Mineral fiber concentration in lung tissue of mesothelioma patients in Finland

Our plain-English summary of Mineral fiber concentration in lung tissue of mesothelioma patients in Finland, by T. Tuomi, M. Segerberg-Konttinen, L. Tammilehto, et al (American Journal of Industrial Medicine, 1989).

The study

• Authors: T. Tuomi, M. Segerberg-Konttinen, L. Tammilehto, A. Tossavainen, E. Vanhala
• Journal: American Journal of Industrial Medicine
• Published: 1989;16(3):247-54
• Cited by: 37 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. 000171).

Abstract

The mineral fibers in lung tissue samples of 19 mesothelioma patients and 15 randomly selected autopsy cases were analyzed using low-temperature ashing, scanning electron microscopy (SEM) and x-ray microanalysis. The fiber concentration ranged from 0.5 to 370 million fibers per gram of dry tissue in the mesothelioma group and from less than 0.01 to 3.2 million fibers per gram of dry tissue in the autopsy group. In 80% of the mesothelioma patients and in 20% of the autopsy cases, the fiber concentration exceeded 1 million fibers per gram of dry tissue. Amphibole asbestos fibers predominated in both groups, and only a few chrysotile fibers were found. In the lungs of six mesothelioma patients, anthophyllite was the main fiber type. The overall analytical precision of sample preparation and fiber counting with SEM was 22%.

In plain English

This Finnish study measured mineral fibers in lung tissue from 19 male patients with pleural mesothelioma diagnosed at Helsinki University Central Hospital between January 1985 and August 1987. It compared them with a reference group of 15 consecutive autopsy cases from 1984. Tissue was ashed, and fibers were counted and identified by scanning electron microscopy and x-ray microanalysis. In the mesothelioma patients, concentrations ranged from 0.5 to 370 million fibers per gram of dry tissue, and 15 (79%) exceeded 1 million. The highest values were in two shipyard electricians and an insulator. In the reference group, concentrations ranged from less than 0.1 to 3.2 million, and three people exceeded 1 million. On average, the mesothelioma group had a 60-fold fiber content compared with the reference group. In the mesothelioma group, crocidolite, amosite and anthophyllite predominated, and few chrysotile fibers were found. The authors concluded that lung fiber levels indicated occupational asbestos exposure in about 80% of the mesothelioma patients, using 1 million fibers per gram as the limit. They noted that their method probably undercounted chrysotile and that their findings on anthophyllite were inconclusive.

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: Lung tissue fiber-burden study comparing mesothelioma patients with a reference group of autopsy cases, using low-temperature ashing, scanning electron microscopy (SEM) and x-ray microanalysis
• Who was studied: Mesothelioma group: 19 consecutive verified cases (male, pleural mesothelioma) diagnosed at Helsinki University Central Hospital, January 1985 to August 1987, mean age 57 (range 42-73). Reference group: 15 consecutive cases autopsied in 1984 at the Department of Forensic Medicine, Helsinki University, mean age at death 60 (range 36-83).
• Exposure: Mineral fiber concentration in lung tissue, with fiber type identified (crocidolite, amosite, anthophyllite, chrysotile, other silicates). Mesothelioma patients' occupations included shipyard electricians, painter and welder, an insulator, and construction workers. The authors gave particular attention to anthophyllite because of its wide use in Finland.
• Main results:
  • Mesothelioma group: fiber concentrations ranged from 0.5 to 370 million fibers per gram dry tissue; 15 of 19 patients (79%) had more than 1 million.
  • Mesothelioma group: the highest values, above 100 million fibers per gram dry tissue, were in two shipyard electricians and one insulator.
  • Reference group: concentrations ranged from less than 0.1 to 3.2 million fibers per gram dry tissue; 3 of 15 exceeded 1 million.
  • Reference group: asbestos fibers, mostly anthophyllite, made up 25 to 90% of all fibers.
  • On average, the mesothelioma group had a 60-fold fiber content in the lungs compared with the reference group.
  • Anthophyllite fibers were found in 70% of the mesothelioma patients, and anthophyllite was the main fiber type in six of them.
  • Fibers longer than 5 micrometres made up 35% of fibers in the mesothelioma group and 70% in the reference group.
  • In three mesothelioma patients sampled from all five lung lobes, the authors found no systematic pattern between lobes, although in one patient the highest lobe value was 8.5-fold the lowest.
  • Glass fibers or other man-made mineral fibers were not found in either group.
  • Overall analytical precision of sample preparation and SEM fiber counting was 22%.
• The authors' conclusion: The authors concluded that their results support the view that more than 1-2 million fibers per gram dry tissue (by SEM) indicates occupational asbestos exposure. Using 1 million fibers per gram as the limit, lung fiber concentrations indicated occupational asbestos exposure in about 80% of the mesothelioma patients.
• Limitations the authors state:
  • Chrysotile fibers are mostly too thin to identify by x-ray analysis with this method, so chrysotile may have been significantly undercounted.
  • A low chrysotile content does not necessarily mean there was no past chrysotile exposure.
  • Amosite and crocidolite were poorly distinguished because their x-ray spectra are almost similar.
  • Most fibers were thinner than 0.5 micrometres, so transmission electron microscopy would be needed for more reliable mineral identification.
  • The study was inconclusive on anthophyllite as a cause of mesothelioma because no mesothelioma patient had been exposed only to anthophyllite.
  • For the reference group, only the occupation at death or the last occupation of pensioners was available, with no fuller work history.

Topics

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

Medical terms in this study, explained in our Lexicon: Mineral Fiber, Mesothelioma, Autopsy, Low-Temperature Ashing, Scanning Electron Microscopy (SEM), Fibers Per Gram, Amphibole Asbestos, Chrysotile.

Related studies

• Asbestos exposure among Finnish lung cancer patients: occupational history and fiber concentration in lung tissue — A. Karjalainen, S. Anttila, et al. (1993)
• Pulmonary mineral fibers after occupational and environmental exposure to asbestos in the Russian chrysotile industry — A. Tossavainen, E. Kovalevsky, et al. (2000)
• The detection and localization of mineral fibers in tissue — C. Berkley, J. Churg, et al. (1965)
• Electron microscopy analysis of mineral fibers in human lung tissue — K.H. Friedrichs, M. Brockmann, et al. (1992)
• The association among ferruginous body, uncoated fibers, asbestos and non-asbestos fibers in lung tissue in terms of length — T. Suzuki, Y. Sakakibara, et al. (2016)
• Sectioning and imaging hard mineral fibres in biological tissues — N.F. Johnson, K. Ibe (1981)

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