Relationship between occupations and asbestos-fibre content of the lungs in patients with pleural mesothelioma, lung cancer, and other diseases

Our plain-English summary of Relationship between occupations and asbestos-fibre content of the lungs in patients with pleural mesothelioma, lung cancer, and other diseases, by F. Whitwell, J. Scott, M. Grimshaw (Thorax, 1977).

The study

• Authors: F. Whitwell, J. Scott, M. Grimshaw
• Journal: Thorax
• Published: 1977;32(4):377-86
• Cited by: 141 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. 002257).

Abstract

Whitwell, F., Scott, Jean, and Grimshaw, Myra (1977).Thorax, 32, 377-386. Relationship between occupations and asbestos-fibre content of the lungs in patients with pleural mesothelioma, lung cancer, and other diseases. The light-visible asbestos-fibre content of 300 lung specimens has been measured using a potash-digestion and phase-contrast microscopy technique, and the results have been correlated with the occupations of the patients. Among 100 pleural mesothelioma specimens were 88 where the patients had been exposed to asbestos, and in 73 of these (83%) the lung tissue contained over 100 000 asbestos fibres per gram of dried lung, and only one specimen showed less than 20 000 fibres per gram. When asbestosis was present, the lungs nearly always showed over 3 million fibres per gram. In 100 control lungs (those without industrial disease or lung cancer) there were less than 20 000 fibres per gram of dried lung in 71% of specimens. Lungs from 100 patients with lung cancer but no industrial disease contained less than 20 000 fibres per gram of dried lung in 80% of cases. Patients with parietal pleural plaques nearly all had over 20 000 fibres per gram in their lungs. The number of asbestos fibres found in the lungs was closely related to the occupations of the patients but not to their home environment. Patients who had lived near likely sources of atmospheric asbestos pollution did not have higher asbestos fibre counts than the rest of the patients. It is concluded that there is a definite dose relationship between asbestos exposure and mesothelioma formation but that' `sub-asbestosis' levels of asbestos exposure do not contribute to the formation of lung cancer in those not subjected to industrial asbestos exposure.

In plain English

This Liverpool study counted light-visible asbestos fibres in 300 lung specimens and compared counts with work histories. These were 100 pleural mesothelioma necropsy lungs (north-west England, 1973 to 1976), 100 controls without industrial lung disease or lung cancer, and 100 surgical lung cancer specimens. Counted fibres were nearly always amphibole; finer chrysotile was hard to see. Of 88 mesothelioma patients with asbestos exposure histories, 73 (83%) had over 100 000 fibres per gram of dried lung, and all but one over 20 000. Among controls 71%, and among lung cancer patients 80%, had under 20 000 fibres per gram of dried lung. Higher counts went with patients' jobs. In 73 control and lung cancer patients who mostly lived in one Merseyside district, high counts were not concentrated near docks or shipyards. The authors concluded there was a definite dose relationship between asbestos exposure and mesothelioma, and that 'sub-asbestosis' exposure did not contribute to lung cancer in people without industrial exposure. They noted the study could not show whether asbestos workers can develop lung cancer from asbestos without first having asbestosis.

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: Pathology study measuring lung asbestos-fibre content (potash digestion and phase-contrast light microscopy) in three series of lung specimens, correlated with occupational and residential histories
• Who was studied: 300 lung specimens. 100 consecutive pleural mesothelioma lungs obtained at necropsy, submitted by coroners in north-west England to the Manchester Pneumoconiosis Medical Panel, 1973 to 1976 (86 male, 14 female). 100 control lungs from Broadgreen Hospital necropsies in 1975 and 1976 in people over 20 without industrial lung disease or lung cancer (72 male, 28 female). 100 lung cancer lungs or lobes removed surgically at Broadgreen Hospital in 1975 and 1976 (78 male, 22 female).
• Exposure: Asbestos exposure assessed from detailed occupational, residential and family histories. Jobs included shipyard, asbestos factory, insulation, hessian sack-repair factory, gas-mask factory, docks and Navy. Lung burden was measured as light-visible fibres (coated and uncoated) per gram of dried lung, counting only fibres over 6 microns long. These were nearly always amphibole asbestos.
• Main results:
  • Mesothelioma series: of 88 patients with a history of asbestos exposure, all but one had over 20 000 fibres per gram of dried lung.
  • Mesothelioma series: 73 patients (83%) with a history of asbestos exposure had over 100 000 fibres per gram.
  • Mesothelioma series: 23 of these patients (26%) had some histological asbestosis, and most lungs with asbestosis contained over 3 million fibres per gram.
  • Mesothelioma series: the seven patients with no credible history of asbestos exposure all had under 40 000 fibres per gram; six had under 20 000, and no fibres were seen in two. The authors considered these spontaneous pleural mesotheliomas.
  • Mesothelioma series: one patient was the only home-environment asbestos-induced mesothelioma in the series. This was the son of a worker from a gas-mask factory where workers took crocidolite home to pack into canisters.
  • Control series: 57% had less than 10 000 fibres per gram of dried lung and 71% had less than 20 000.
  • Control series: 35% of male patients and 14% of female patients had over 20 000 fibres per gram.
  • Control series: pleural plaques were present in 55% of patients with over 20 000 fibres per gram and in 5.5% of those with fewer.
  • Lung cancer series: 57% of patients had less than 10 000 fibres per gram of dried lung and 80% had less than 20 000. No asbestosis was seen in any case.
  • 95% of patients with asbestos-induced mesotheliomas had over 50 000 fibres per gram in the base of a lower lobe, compared with 15% of the control series.
  • Among the 73 control and lung cancer patients who had lived most of their lives in one Merseyside district, mapping of homes showed no concentration of high-count cases near docks and shipyards. Most high-count cases near these areas were explained by the patients' jobs.
• The authors' conclusion: The authors concluded that there is a definite dose relationship between asbestos exposure and mesothelioma. They also concluded that 'sub-asbestosis' levels of asbestos exposure do not contribute to lung cancer in people not subjected to industrial asbestos exposure.
• Limitations the authors state:
  • Only light-visible fibres were counted. Fibres too fine for light microscopy were not counted because this was beyond the authors' resources.
  • Finer chrysotile fibres were very difficult to see, so the counted fibres were nearly all amphibole.
  • In the control series it was not possible to assess any influence of home environment on fibre levels.
  • In the lung cancer series the surgeons usually did not see or comment on pleural plaques.
  • The 7% of mesotheliomas judged spontaneous is much lower than their true incidence, because spontaneous mesotheliomas are not always reported to the coroner.
  • The study does not answer whether asbestos workers can develop lung cancer from asbestos without first having asbestosis.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Lung Cancer, Thorax, Pleural Plaques, Asbestos Exposure, Mesothelioma.

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• Correlation between fibre content of the lungs and disease in naval dockyard workers — J.C. Wagner, C.B. Moncrieff, et al. (1986)
• Correlation between fibre content of lung and disease in east London asbestos factory workers — R.M. Rudd (1989)
• Environmental exposure to asbestos and other inorganic fibres using animal lung model — E. Fornero, E. Belluso, et al. (2009)
• Five years update on relationships between malignant pleural mesothelioma and exposure to asbestos and other elongated mineral particles — P. Andujar, A. Lacourt, et al. (2016)
• Relationship of mortality, occupation, and pulmonary diffusing capacity to pleural thickening in the First National Health and Nutrition Examination Survey — D.P. Loomis, G.W. Collman, et al. (1989)

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