Coated and uncoated lung mineral fibres in subjects with and without pleural plaques at autopsy

Our plain-English summary of Coated and uncoated lung mineral fibres in subjects with and without pleural plaques at autopsy, by A. Andrion, D. Bellis, E. Bertoldo, et al (Pathology, Research and Practice, 1984).

The study

• Authors: A. Andrion, D. Bellis, E. Bertoldo, F. Mollo
• Journal: Pathology, Research and Practice
• Published: 1984;178(6):611-6
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The lung concentration of coated and uncoated mineral fibres of more than 10 micron in length was determined by light microscopy in 57 autopsied subjects (23 out of which professionally exposed to asbestos) with pleural plaques but no other asbestos-related diseases. Comparisons were made with 57 controls matched for sex, age and smoking habits, who did not show any asbestos-associated diseases or history of previous occupational exposure. Subjects with pleural plaques had a median concentration of coated fibres consistently greater than that observed in those without. However, no substantial differences were found between the two studied groups when uncoated and total fibres were considered. The present study suggests that the factors related to the fibre coating and to the pleural plaque formation may be indirectly connected, but not necessarily restricted to the number and nature of the fibres, or to the professional or environmental conditions of exposure.

In plain English

This autopsy study from Turin, Italy, used light microscopy to count coated fibres (asbestos bodies) and uncoated mineral fibres 10 micrometres or longer in lung tissue. It compared 57 adults whose only possibly asbestos-related change was pleural plaques with 57 controls matched for sex, age and smoking habit. The controls had no plaques, no asbestos-related disease and no documented history of occupational asbestos exposure. Occupational histories showed asbestos exposure in 23 of the 57 people with plaques. Coated fibres were found in 53/57 (93%) people with plaques and in 17/57 (30%) controls. The median coated fibre count per gram of dry lung was 381 in people with plaques and 0 in controls. Median uncoated (10858 vs 11017) and total (11 811 vs 11 032) fibre counts were nearly the same. The authors concluded that the factors behind fibre coating and plaque formation may be indirectly connected, but not necessarily restricted to the number and nature of the fibres, or to the occupational or environmental conditions of exposure. They noted that counting only long fibres probably excluded most chrysotile.

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: Autopsy study comparing people with pleural plaques against matched controls (lung fibre counts by light microscopy of digested lung tissue)
• Who was studied: 57 autopsied adults (53 men and 4 women) whose only possibly asbestos-related change was pleural plaques (20 grade I, 37 grade II). They were compared with 57 matched controls who had no plaques, no asbestos-related disease and no documented history of occupational asbestos exposure. Both groups were selected from 898 autopsied patients in Turin, North-western Italy (September 1977 to May 1979 and June 1980 to June 1981). Mean age was 65 in both groups.
• Exposure: Lung burden of coated fibres (asbestos bodies) and of uncoated mineral fibres 10 micrometres or longer; fibre types were not identified. Occupational asbestos exposure was documented in 23/57 (40%) of the plaque group. Their jobs included construction work handling asbestos-cement materials, car mechanics (brake and clutch repair), maintenance and repair of heating equipment, and work in friction material industries. No miners, millers or textile asbestos workers were included.
• Main results:
  • Coated fibres were found in the lungs of 53/57 (93%) subjects with plaques and of 17/57 (30%) subjects without plaques.
  • More than 100 coated fibres per gram of dried lung were found in 45/57 (79%) of the plaque group and in 10/57 (18%) of controls.
  • Among controls, 40/57 (70%) had no coated fibres in the lungs.
  • The median count of coated fibres per gram dry weight was 381 in subjects with plaques.
  • The median count of coated fibres per gram dry weight was 0 in the group without plaques.
  • Within the plaque group, median coated fibre counts did not differ substantially by plaque severity or occupational exposure. The exception was occupationally exposed subjects with grade II plaques, whose median was twice that of occupationally exposed subjects with grade I plaques (809 vs 447 per gram).
  • Median uncoated fibre counts per gram dry weight were 10858 in subjects with plaques and 11017 in those without. Median total fibre counts were 11 811 and 11 032 respectively.
  • In both groups, the number of uncoated fibres did not rise with the number of coated fibres.
• The authors' conclusion: The authors concluded that the factors related to fibre coating and to pleural plaque formation may be indirectly connected. They added that these factors are not necessarily restricted to the number and nature of the fibres, or to the professional or environmental conditions of exposure.
• Limitations the authors state:
  • Only fibres longer than 10 micrometres were counted, so most chrysotile fibres were probably excluded.
  • The uncoated fibres counted were probably a mix of asbestos and non-asbestos fibres.
  • Light microscopy cannot give definite conclusions about which fibre types were present.
  • Occupational histories were taken from relatives and work colleagues and may be inaccurate, especially for brief or long-past exposure. About half of the plaque cases with more than 100 coated fibres per gram had no documented occupational exposure.
  • Optical (light microscope) counts give only an approximate indication of actual fibre concentration.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Autopsy, Habit, Occupational Exposure.

Related studies

• Relationship between number of asbestos bodies in autopsy lung and pleural plaques on chest X-ray film — T. Kishimoto, T. Ono, et al. (1989)
• Mineral particles in the lungs of subjects resident in the Rome area and not occupationally exposed to mineral dust — L. Paoletti, D. Batisti, et al. (1987)
• Pleural plaques and exposure to mineral fibres in a male urban necropsy population — A. Karjalainen, P.J. Karhunen, et al. (1994)
• Lung asbestos bodies and pulmonary cancer in subjects without occupational exposure — A. Andrion, E. Pira, et al. (1982)
• Analysis and identification of elongated mineral particles in road coated aggregates — E. Leocat, C. Rielland, et al. (2018)
• The natural course of lung function decline in asbestos exposed subjects with pleural plaques and asbestosis — M. Barnikel, P.M. Million, et al. (2019)

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