Occupational asbestos exposure, lung-fiber concentration and latency time in malignant mesothelioma

Our plain-English summary of Occupational asbestos exposure, lung-fiber concentration and latency time in malignant mesothelioma, by G. Mowé, B. Gylseth, F. Hartveit, et al (Scandinavian Journal of Work, Environment & Health, 1984).

The study

• Authors: G. Mowé, B. Gylseth, F. Hartveit, V. Skaug
• Journal: Scandinavian Journal of Work, Environment & Health
• Published: 1984;10(5):293-8
• Cited by: 35 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000560).

Abstract

Mineral fiber concentration in lung tissue was analyzed by scanning electron microscopy in 73 males with malignant mesothelioma and in 36 referents who died of cardio- or cerebrovascular diseases. The investigation showed apparent differences in the median lung-fiber concentration between occupational groups with different levels of asbestos exposure, as judged from their occupational history. Thus the mineral fiber content in human lung tissue provides a useful indicator of cumulative asbestos exposure. There was also a statistically significant difference between the median lung-fiber concentration among mesothelioma cases with unlikely or unknown occupational asbestos exposure and the reference group. The latency times in 42 of the cases with definite or probable occupational asbestos exposure showed a log-normal distribution with a median of 37 years and a range of 19-68 years. No statistically significant correlation was found between the logarithm of the latency time and the logarithm of the lung-fiber concentration.

In plain English

The authors measured mineral fibers in lung tissue by scanning electron microscopy in 73 men with malignant mesothelioma, collected in Norway in 1978 to 1983, and in 36 referents who had died of cardio- or cerebrovascular disease. Cases were grouped by work history. Group I was insulation, asbestos-cement and chemical maintenance workers with high exposure to crocidolite and chrysotile. Group II was jobs with probable but generally lower exposure. Group III was unlikely or unknown exposure. Median lung-fiber concentration in group II was one-tenth that of group I and three times that of group III, and these differences were statistically significant. Group III also differed significantly from the referents (p less than 0.01). In 42 group I and II cases, time from first exposure to death had a median of 37 years (range 19 to 68). Its logarithm showed no statistically significant correlation with the logarithm of lung-fiber concentration (r = -0.088, p = 0.58). The authors concluded that lung-fiber concentration is a useful indicator of cumulative exposure when exposure has been to amphiboles, and that latency time is not correlated with it.

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 of lung-fiber concentrations, measured by scanning electron microscopy, between mesothelioma cases grouped by occupational history and a reference group, plus a correlation analysis of latency time against lung-fiber concentration
• Who was studied: 73 men with malignant mesothelioma whose lung tissue was supplied by Norwegian pathology departments, collected 1978 to 1983, and 36 referents who died of cardio- and cerebrovascular disease
• Exposure: Occupational asbestos exposure judged from work histories. Group I was insulation, asbestos-cement and chemical maintenance workers with evidence of high exposure to both crocidolite and chrysotile. Group II was occupations with a reported increased incidence of mesothelioma, where exposure was highly probable but generally lower and fiber types were not known. Group III was unlikely or unknown exposure. Latency time was defined as the time from the first year of asbestos-exposed employment to death.
• Main results:
  • The median lung-fiber concentration of group II was one-tenth of the group I median and three times the group III median; the differences were statistically significant.
  • The difference in median lung-fiber concentration between group III (unknown or unlikely exposure) and the reference group was statistically significant (p less than 0.01).
  • Five referents had worked in group II occupations, and all had fiber concentrations above 2.0 million per gram of dried tissue.
  • In 42 cases in groups I and II, latency times approximated a log-normal distribution with a median of 37 years and a range of 19 to 68 years.
  • The 42 cases were divided into three lung-fiber concentration subgroups (1.9 or less, 2.0 to 9.9, and 10 or more million fibers per gram of dried tissue). None of the variables (age and year at first exposure, latency time, age at death) differed statistically significantly between the subgroups.
  • No correlation was found between the logarithm of latency time and the logarithm of lung-fiber concentration (r = -0.088, p = 0.58). Latency time was correlated with year of first exposure (r = -0.9, p less than 0.001) and with age at first exposure (r = -0.65, p less than 0.001).
  • Lung-fiber concentrations of the cases overlapped those of the referents. In 12 cases the concentration was below one million per gram of dried tissue, and past exposure was unknown or unlikely in most of these.
• The authors' conclusion: The authors concluded that total lung-fiber concentration, analyzed by their method, is a useful indicator of cumulative asbestos exposure as judged from occupational history, provided the exposure has been to amphiboles. They also concluded that there is no correlation between latency time and total lung-fiber concentration in malignant mesothelioma.
• Limitations the authors state:
  • Occupational information was sometimes incomplete, so for some cases latency time could have been under- or overestimated, particularly in group III.
  • Sampling of lung tissue was not standardized; samples included both formaldehyde-preserved and paraffin-embedded material.
  • In an interlaboratory comparison, scanning electron microscopy detected only 40 to 50% of short, thin chrysotile fibers compared with transmission electron microscopy.
  • Fiber concentrations may vary from site to site in lung tissue, so low concentrations do not exclude past occupational asbestos exposure.

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: Asbestos Exposure, Latency, Mesothelioma, Mineral Fiber, Scanning Electron Microscopy (SEM), Occupational History.

Related studies

• Asbestos exposure among Finnish lung cancer patients: occupational history and fiber concentration in lung tissue — A. Karjalainen, S. Anttila, et al. (1993)
• Analysis of latency time and its determinants in asbestos related malignant mesothelioma cases of the Italian register — A. Marinaccio, A. Binazzi, et al. (2007)
• Hierarchical latency models for dose-time-response associations — D.B. Richardson, R.F. MacLehose, et al. (2011)
• Mineral fiber concentration in lung tissue of mesothelioma patients in Finland — T. Tuomi, M. Segerberg-Konttinen, et al. (1989)
• Asbestos fiber concentrations in the lungs of brake repair workers: commercial amphiboles levels are predictive of chrysotile levels — G.M. Marsh, A.O. Youk, et al. (2011)
• The analysis of asbestos count data with "nondetects": the example of asbestos fiber concentrations in the lungs of brake workers — M.M. Finkelstein (2013)

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