Japanese workplace health management in pneumoconiosis prevention

Abstract

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.

Fig. 1.

Schematic flowchart for performing pneumoconiosis pulmonary function assessment *Decision to perform secondary tests is made by examining physician based on the comprehensive assessment of pulmonary function test, radiographic findings, previous test results and other observations. Note: Feasibility of primary tests means whether subjects are eligible to perform spirometry or not. The Hugh-Jones breathlessness scale (also known as Fletcher-Hugh-Jones breathlessness scale in Japan) describes respiratory disability from none (Grade 1) to almost complete incapacity (Grade 5), in which Grade 3 represent moderate respiratory disability. The normal value for the PaO₂, irrespective of age, is greater than 80 Torr; PaO₂ value of less than 60 Torr is generally considered as severe hypoxemia. The A-aDO₂ for a subject at sea level and breathing room air is normally less than 10 Torr but the value increases with age. The reference A-aDO₂ limit values for Japanese population is provided by the Ministry of Health, Labour and Welfare of Japan.

Fig. 2.

Changes in the number of workers with pneumoconiosis and pneumoconiosis complications (A) Number of examined workers and pneumoconiosis prevalence between 1960 and 2013 (B) Number of workers with pneumoconiosis complication between 1980 and 2013 Note: Pneumoconiosis cases are classified as pneumoconiosis supervision class II or higher. Pneumoconiosis law was amended in 1977, and from 1978 cases with borderline pneumoconiosis, i.e. radiographic appearance between PR0 and PR1 were classified into supervision class II. Calculation in the number of pneumoconiosis cases before 1980 included cases from occasional pneumoconiosis examination applied by individual engaged in dust-exposed work. Pneumoconiosis complications include pulmonary tuberculosis, tuberculous pleuritis, secondary pneumothorax, secondary bronchitis, secondary bronchiectasis, and primary lung cancer. Source: Results of periodic pneumoconiosis examination released by Ministry of Health, Labour and Welfare