Mortality of former crocidolite (blue asbestos) miners and millers at Wittenoom

Our plain-English summary of Mortality of former crocidolite (blue asbestos) miners and millers at Wittenoom, by A.W. Musk, N.H. de Klerk, A. Reid, et al (Occupational and Environmental Medicine, 2008).

The study

• Authors: A.W. Musk, N.H. de Klerk, A. Reid, G.L. Ambrosini, L. Fritschi, N.J. Olsen, E. Merler, M.S. Hobbs, G. Berry
• Journal: Occupational and Environmental Medicine
• Published: 2008;65(8):541-3
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Blue asbestos was mined and milled at Wittenoom in Western Australia between 1943 and 1966.

Methods: Nearly 7000 male workers who worked at the Wittenoom mine and mill have been followed up using death and cancer registries throughout Australia and Italy to the end of 2000. Person-years at risk were derived using two censoring dates in order to produce minimum and maximum estimates of asbestos effect. Standardised mortality ratios (SMRs) compare the mortality of the former Wittenoom workers with the Western Australian male population.

Results: There have been 190 cases of pleural and 32 cases of peritoneal mesothelioma in this cohort of former workers at Wittenoom. Mortality from lung cancer (SMR = 1.52), pneumoconiosis (SMR = 15.5), respiratory diseases (SMR = 1.58), tuberculosis (SMR = 3.06), digestive diseases (SMR = 1.47), alcoholism (SMR = 2.24) and symptoms, signs and ill defined conditions (SMR = 2.00) were greater in this cohort compared to the Western Australian male population.

Conclusion: Asbestos related diseases, particularly malignant mesothelioma, lung cancer and pneumoconiosis, continue to be the main causes of excess mortality in the former blue asbestos miners and millers of Wittenoom.

In plain English

This study followed up deaths among 6498 men who had mined and milled crocidolite (blue asbestos) at Wittenoom, Western Australia, at any time between 1943 and 1966. The authors described their exposure as short-term (median duration 3 months) and intense. Deaths to the end of 2000 were traced through Australian records and, for 810 men known to have gone to Italy, Italian registries. Follow-up exceeded 75%. Deaths were compared with Western Australian male death rates using standardised mortality ratios (SMRs). These were calculated two ways because some men were lost to follow-up, giving a lower estimate (SMR1) and a higher estimate (SMR2). There were 2408 deaths. The authors put the overall death rate at probably 13% to 90% higher than expected. There were 190 pleural and 32 peritoneal mesotheliomas, and the proportion of peritoneal cases had increased. Lung cancer (SMR1 1.52, SMR2 2.59), pneumoconiosis (SMR1 15.48, SMR2 27.49), tuberculosis, alcoholism, liver cirrhosis and other accidents were also raised. The paper did not examine exposure–response. The authors concluded that asbestos-related diseases continued to be the main causes of mortality in this cohort.

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: Cohort mortality follow-up study comparing observed deaths with expected deaths (standardised mortality ratios) based on Western Australian death rates
• Who was studied: 6498 male workers who mined and milled crocidolite at Wittenoom, Western Australia, between 1943 and 1966 (from a cohort of 6943 workers; fewer than 500 female workers were excluded), followed to the end of 2000, including 810 men known to have gone to Italy
• Exposure: Work in crocidolite (blue asbestos) mining and milling at Wittenoom; described by the authors as short-term (median duration 3 months) intense exposure exclusively to crocidolite
• Main results:
  • All causes: 2408 deaths observed. SMR1 was 1.13 (95% CI 1.08 to 1.17) and SMR2 was 1.90 (95% CI 1.83 to 1.98). The authors described the overall death rate as probably between 13% and 90% higher than in the general population.
  • Mesothelioma: there were 190 deaths from pleural mesothelioma and 32 from peritoneal mesothelioma in the cohort. No SMRs were given for mesothelioma.
  • The proportion of peritoneal mesothelioma cases compared with pleural mesothelioma had increased.
  • Lung cancer: 281 deaths. SMR1 was 1.52 (95% CI 1.35 to 1.71) and SMR2 was 2.59 (95% CI 2.30 to 2.91).
  • Pneumoconiosis: 91 deaths. SMR1 was 15.48 and SMR2 was 27.49 (95% CI 22.1 to 33.8). The printed confidence interval for SMR1 is garbled.
  • Tuberculosis: 12 deaths. SMR1 was 3.06 (95% CI 1.58 to 5.35) and SMR2 was 4.38 (95% CI 2.26 to 7.35).
  • Alcoholism: 28 deaths, SMR1 2.24 (95% CI 1.49 to 3.23). Liver cirrhosis: 61 deaths, SMR1 1.71 (95% CI 1.31 to 2.20).
  • Other (non-transport) accidents: 95 deaths. SMR1 was 1.85 (95% CI 1.50 to 2.26) and SMR2 was 2.64 (95% CI 2.13 to 3.22).
  • The authors reported a borderline increase in upper aerodigestive and oesophageal cancer mortality and a slightly increased risk of stomach cancer mortality. Upper aerodigestive: SMR1 1.34 (95% CI 0.90 to 1.92). Oesophagus: SMR1 0.68 (95% CI 0.35 to 1.18). Stomach: SMR1 1.01 (95% CI 0.71 to 1.40). The authors said these cancers did not appear to be related to indices of crocidolite exposure.
• The authors' conclusion: The authors concluded that asbestos-related diseases (malignant mesothelioma, lung cancer and pneumoconiosis) continue to be the main causes of mortality among this cohort of male former Wittenoom crocidolite miners and millers followed to the end of 2000.
• Limitations the authors state:
  • Because some workers were lost to follow-up, SMRs were given as lower and upper estimates. The authors state the true SMR lies somewhere between the two.
  • Follow-up of the workforce was incomplete, reported as exceeding 75%.
  • The paper does not examine exposure–response relationships.
  • Female workers (fewer than 500) were not included; follow-up was restricted to male workers.

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: Crocidolite, Wittenoom, Peritoneal Mesothelioma, Lung Cancer, Pneumoconiosis, Mesothelioma.

Related studies

• Malignant pleural and peritoneal mesotheliomas in former miners and millers of crocidolite at Wittenoom, Western Australia — G. Berry, N.H. de Klerk, et al. (2004)
• 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)
• Benign and malignant pleural effusions in former Wittenoom crocidolite millers and miners — W.O. Cookson, N.H. De Klerk, et al. (1985)
• 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)
• Migration and work in postwar Australia: mortality profile comparisons between Australian and Italian workers exposed to blue asbestos at Wittenoom — A. Reid, E. Merler, et al. (2018)
• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)

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