Solubility of asbestos and man-made mineral fibers in vitro and in vivo: its significance in lung disease

Our plain-English summary of Solubility of asbestos and man-made mineral fibers in vitro and in vivo: its significance in lung disease, by A. Morgan, A. Holmes (Environmental Research, 1986).

The study

• Authors: A. Morgan, A. Holmes
• Journal: Environmental Research
• Published: 1986;39(2):475-84
• Cited by: 40 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Work on the solubility of asbestiform minerals and of man-made mineral fibers, both in vitro and in vivo, is reviewed. The significance of solubility in determining the pathogenic potential of these materials is also discussed.

In plain English

This 1986 paper is a review, not a new study. The authors, at the Atomic Energy Research Establishment in Harwell, United Kingdom, reviewed laboratory and animal work, and studies of fibers from human lungs, on how asbestos and man-made mineral fibers dissolve and what this means for lung disease. In one rat study, in which chrysotile was injected into the pleural cavity rather than inhaled, as much as 35% of its magnesium dissolved in the first month, with much slower dissolution afterwards. Some iron leached from crocidolite, but the authors stated that the silicate part of amphibole fibers is insoluble in lung for all practical purposes. In rats, long glass fibers dissolved faster than short ones. In rats, rock wool fibers showed no significant diameter change at their centers after 18 months, but their ends were thinning, so slow dissolution did occur. The authors concluded that glass and rock wool fibers are much more soluble in vivo than amphibole fibers, and that this likely works against the malignant diseases amphiboles can cause. They said in vitro results should be treated with caution.

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: Review of published work on fiber solubility, with discussion of its significance for disease
• Who was studied: No new study population. The review covered published in vitro experiments, in vivo studies in rats, hamsters and rabbits, and studies of fibers recovered from human lung.
• Exposure: Chrysotile (serpentine asbestos); the amphiboles crocidolite, amosite and anthophyllite; and man-made mineral fibers made from glass, rock or slag, especially glass fibers and rock wool
• Main results:
  • Chrysotile in rats (Morgan et al., 1971, reviewed): the fibers were given by intrapleural inoculation, not by inhalation. As much as 35% of the magnesium dissolved in the first month, and dissolution was much slower thereafter.
  • Human lungs examined after death: chrysotile fiber numbers relative to amphibole fibers often did not match exposure history. The authors took this to imply that chrysotile is removed preferentially. They described the means of removal as still unresolved.
  • Amphiboles: iron was reported to leach from crocidolite. The authors stated that amphibole fibers persist in human lung years after exposure ends, which shows that their silicate structure is insoluble in lung for all practical purposes.
  • Glass fibers in rats (Morgan et al., 1982, reviewed; followed for up to 18 months): short fibers dissolved uniformly and relatively slowly. Fibers 30 and 60 micrometers long dissolved much more rapidly, and many had fragmented by the end.
  • Rock wool in rats (Morgan and Holmes, 1984, reviewed; given by intratracheal instillation): diameters were measured at the fibers' centers, and after 18 months there was no significant change in diameter.
  • In the same rock wool study, the fibers were becoming thinner at their ends than in the middle even after 6 months, so slow dissolution does occur.
  • In vitro (Förster, 1984, reviewed): the measured dissolution rates indicated that fine man-made fibers could dissolve completely after 1 to 2 years in a continuous-flow system.
  • The authors judged that glass and rock wool fibers are much more soluble in vivo than fibrous amphiboles. They added that glass appears more soluble than rock wool, but that this cannot be assumed for all glass fibers.
• The authors' conclusion: The authors concluded that the relative solubility of inhaled man-made mineral fibers likely mitigates against the malignant diseases of the lung, pleura and peritoneum that certain amphiboles can cause. They noted that thick fibers become thinner as they dissolve and may come to resemble the amphibole fibers associated with mesothelial tumours. However, these thin fibers may not last long enough in the lung to start a carcinogenic response.
• Limitations the authors state:
  • In vitro tests cannot reproduce the varying pH and complexing agents that fibers meet inside the lung, so their results should be treated with caution.
  • The comparison of glass with rock wool solubility rests on limited data.
  • The effect of fiber length on solubility seen in vivo cannot be reproduced in vitro.

Topics

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

Medical terms in this study, explained in our Lexicon: Mineral Fiber, Asbestiform.

Related studies

• Solubility of chrysotile asbestos and basalt fibers in relation to their fibrogenic and carcinogenic action — F.M. Kogan, O.V. Nikitina (1994)
• Correlation of in vitro and in vivo methods by means of mass dose and fiber distribution for amosite and fibrous ferroactinolite — D.L. Coffin, L.D. Palekar, et al. (1983)
• Solubility of rockwool fibres in vivo and the formation of pseudo-asbestos bodies — A. Morgan, A. Holmes (1984)
• Lung dust analysis in the assessment of past exposure of man-made mineral fibre workers — J.C. McDonald, B.W. Case, et al. (1990)
• Man-made vitreous fibers and workers' health. An overview of the epidemiologic evidence — R. Saracci, L. Simonato (1982)
• Measurement and analysis of chemically changed mineral fibers after experiments in vitro and in vivo — K.R. Spurny (1983)

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