Occupational exposure to asbestos as evaluated from work histories and analysis of lung tissues from patients with mesothelioma

Our plain-English summary of Occupational exposure to asbestos as evaluated from work histories and analysis of lung tissues from patients with mesothelioma, by T. Tuomi, M.S. Huuskonen, L. Tammilehto, et al (British Journal of Industrial Medicine, 1991).

The study

• Authors: T. Tuomi, M.S. Huuskonen, L. Tammilehto, E. Vanhala, M. Virtamo
• Journal: British Journal of Industrial Medicine
• Published: 1991;48(1):48-52
• Cited by: 30 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. 003764).

Abstract

The past occupational exposure to asbestos of 23 patients with mesothelioma (21 men and two women) has been evaluated by a personal interview of their work history and by determination of the fibre burden in their lung tissue with scanning electron microscopy (SEM) and x ray microanalysis. According to the work history, nine patients (39%) had definitely been or probably been exposed to asbestos, six patients (26%) had had possible exposures, and eight patients (35%) unlikely or unknown exposure to asbestos. The two female patients were in the unknown exposure category. The fibre concentrations in the patients' lung tissue ranged from less than 0.1 million to 370 million fibres (f) per g dry tissue. Concentrations of over one million f per g dry tissue were found in 15 patients (65%). The lung fibre concentrations of all nine male office workers analysed for reference were less than one million f per g dry tissue. Seventy eight per cent of the patients with mesothelioma had at least possible exposure according to their history of work or concentrations of more than one million f per g dry tissue.

In plain English

This Finnish study examined 23 patients with mesothelioma (21 men, two women) diagnosed at Helsinki University Central Hospital between 1985 and 1988. Each patient was interviewed about their work history. A panel that did not know the lung results then graded each patient's likely asbestos exposure. Lung tissue was examined by electron microscopy to count fibres, and nine male office workers served as a comparison group. From work histories, two patients were judged to have definite exposure, seven probable, six possible and eight unlikely or unknown. Patients' lung fibre levels ranged from less than 0.1 million to 370 million fibres per gram of dry tissue, with 15 patients (65%) above one million. All office workers were below one million. Fibres found included amosite, anthophyllite, crocidolite and tremolite. Combining both methods, 78% of patients had at least possible exposure. Three patients whose work histories placed them in the unlikely or unknown group had more than one million fibres per gram. On closer review, this was apparently due to work tasks that were normal but not typical. The authors concluded that a positive lung fibre result provides sufficient evidence of asbestos exposure even when the work history is negative or uninformative.

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: Comparison, in a series of mesothelioma patients, of exposure judged from interviewed work histories with lung fibre counts by scanning electron microscopy and x ray microanalysis, with a small reference group of office workers
• Who was studied: 23 patients with histologically confirmed mesothelioma (21 men, two women; mean age 56, range 39-72) diagnosed at Helsinki University Central Hospital, Finland, January 1985 to December 1988. Of the 48 diagnosed in that period, these were the ones who could be interviewed and had lung tissue available. 17 of them had been reported in an earlier study by the authors. The reference group was nine male office workers who had a necropsy in 1984 (mean age at death 53).
• Exposure: Past occupational, domestic and environmental asbestos exposure was assessed by interview and graded into four groups. Definite: asbestos mining, asbestos products, asbestos cement, insulation, demolition. Probable: shipyards, construction, metal workshops. Possible: various dusty trades. Unlikely or unknown. Lung fibre burden and fibre type were also measured.
• Main results:
  • By work history, the 23 patients were classed as: two (9%) definite exposure, seven (30%) probable, six (26%) possible, and eight (35%) unlikely or unknown. Both women were in the unlikely or unknown group.
  • Among exposed patients, the mean time from start of exposure to diagnosis was 35 years (range 21-55). The mean duration of exposure was 23 years (range 7-39).
  • In the patients, lung fibre concentrations ranged from less than 0.1 million to 370 million fibres per g dry tissue. Fifteen patients (65%) had more than one million fibres per g, and 10 (43%) had more than 10 million. The two highest values, over 100 million, were in two shipyard electricians.
  • Asbestos fibres (amosite, anthophyllite, crocidolite or tremolite) were found in 21 patients. Crocidolite and amosite were the main types in six patients (26%), anthophyllite in eight (35%), and both in seven (30%). One patient had no fibres, one had only silicate fibres, and no manmade fibres such as glass fibres were found.
  • In the nine male office workers, lung fibre concentrations ranged from less than 0.1 to 0.6 million fibres per g dry tissue.
  • Patients judged more likely to be exposed tended to have higher fibre concentrations. More than one million fibres per g dry tissue was found in all nine patients in the definite and probable groups combined, in 12 of 15 (80%) in groups I to III combined, in 3 of 6 (50%) in the possible group, and in 3 of 8 (38%) in the unlikely or unknown group.
  • Counting either at least possible exposure by work history or a lung concentration above one million fibres per g dry tissue, 78% of the patients had been exposed.
  • Three patients in the unlikely or unknown group had more than one million fibres per g. On closer review this was apparently due to normal but not typical work tasks: a caretaker (crocidolite found), a gardener (anthophyllite found) and a hardware salesman.
  • No occupational exposure was found for the two women, and their fibre concentrations were below one million per g. However, anthophyllite or tremolite fibres were found in their lungs. The authors suggested that families building their own houses could be a probable non-occupational source.
• The authors' conclusion: The authors concluded that lung fibre analysis improved the exposure assessment in six patients: it identified three further exposed cases and confirmed exposure in three others. They concluded that a positive lung fibre result provides sufficient evidence of asbestos exposure despite a negative or uninformative work history. They also stated that a work history strongly indicating exposure cannot be overruled by a negative lung fibre analysis, and that no lower limit of fibre burden can exclude occupational exposure in an individual case.
• Limitations the authors state:
  • Measured lung fibre concentration reflects lifelong retention, so recent exposures cannot be distinguished from past ones. Chrysotile is removed from the lungs more effectively than amphiboles, so a low chrysotile concentration does not rule out past chrysotile exposure.
  • Low fibre concentrations in some mesothelioma patients overlap with those in the general population, and the causal significance of a low concentration cannot be judged in individual cases.

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: Occupational Exposure, Mesothelioma, Work History, Scanning Electron Microscopy (SEM).

Related studies

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• Pulmonary mineral fibers after occupational and environmental exposure to asbestos in the Russian chrysotile industry — A. Tossavainen, E. Kovalevsky, et al. (2000)
• Mineral fiber concentration in lung tissue of mesothelioma patients in Finland — T. Tuomi, M. Segerberg-Konttinen, et al. (1989)
• Occupational life course and lung cancer risk in men. Findings from a socio-epidemiological analysis of job-changing histories in a case-control study — I. Jahn, U. Becker, et al. (1995)
• Asbestos exposure among Finnish lung cancer patients: occupational history and fiber concentration in lung tissue — A. Karjalainen, S. Anttila, et al. (1993)

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