Japanese workplace health management in pneumoconiosis prevention.

OBJECTIVE: The Japanese government established the Pneumoconiosis Law in 1960 to protect health and promote the welfare of workers engaged in dust-exposed works. This article describes Japanese practice in workplace health management as regulated by the Pneumoconiosis Law to reduce pneumoconiosis in Japan. METHODS: We collected information addressing pneumoconiosis and the health care of dust-exposed workers. We included all types of scientific papers found through a PubMed search as well as official reports, guidelines, and relevant laws published by the Ministry of Health, Labour and Welfare (MHLW) of Japan and other academic institutions. RESULTS: In the past, pneumoconiosis has been a major cause of mortality and morbidity for Japanese workers engaged in dust-exposed work. The Pneumoconiosis Law introduced a system of pneumoconiosis health examination and health supervision to protect workers' health. According to the periodic pneumoconiosis health examination reports in Japan, the prevalence of pneumoconiosis fell from the highest reported figure of 17.4% in 1982, where 265,720 examinations were conducted, to 1% in 2013 in which 243,740 workers were examined. The number of new cases of pneumoconiosis dropped from 6,842 cases in 1980 to 227 cases in 2013. One hundred and seventy two workers were diagnosed as having pneumoconiosis complications in 1980; however, the number fell to five in 2013. CONCLUSION: After reaching its peak in the 1980s, pneumoconiosis and its complications fell each year. The achievement of Japanese pneumoconiosis prevention can be credited to a comprehensive provision for worker health, regulated by a thorough legal framework.

Radiographic progression of silicosis among Japanese tunnel workers in Kochi.

OBJECTIVE: The aim of our study was to investigate the natural course of silicosis in terms of radiographic progression among Japanese tunnel workers. METHODS: Tunnel workers with silicosis were included in our study between January 2008 and June 2011. We retrospectively assessed workers' radiographs from their first through last visits to see whether there was progression. All films were interpreted by two physicians, who had been specially trained in using the ILO (2000) International Classification of Radiographs of Pneumoconioses (ILO/ICRP). We classified the radiographic findings according to the ILO/ICRP. Survival analysis was performed and then presented as time to progression. Subgroup analysis among the progressed group was performed to demonstrate duration of progression. RESULTS: A total of 65 patients, who were no longer exposed to silica for the duration of the study, were included. The mean age at the first visit was 58.60 ± 7.10 years. The incidence rate of progression was 42 per 1,000 person-years with a median time to progression of 17 years. Progression was demonstrated among 33 cases (51%). The mean durations of progression from category 1 to category 4 and category 2 to category 4 were 14.55 and 10.65 years, respectively. Most patients (86%) had radiographic change from category 1 or 2 directly to category 4. CONCLUSION: Silicosis progressed at a relatively high rate among tunnel workers without further silica exposure. The high probability of progression directly from category 1 to category 4 may lead to further investigation for the improvement of disease prevention.