Pneumoconiosis in construction workers refocused
by TOYAMA Naoki
East Tokyo Occupational Safety and Health Center (ETOSHC)
Japanese construction workers have found themselves exposed to massive doses of dust in their construction sites since the 1960's. Since then the construction industry began to introduce motor-driven tools and many kinds of new construction materials, which were made to be immediately fixed into the structures of buildings.
What has made the situation more complicated is the use of asbestos materials. While many countries ban the import of this hazardous material, Japan imports approximately 180,000 tons of asbestos every year, most of which is used in the manufacture of slates, boards, water pipes and tiles.
Asbestos is among those materials which are statutorily classified as carcinogenic, and required to be strictly controlled during handling and processing. It is difficult to effectively prevent environmental pollution and exposure to human beings, partly because the job categories involved on building sites range widely from carpentry and plastering to wiring and piping, and partly because people are working under a complicated contractual hierarchy. As a result, construction workers have been left without virtually any protective measures to resort to, despite their polluted working environment.
Now the time has come when the workers who began to handle motor-driven tools and new construction materials in 1960's find that the possible consequences of their dust-exposed work take the form of pneumoconiosis or asbestosis. The East Tokyo Occupational Safety and Health Center (ETOSHC) has been working on dust problems in the construction industry with a construction workers union in Tokyo.
Here follows a description of our activities.
1) Re-reading of chest X-ray films
About 5,000 workers in the metropolitan region, who are organized by the union, annually receive a statutory medical check-up, including a chest X-ray. The chest X-ray film is taken mainly to help detect potential tuberculosis or lung cancer, with the result that there is no focus on pneumoconiosis. To identify pneumoconiosis victims at as early a stage as possible, in late 1997 we asked experts collaborating in monitoring and treating the disease to re-read all the chest X-ray films of these workers.
2) Pneumoconiosis examinations
Following the screening, on December 14, 1997 we organized pneumoconiosis-centered examinations, including a respiratory function test and sputum examination for workers suspected of suffering from the disease.
One hundred and ten workers participated in the program (the mean age was 54.7 years, and the mean duration of work was 33.8 years). Additional X-ray photography revealed that 31 workers had granular opacity in their lungs, and that 70 workers had irregular opacity. The number of workers showing any evidence of pneumoconiosis totaled 86. In six of them the disease was diagnosed to be severer than grade 1/0 under the official classification scheme, which meant that they should be officially registered and monitored under the Pneumoconiosis Law. Overall, two workers were normal, while 86 were suffering from pneumoconiosis in the early stage, including 15 workers in a very early stage.
To help understand the relationship of specific types of dust with the disease, the organizing staff documented a detailed occupational history of individual workers.
3) Investigation into causes of death
We started to investigate the cause of death of 1,286 deceased workers, using accumulated data on age, job category and cause of death. We are planning to organize a hands-on training program for preventing dust exposure, and hope to identify the sources of exposure using dust monitoring techniques.
JOSHRC NEWSLETTER No.14 (Mar, 1998)
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