Thirty-two cases of mesothelioma in Victoria, Australia: a retrospective survey related to occupational asbestos exposure

Our plain-English summary of Thirty-two cases of mesothelioma in Victoria, Australia: a retrospective survey related to occupational asbestos exposure, by J.E. Milne (British Journal of Industrial Medicine, 1976).

The study

• Author: J.E. Milne
• Journal: British Journal of Industrial Medicine
• Published: 1976;33(2):115-22
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002301).

Abstract

Mesotheliomas have been reported in four states in Australia. Crocidolite has been mined and milled at Wittenoom in West Australia where five cases of mesothelioma were reported after exposure of high intensity. The 32 cases of mesothelioma reported in this paper occurred during a period of 11 years in Victoria; 29 were pleural and three peritoneal. There were 22 autopsies. End occupations were misleading in 66% of cases. Two of the three subjects with peritoneal mesothelioma were siblings, and there was no evidence of occupational or other exposure to asbestos in either. There was a significant prevalence of pulmonary asbestos bodies in the tumour series as compared with an unselected consecutive series of 200 routine autopsies (0.01 greater than P greater than 0.001). The occupational history was as effective a method of assessing 'true' asbestos exposure as the pulmonary asbestos body count. Five cases had had a duration of exposure of one year or less, but they had had heavy exposure. The latent interval before tumour development was 25 years or longer in each case. There was no known exposure to asbestos in five cases (16%). The rare association of mesothelioma with types of asbestos other than crocikolite may not exist and could be explicable on the basis of the proportion (16%) of these tumours arising randomly in the population.

In plain English

This was a retrospective survey of 32 people with mesothelioma diagnosed in Victoria, Australia, from 1962 to the end of 1973. Twenty-nine had pleural and three had peritoneal mesothelioma. Twenty-two diagnoses were confirmed at autopsy and 10 by pleural biopsy. The author graded each person's past asbestos exposure from work histories and searched lung tissue for asbestos bodies. Fourteen people had 'certain' exposure. Of 27 with some possible work exposure, eight had worked in dockyards and five had wound crocidolite string onto welding rods. Asbestos bodies were found in 15 of 21 autopsied cases. An earlier routine autopsy series by other researchers found them in 87 of 200, and the difference was significant at the 1% level. The job held at diagnosis could have been misleading in at least 21 cases (66%). Five people (16%) had no evidence of asbestos exposure. Two of the peritoneal cases were a brother and sister, neither with asbestos bodies found. The author concluded that occupational asbestos exposure was related to mesothelioma after about 20 years, and that some mesotheliomas occur unrelated to asbestos.

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: Retrospective survey (case series) of mesothelioma cases, with occupational histories assessed by the author and lung tissue examined for asbestos bodies
• Who was studied: 32 mesothelioma cases (29 pleural, 3 peritoneal) diagnosed in Victoria, Australia, from 1962 to the end of 1973. Twenty-three came from the Thoracic Unit of the Austin Hospital, Melbourne, and nine from seven other institutions. Twenty-two had autopsy and 10 were diagnosed by pleural biopsy.
• Exposure: Past occupational asbestos exposure, graded from work histories as 'nil', 'possible', 'probable' or 'certain'; 14 subjects had 'certain' exposure. Jobs included dockyard work, binding crocidolite string onto welding rods (Cases 1 to 5, using South African crocidolite), welding, lagging, asbestos spraying and asbestos carding. Most patients had mixed exposure to more than one type of asbestos.
• Main results:
  • Asbestos bodies were found in 15 of 21 autopsied mesothelioma cases. An earlier unselected consecutive series of 200 routine autopsies in Victoria (Xipell and Bhathal, 1969) found them in 87 cases. The author reported the difference as significant at the 1% level (chi-squared 7.14, P less than 0.01).
  • The occupational history and the finding of asbestos bodies showed no significant difference as indicators of 'true' asbestos exposure (chi-squared 0.62).
  • The occupation held at the time of tumour diagnosis ('end occupation') could have been misleading in at least 21 of the 32 cases (66%).
  • Five of the 32 cases (16%) had no evidence linking them to asbestos.
  • In the five welding-electrode workers exposed solely to imported crocidolite (Cases 1 to 5), at least 20 years passed between the start of exposure and development of mesothelioma.
  • Five cases, all male, were exposed for a year at most. Their exposure began about 25 years or earlier before the tumour developed. In Case 12, six months of heavy exposure in 1942 indicated a latent interval of 25 years.
  • No case in the series began exposure after 1943.
  • Two of the three peritoneal mesothelioma cases (Cases 21 and 22) were brother and sister, and no asbestos bodies were found in either. The brother's exposure was rated at most 'possible', and even this appeared doubtful. No evidence of asbestos exposure was found for the sister.
• The authors' conclusion: The author concluded that this small series confirmed a relationship in Victoria between occupational asbestos exposure and later mesothelioma, after an elapsed time of the order of 20 years. The author also concluded that end occupations bear little relationship to past exposure, and that the occupational history is as effective as an asbestos body count. The 16% with no evidence of exposure indicated, in the author's view, that some mesotheliomas occur unrelated to asbestos, possibly in larger numbers than suspected. The author suggested that the so-called rare association of mesothelioma with asbestos types other than crocidolite may not exist.
• Limitations the authors state:
  • The series could not be analysed by type of asbestos because most patients had mixed exposure.
  • Because asbestos was widely used, some subjects could have been wrongly classed as having possible or probable exposure; the author named Case 19 as one possible example.
  • For long exposures that continued until diagnosis, the elapsed time gives no indication of the true latent interval between dose and response.

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, Asbestos Exposure, Crocidolite, Wittenoom, Peritoneal Mesothelioma, Asbestos Bodies, Occupational History.

Related studies

• Fifteen cases of pleural mesothelioma associated with occupational exposure to asbestos in Victoria — J. Milne (1969)
• Occupational and environmental risk factors for idiopathic pulmonary fibrosis in Australia: case-control study — M.J. Abramson, T. Murambadoro, et al. (2020)
• Development of a Job-Exposure Matrix (AsbJEM) to Estimate Occupational Exposure to Asbestos in Australia — S.C. van Oyen, S. Peters, et al. (2015)
• Distribution of mesothelioma cases in different occupational groups and industries in Australia, 1979-1995 — P. Yeung, A. Rogers, et al. (1999)
• The future excess fraction of occupational cancer among those exposed to carcinogens at work in Australia in 2012 — R.N. Carey, S.J. Hutchings, et al. (2017)
• Occupational health in Australia — W.O. Phoon (1998)

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