Work environment of plants manufacturing asbestos-containing products in Japan

Our plain-English summary of Work environment of plants manufacturing asbestos-containing products in Japan, by T. Higashi, H. Hori, H. Sakurai, et al (The Annals of Occupational Hygiene, 1994).

The study

• Authors: T. Higashi, H. Hori, H. Sakurai, K. Omae, T. Tsuda, I. Tanaka, T. Satoh, H. Hoshi
• Journal: The Annals of Occupational Hygiene
• Published: 1994;38(4):489-94, 409
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In 1985, a comprehensive study of asbestos-containing product plants (A/C, friction, textile) was performed. The data presented were based not on personal but on area sampling. A conversion equation from area sampling data to personal exposure values was developed. Exposure concentrations were 0.07-0.66 f ml-1. In workplaces which belonged to member companies of the Japan Asbestos Association, the percentage of workplaces whose exposure concentrations was less than 0.3 f ml-1 was 70% in 1985 (N = 510), but 98% in 1992 (N = 430). Concentrations in a new, well-controlled A/C plant were less than 0.1 f ml-1.

In plain English

This study measured airborne asbestos fibres in Japanese plants making asbestos-containing products. Japanese rules rely on fixed-point (area) air sampling, not samplers worn by workers. So the main aim was an equation converting area results into personal exposure. In 1985 the authors sampled five plants: a roofing-material plant, an asbestos-cement sheet plant, a friction-material plant, and two construction and roofing-material plants. Workers in four process groups also wore personal samplers. Mixing showed high area concentrations with very wide variation. Personal exposure was high in cutting, grinding and drilling, especially manual cutting of non-standardized items, though grinding was relatively low. The authors calculated a conversion factor of around 0.3 from the area-based maximum estimate (E1) to personal exposure. Among Japan Asbestos Association member workplaces, the share with estimated exposure below 0.3 fibres per millilitre was 70% in 1985 (510 workplaces) and 98% in 1992 (430 workplaces). A remodelled asbestos-cement plant was below 0.1 fibres per millilitre. Relatively high exposure remained in small textile mills and parts of construction. The authors attributed the improvement mainly to enclosed processes, local ventilation and process changes.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Workplace air-monitoring study: parallel area (stationary) and personal air sampling in 1985, plus trend monitoring of member-company workplaces from 1984 to 1992
• Who was studied: In 1985: five Japanese plants, with two manufacturing and processing workplaces sampled in each. The plants were a roofing-material plant, an asbestos-cement sheet plant, a friction-material plant and two construction and roofing-material plants. Personal samples came from 4, 3, 9 and 4 workers in the four process groups. Trend monitoring covered workplaces of Japan Asbestos Association member companies: 510 workplaces in 1984 and 430 in 1992.
• Exposure: Airborne asbestos fibres counted by optical microscopy at a magnification of x400. The article calls the method 'phase-contact optical microscopy'. Processes: disintegrating (feeding), mixing, cutting/grinding/drilling, and others. The article does not state the fibre type at the sampled plants. It reports that Japanese asbestos demand was 95% chrysotile in 1988 and 99% in 1993, and the standards it cites are for chrysotile.
• Main results:
  • A high area concentration, with a very high geometric standard deviation, was measured in the mixing process.
  • High personal exposure levels were seen in cutting, grinding and drilling, especially in manual cutting of non-standardized items. In the grinding process itself, exposure concentrations were relatively low.
  • The conversion coefficient from the area-based E1 value to personal exposure was calculated to be around 0.3.
  • Using the conversion equation, exposure was estimated at less than 0.6 fibres per millilitre in workplaces meeting the administrative standard, and less than 0.3 in workplaces meeting the self-administered standards.
  • Among Japan Asbestos Association member workplaces, the percentage with exposure concentrations below 0.3 fibres per millilitre was 70% in 1985 (n = 510) and 98% in 1992 (n = 430).
  • Concentrations in a re-modelled, well-controlled asbestos-cement plant were less than 0.1 fibres per millilitre.
  • Relatively high exposure still remained in small textile mills and in some parts of the construction industry.
• The authors' conclusion: The authors concluded that the percentage of workplaces meeting the standards had been increasing sharply. They attributed this mainly to enclosure of the manufacturing process, local ventilation and/or changes in the process, and to a lesser extent to the closure of small plants with more primitive conditions.
• Limitations the authors state:
  • Personal exposure and E1 values corresponded to each other, but the variance was larger at high exposures.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

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