Malignant pleural and peritoneal mesotheliomas in former miners and millers of crocidolite at Wittenoom, Western Australia

Our plain-English summary of Malignant pleural and peritoneal mesotheliomas in former miners and millers of crocidolite at Wittenoom, Western Australia, by G. Berry, N.H. de Klerk, A. Reid, et al (Occupational and Environmental Medicine, 2004).

The study

• Authors: G. Berry, N.H. de Klerk, A. Reid, G.L. Ambrosini, L. Fritschi, N.J. Olsen, E. Merler, A.W. Musk
• Journal: Occupational and Environmental Medicine
• Published: 2004;61(4):e14
• Cited by: 58 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Aims: To report the number of malignant pleural and peritoneal mesotheliomas that have occurred in former Wittenoom crocidolite workers to the end of 2000, and to compare this with earlier predictions.

Methods: A group of 6493 men and 415 women who had worked at the former Wittenoom crocidolite mine and mill at some time between 1943 and 1966 have been followed up throughout Australia and Italy to the end of 2000.

Results: The cumulative number of mesotheliomas up to 2000 was 235 in men (202 pleural, 33 peritoneal) and seven (all pleural) in women. There had been 231 deaths with mesothelioma (9% of known deaths).

Conclusions: The number of deaths in men with mesothelioma between 1987 and 2000 was at the low end of the predictions made earlier based on the number of cases to 1986. If this trend continues, it is predicted that about another 110 deaths with mesothelioma will occur in men by 2020.

In plain English

This follow-up study tracked 6493 men and 415 women who worked at the Wittenoom crocidolite (blue asbestos) mine and mill in Western Australia between 1943 and 1966, to the end of 2000. Most worked there briefly: 45% of men stayed less than three months. By the end of 2000 there had been 235 mesotheliomas in men (202 pleural, 33 peritoneal) and seven in women (all pleural). There were 224 mesothelioma deaths in men and seven in women, which was 9% of known deaths in men and 7% in women. Among 230 people diagnosed before death who later died, median survival was 8.3 months. Survival was shorter for those diagnosed at 60 or older and did not change significantly over time. The 224 deaths in men were slightly below the lowest of the three earlier predictions compared (234). The authors said this gave some evidence for models in which crocidolite is gradually cleared from the lungs. They predicted about another 110 deaths in men by 2020 if the trend continues. Some workers who emigrated were lost to follow-up, so the true rates may be a little higher.

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: Follow-up study of a group of former workers. It reports mesothelioma cases and deaths, compares the observed numbers with earlier model predictions, and analyses survival after diagnosis.
• Who was studied: 6493 men and 415 women who had worked at the former Wittenoom crocidolite mine and mill, Western Australia, at some time between 1943 and 1966. They were followed up throughout Australia and in Italy to the end of 2000.
• Exposure: Crocidolite (blue asbestos) mining and milling. Employment was usually short: 45% of men worked less than three months, and less than 3% stayed five years or longer. Almost 90% of the men worked in the mine, the mill, or both. Few women did, so their exposures were lower.
• Main results:
  • Up to the end of 2000 there were 235 mesothelioma cases in men (202 pleural and 33 peritoneal) and seven in women (all pleural).
  • Up to the end of 2000 there were 224 deaths with mesothelioma in men (192 pleural and 32 peritoneal) and seven in women (all pleural).
  • Nine per cent of known deaths in men and 7% of known deaths in women were with mesothelioma. Mesothelioma deaths had reached 3.4% of all male workers and 1.7% of female workers.
  • In 239 deaths (including eight in 2001 or 2002), the time from first starting at Wittenoom to death with mesothelioma ranged from 13 years and 5 months to 53 years. The average was 32.9 years.
  • By the end of 2000, 224 mesothelioma deaths were observed in men. The earlier models had predicted 320 (model 1), 267 (model 2) and 234 (model 3).
  • The authors interpreted the 1987 to 2000 numbers, which were similar to the lowest predictions, as some evidence that models allowing for gradual elimination of crocidolite from the lungs are more realistic.
  • There were 242 men and women with mesothelioma. Of the 239 known to have died (including deaths in 2001 or 2002), nine were diagnosed only at death. For the other 230, median survival from diagnosis was 8.3 months (interquartile range 4.5 to 16.9 months). Three people were not known to have died.
  • Median survival was 8.8 months for those diagnosed under age 60 (n = 124) and 7.7 months for those aged 60 or older (n = 106). The longer survival at younger ages was statistically significant (p = 0.003). The difference between the three diagnosis periods was not (p = 0.67).
• The authors' conclusion: The authors concluded that if mesotheliomas continue at the lowest end of the earlier predictions, there would be about a further 110 deaths in men from mesothelioma by the end of 2020. They described this as a high continuing toll, though not as high as some earlier predictions.
• Limitations the authors state:
  • Some former workers emigrated from Australia and were lost to follow-up, so the true rates may be a little higher.
  • Follow-up relied on matching deaths and cancer notifications. People with no match are not necessarily still alive and free of cancer.
  • Some information exists for 2001 and 2002, but follow-up for those years is incomplete.
  • The predictions assumed no other factors affected mesothelioma incidence. About a third of former workers had taken part in a vitamin A prevention programme since 1990, which the authors estimated could have reduced cases by about one twelfth (about 10 cases) between 1990 and 2000.
  • The relevance of lung clearance to peritoneal mesotheliomas is unknown. Since 86% of the mesotheliomas were pleural, the authors said this would not have influenced their results greatly.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Wittenoom, Western Australia

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Crocidolite, Wittenoom, Mesothelioma.

Related studies

• Malignant mesotheliomas in former miners and millers of crocidolite at Wittenoom (Western Australia) after more than 50 years follow-up — G. Berry, A. Reid, et al. (2012)
• Mortality of former crocidolite (blue asbestos) miners and millers at Wittenoom — A.W. Musk, N.H. de Klerk, et al. (2008)
• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)
• Retinol supplementation and mesothelioma incidence in workers earlier exposed to blue asbestos (Crocidolite) at Wittenoom, Western Australia — H.S. Alfonso, A. Reid, et al. (2010)
• Plasma vitamin concentrations and incidence of mesothelioma and lung cancer in individuals exposed to crocidolite at Wittenoom, Western Australia — H.S. Alfonso, L. Fritschi, et al. (2006)
• Plasma retinol, carotene and vitamin E concentrations and lung function in a crocidolite-exposed cohort from Wittenoom, Western Australia: a cohort study — H.S. Alfonso, L. Fritschi, et al. (2005)

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