Compensation, radiographic changes, and survival in applicants for asbestosis compensation

Our plain-English summary of Compensation, radiographic changes, and survival in applicants for asbestosis compensation, by W.O. Cookson, A.W. Musk, J.J. Glancy, et al (British Journal of Industrial Medicine, 1985).

The study

• Authors: W.O. Cookson, A.W. Musk, J.J. Glancy, N.H. de Klerk, R. Yin, R. Mele, N.G. Carr, B.K. Armstrong, M.S. Hobbs
• Journal: British Journal of Industrial Medicine
• Published: 1985;42(7):461-8
• 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. 000468).

Abstract

The survival of 354 claimants for compensation for pulmonary asbestosis among former workers of the Wittenoom crocidolite mine and mill in Western Australia has been examined. There were 118 deaths up to December 1982. The median time between start of work and claim for compensation was 17 years. The standardised mortality ratio (SMR) for deaths from all causes was 2.65 (p less than 0.0001). The SMR for pneumoconiosis was 177.2 (p less than 0.0001), bronchitis and emphysema 2.6 (p = 0.04), tuberculosis 44.6 (p less than 0.0001), respiratory cancer (including five deaths from malignant pleural mesothelioma) 6.4 (p less than 0.0001), gastrointestinal cancer 1.6 (p = 0.22), all other cancers 1.6 (p = 0.17), heart disease 1.4 (p = 0.07), and all other causes 2.18 (p = 0.004). Plain chest radiographs taken within two years of claiming compensation were found for 238 subjects and were categorised independently by two observers according to the International Labour Organisation criteria without knowledge of exposure or compensation details. Profusion of radiographic opacities, age at claiming compensation, work in the Wittenoom mill, and degree of disability awarded by the pneumoconiosis medical board were significant predictors of survival, but total estimated exposure to asbestos was not. Radiographic profusion and degree of disability were, however, predictable by total exposure. The median survival from claim for compensation was 17 years in subjects with ILO category 1 pneumoconiosis, 12 years in category 2, and three years in category 3.

In plain English

This study followed 354 men who applied for compensation for pneumoconiosis between 1947 and December 1982. They were among about 7000 former workers at the Wittenoom crocidolite mine and mill in Western Australia, where there was also exposure to silica. By December 1982, 118 had died. Overall deaths were 2.65 times the number expected from Western Australian death rates. Deaths from pneumoconiosis, respiratory cancer (including five malignant pleural mesotheliomas), tuberculosis, and bronchitis and emphysema were raised. Gastrointestinal and other cancers were not significantly raised. Two observers read chest radiographs taken within two years of the claim for 238 men, using ILO criteria. Median survival from the claim was 17 years in ILO category 1, 12 years in category 2 and three years in category 3. Radiographic profusion, age at starting work, time since starting work and mill work predicted death. Estimated total exposure did not, although it did predict profusion and the disability percentage awarded. Among 168 men awarded compensation, higher disability percentage predicted death. The authors noted that smoking data were insufficient to include.

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: Mortality and survival follow-up of compensation claimants, with observed deaths compared with expected deaths from age, period and sex specific Western Australian death rates; survival analysis and regression of predictors
• Who was studied: 354 men, out of about 7000 workers at Wittenoom, Western Australia, who applied for compensation for pneumoconiosis between 1947 and December 1982; radiograph analyses in 238 men; disability analyses in 168 men awarded compensation
• Exposure: Crocidolite mined and milled at Wittenoom Gorge and Colonial Gorge between 1943 and 1966, with exposure also to silica, especially in the mine. Total exposure in fibre/cc years was estimated from work histories and 1966 fibre counts.
• Main results:
  • 118 deaths among the 354 claimants up to December 1982; standardised mortality ratio for all causes 2.65 (p less than 0.0001)
  • Standardised mortality ratio for pneumoconiosis 177.2 (p less than 0.0001) in the 354 claimants
  • Standardised mortality ratio for bronchitis and emphysema 2.6 (p = 0.04) and for tuberculosis 44.6 (p less than 0.0001)
  • Respiratory cancer deaths included five cases of malignant pleural mesothelioma
  • Gastrointestinal cancer (SMR 1.6, p = 0.22), all other cancers (1.6, p = 0.17) and heart disease (1.4, p = 0.07) were not statistically significant
  • 238 subjects had chest radiographs within two years of claim, categorised independently by two observers using ILO criteria
  • Median survival from claim: 17 years in ILO category 1, 12 years in category 2, three years in category 3
  • In the 238 subjects, radiographic profusion predicted death from all causes (relative risk 1.26 per minor ILO category, reader 1; 1.23, reader 2), along with age at starting work, time since starting work and mill working
  • Estimated total cumulative exposure was not a predictor of mortality
  • Total exposure replaced mill working as a predictor only when estimated mill exposure was increased by a factor of 50
  • Radiographic profusion was predicted by (log) total exposure, age at starting work and time since starting work
  • In 168 subjects awarded compensation, the percentage disability awarded was a positive predictor of death from all causes
  • Median survival was 24 years for 26-50% disability, 14 years for 51-75% and 12 years for 76-100%
  • Percentage disability awarded was itself predicted by total exposure to asbestos (p less than 0.0001) and age at starting work
  • Percentage disability was the single best predictor of death from lung cancer
• The authors' conclusion: The authors concluded that compensation claimants among Wittenoom crocidolite workers had excess mortality, that survival was significantly related to radiographic category of asbestosis and percentage disability compensated, and that excess mortality associated with mill work could not be satisfactorily accounted for by estimates of total exposure
• Limitations the authors state:
  • Smoking information was not included in the analysis because of insufficient data
  • The 1966 exposure concentrations may have been conservative estimates of usual concentrations in the mills
  • The lack of an exposure effect on lung cancer mortality may reflect subject selection, the limited exposure range, small numbers of cases or missing tobacco data
  • The analysis assumed independence of competing causes of death, which the authors considered probably invalid

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: Asbestosis, Crocidolite.

Medical terms in this study, explained in our Lexicon: Asbestosis, Wittenoom, Crocidolite, Pneumoconiosis, Emphysema, Pleural Mesothelioma, Chest X-Ray, Median Survival.

Related studies

• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)
• Radiographic abnormalities and mortality in subjects with exposure to crocidolite — N.H. de Klerk, A.W. Musk, et al. (1993)
• The cost of compensating asbestos victims under the Occupational Disease Compensation Act of 1983 — F.B. Siskind (1987)
• Sputum asbestos bodies and radiographic changes in residents of Wittenoom, Western Australia — A.W. Musk, J.E. Baker, et al. (1983)
• TruCutR needle biopsy in asbestosis and silicosis: correlation of histological changes with radiographic changes and pulmonary function in 41 patients — P. Tukiainen, E. Taskinen, et al. (1978)
• The natural history of asbestosis in former crocidolite workers of Wittenoom Gorge — W. Cookson, N. De Klerk, et al. (1986)

Browse more research in British Journal of Industrial Medicine, or return to medical research.