…”