Trends in mortality from malignant mesothelioma of the pleura, and production and use of asbestos in Australia

Our plain-English summary of Trends in mortality from malignant mesothelioma of the pleura, and production and use of asbestos in Australia, by Z. Xu, B.K. Armstrong, B.J. Blundson, et al (The Medical Journal of Australia, 1985).

The study

• Authors: Z. Xu, B.K. Armstrong, B.J. Blundson, J.M. Rogers, A.W. Musk, K.B. Shilkin
• Journal: The Medical Journal of Australia
• Published: 1985;143(5):185-7
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001252).

Abstract

Annual mortality from malignant mesothelioma of the pleura (MMP) in Australia (as represented by ICD8 codes 163.0 and 212.4, and ICD9 codes 163 and 212.4) increased in men aged 30 years and older from about 0.5/100 000 in 1968-1970 to 2.1/100 000 in 1983. Corresponding rates in women varied from 0.1/100 000 to 0.2/100 000 between 1968 and 1980, then rose to 0.3/100 000 in 1983. The rise in MMP mortality in men probably corresponds to the increasing use of asbestos, particularly amosite, in Australia during and after World War II. That production and importation of amosite and crocidolite in Australia reached a peak in 1958 may mean that peak mortality from MMP will not be reached until the 1990s (allowing a 35-year lag period). Substantial increases in importation and later production, of chrysotile in the 1950s, 1960s and 1970s may lead to increases in the incidence of other asbestos-related cancers, not reflected in trends in the incidence of MMP.

In plain English

This study examined Australian deaths from malignant mesothelioma of the pleura (MMP) from 1968 to the early 1980s and compared them with asbestos production and import records. MMP had no death-certificate code of its own, so the authors counted deaths coded as tumours of the pleura. In Western Australia, at least 38 of 47 deaths so coded (81%) were definite or possible mesothelioma. However, only 22 of 40 known mesothelioma deaths after crocidolite exposure at Wittenoom Gorge (55%) carried these codes, so the counts underestimated true deaths. There were 390 deaths in men and 87 in women. Among people aged 30 and older, men's age-standardized rates rose from about 0.5 per 100 000 in 1968 to 1971 to 1.5 in 1982. Women's rates mostly stayed between 0.1 and 0.2, then rose to 0.26 in 1981 and 1982. Crocidolite and amosite, both amphibole asbestos, became available in Australia mainly from the late 1940s, peaking around 1958. Assuming about 35 years from first exposure to death, the authors projected rising deaths into the 1990s. They cautioned that this simple projection could prove wrong.

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: Descriptive analysis of national death statistics over time (mortality trend study), compared with records of asbestos production, imports and exports, with a check of death-certificate coding against Western Australian records
• Who was studied: All deaths in Australia coded to ICD8 163.0 or 212.4, or ICD9 163 or 212.4 (malignant and benign neoplasms of the pleura), by age and sex, from Australian Bureau of Statistics data. Rates were given for persons 30 years and older. The coding check used Western Australian deaths from 1969 to 1980 and Wittenoom Gorge crocidolite-related mesothelioma deaths.
• Exposure: Annual Australian production, importation and exportation of crude asbestos, broken down where possible into crocidolite (mined at Wittenoom Gorge), amosite (imported) and chrysotile (mined in New South Wales and imported). Imports of manufactured asbestos products were not analysed.
• Main results:
  • In Western Australia, definite (33) or possible (5) mesothelioma caused at least 38 (81%) of 47 deaths coded to the chosen codes in 1969 to 1980
  • Only 22 of 40 persons (55%) who died in Western Australia from MMP after crocidolite exposure at Wittenoom Gorge had death certificates coded to the chosen codes. The most common alternative code was lung cancer (12 deaths).
  • Had all certificates mentioning mesothelioma been coded to these rubrics, sensitivity would have been 87.5%
  • Across Australia there were 390 MMP deaths in men and 87 in women. Annual numbers ranged from 10 (1970) to 58 (1982) in men and from one (1971) to 11 (1982) in women.
  • Only two of the deaths attributed to MMP were in persons under 30 years of age
  • In men aged 30 and older, age-standardized mortality rose irregularly from about 0.5/100 000 in 1968 to 1971 to 1.3/100 000 in 1978 and 1.5/100 000 in 1982. The authors described this as a fivefold increase between 1970 and 1982.
  • In women aged 30 and older, rates generally fluctuated between 0.1/100 000 and 0.2/100 000 with no consistent trend, but rose to 0.26/100 000 in 1981 and 1982
  • Deaths coded to the benign-neoplasm code 212.4 accounted for 2% to 19% (mean 8%) of total mortality in the years they occurred. Removing them left the trends substantially unaltered.
  • Crocidolite production at Wittenoom Gorge rose to a peak of 15 867 tonnes in 1962 and effectively ended when the mine closed in 1966. Of some 152 000 tonnes produced between 1950 and 1966, about 48 000 tonnes (31%) were retained in Australia.
  • Imports of amosite fluctuated around 10 000 tonnes a year between 1950/51 and 1978/79. Availability of crude amphiboles for use in Australia peaked in about 1958.
  • Chrysotile production rose steeply from 1971/72 with the opening of the Barraba mine and reached a peak of 90 524 tonnes in 1979/80
• The authors' conclusion: The authors concluded that the rise in MMP mortality in men was unlikely to be spurious. They considered that amphibole asbestos (amosite and crocidolite) appears mainly responsible for asbestos-induced MMP. Assuming a median of about 35 years from first exposure to death, they projected that MMP mortality would continue to rise into the 1990s, and possibly beyond because amosite imports continued. They also suggested that increasing chrysotile availability in the 1960s and 1970s may lead to a rise in asbestos-related lung cancer.
• Limitations the authors state:
  • The chosen death codes substantially underestimated true MMP mortality and could be affected by changes in how accurately MMP deaths were certified and coded
  • The coding check relied on Western Australian data, which the authors assumed applied to Australia as a whole
  • The authors described their projection as simple and perhaps naive, and said it may prove wrong for a number of reasons
  • The persistence of asbestos in the environment may also make the projection uncertain
  • Imports of manufactured asbestos products were recorded only as cash value and were not reported

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleura, Amosite, Crocidolite, Chrysotile.

Related studies

• Malignant mesothelioma in Australia 2015: Current incidence and asbestos exposure trends — M.J. Soeberg, J. Leigh, et al. (2016)
• Trends in mortality of diffuse malignant mesothelioma of pleura — V.E. Archer, W.N. Rom (1983)
• Incidence and survival trends for malignant pleural and peritoneal mesothelioma, Australia, 1982-2009 — M.J. Soeberg, J. Leigh, et al. (2016)
• Epidemiology of malignant mesothelioma in Western Australia — B.K. Armstrong, A.W. Musk, et al. (1984)
• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)
• Mortality from mesothelioma of the pleura during 1968-78 in England and Wales — M.J. Gardner, E.D. Acheson, et al. (1982)

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