Development of a Job-Exposure Matrix (AsbJEM) to Estimate Occupational Exposure to Asbestos in Australia

Our plain-English summary of Development of a Job-Exposure Matrix (AsbJEM) to Estimate Occupational Exposure to Asbestos in Australia, by S.C. van Oyen, S. Peters, H. Alfonso, et al (The Annals of Occupational Hygiene, 2015).

The study

• Authors: S.C. van Oyen, S. Peters, H. Alfonso, L. Fritschi, N.H. de Klerk, A. Reid, P. Franklin, L. Gordon, G. Benke, A.W. Musk
• Journal: The Annals of Occupational Hygiene
• Published: 2015;59(6):737-48
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Occupational exposure data on asbestos are limited and poorly integrated in Australia so that estimates of disease risk and attribution of disease causation are usually calculated from data that are not specific for local conditions.

Objective: To develop a job-exposure matrix (AsbJEM) to estimate occupational asbestos exposure levels in Australia, making optimal use of the available exposure data.

Methods: A dossier of all available exposure data in Australia and information on industry practices and controls was provided to an expert panel consisting of three local industrial hygienists with thorough knowledge of local and international work practices. The expert panel estimated asbestos exposures for combinations of occupation, industry, and time period. Intensity and frequency grades were estimated to enable the calculation of annual exposure levels for each occupation-industry combination for each time period. Two indicators of asbestos exposure intensity (mode and peak) were used to account for different patterns of exposure between occupations. Additionally, the probable type of asbestos fibre was determined for each situation.

Results: Asbestos exposures were estimated for 537 combinations of 224 occupations and 60 industries for four time periods (1943-1966; 1967-1986; 1987-2003; ≥2004). Workers in the asbestos manufacturing, shipyard, and insulation industries were estimated to have had the highest average exposures. Up until 1986, 46 occupation-industry combinations were estimated to have had exposures exceeding the current Australian exposure standard of 0.1 f ml(-1). Over 90% of exposed occupations were considered to have had exposure to a mixture of asbestos varieties including crocidolite.

Conclusion: The AsbJEM provides empirically based quantified estimates of asbestos exposure levels for Australian jobs since 1943. This exposure assessment application will contribute to improved understanding and prediction of asbestos-related diseases and attribution of disease causation.

© The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

In plain English

This study built AsbJEM, a job-exposure matrix estimating occupational asbestos exposure in Australia since 1943, excluding the Wittenoom mine. Three occupational hygienists reviewed Australian and international exposure information, including 3497 airborne asbestos measurement records. For each job, industry and period, they agreed on usual ('mode') and short, intense ('peak') exposure intensity and frequency, and likely fibre type. These grades gave annual average exposure estimates. Of 537 combinations of 224 occupations and 60 industries, 486 were judged above background at some time. Over 90% of exposed occupations were judged to involve a fibre mixture including crocidolite. Up until 1986, 46 combinations were estimated to exceed the current Australian standard of 0.1 fibres per millilitre. Before 1987, estimates reached up to 12 fibres per millilitre in asbestos manufacturing and 2.44 for asbestos removalists and insulators. For 1987 to 2003, exposures above 0.1 as an eight-hour time-weighted average were no longer considered to have occurred. Without adequate measurements, earliest-period estimates rested on expert opinion and literature on consumption and industry practice. The authors concluded the matrix will aid understanding and prediction of asbestos-related diseases.

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: Exposure assessment study: development of a job-exposure matrix by an expert panel, using available measurement data and literature
• Who was studied: 537 combinations of 224 occupations and 60 industries in Australia with potential asbestos exposure, assessed for four time periods (1943–1966, 1967–1986, 1987–2003, 2004 onwards)
• Exposure: Occupational airborne asbestos, estimated by a panel of three occupational hygienists from 3497 measurement records and other information. Fibre type was classed as amosite, chrysotile, mixture including crocidolite, or mixture not including crocidolite. Intensity was graded from background (0.0001 f/ml) to very high (37.5 f/ml) as an 8-hour time-weighted average, for both mode and peak exposure.
• Main results:
  • Of the 537 occupation-industry combinations, 486 were assessed as having asbestos exposure above background level in at least one time period.
  • In occupations with exposure above background, the fibre type was most often (more than 90%) judged to be a mixture of fibres including crocidolite.
  • The panel assigned the same values to every job-industry combination for 1943–1966 and 1967–1986, so these periods were reported together as 1943–1986.
  • Up until 1986, 46 occupation-industry combinations were estimated to have exposures exceeding the current Australian exposure standard of 0.1 f/ml.
  • Before 1987, estimated annual average exposures were up to 12 f/ml for occupations in the asbestos manufacturing industry, and 2.44 f/ml for asbestos removalists and insulators.
  • For fitters in 1943–1986, estimated annual average exposure ranged from 0.0002 f/ml in transport to 0.5719 f/ml in asbestos manufacturing.
  • For 1987–2003, exposures above 0.1 f/ml as an 8-hour time-weighted average were no longer considered to have occurred.
  • From 2004 onwards, mode exposures were set at background levels, but peak exposures still gave slightly raised annual averages for some occupations, such as asbestos removalists and boilermakers/welders.
• The authors' conclusion: The authors concluded that AsbJEM provides quantified estimates of asbestos exposure for Australian jobs since 1943, and that it will contribute to better understanding and prediction of asbestos-related diseases and to attribution of disease causation.
• Limitations the authors state:
  • For the first time period, there were no adequate exposure measurements, so estimates were based solely on expert opinion and the literature on asbestos consumption and industry practice.
  • The experts appeared to be most confident of their estimates for 1967 to 2003.
  • A JEM gives the most likely exposure for each job, industry and period, and does not capture variation between individuals in the same job.
  • Monitoring before 1984 regulations in Western Australia was ad hoc and site-specific.
  • Most of the measurement data were not collected for research purposes.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Attribution, Causation, Asbestos Exposure, Crocidolite.

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