The effect of asbestos on tissue cultures; a comparative study with quartz and coal dust

Our plain-English summary of The effect of asbestos on tissue cultures; a comparative study with quartz and coal dust, by T.H. Belt, I. Friedmann, E.J. King (The Journal of Pathology and Bacteriology, 1947).

The study

• Authors: T.H. Belt, I. Friedmann, E.J. King
• Journal: The Journal of Pathology and Bacteriology
• Published: 1947;59(1-2):159-64
• Cited by: 9 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. 002882).

Abstract

1. Phagocytosis, even of small particles of asbestos, took place slowly in tissue cultures and a considerable portion of the asbestos dust, approximately 50 per cent., remained untouched, though within range of phagocytes throughout the experiments. Compared with coal or quartz, asbestos was less readily phagocytosed, particle size being equal.
2. Asbestos particles in small amount had little or no toxic effect on living cells in tissue cultures. The growth of fibroblasts was neither retarded nor accelerated and no necrosis of cells was observed as a result of contact with asbestos particles, while fatty change appeared to occur more slowly in asbestos phagocytes than in coal phagocytes.
3. Asbestos particles underwent no visible change, and in particular no visible diminution in size, after having been ingested by phagocytes for as long as 5 weeks.
4. The motility of wandering phagocytes was decreased after the ingestion of asbestos particles. This effect, not necessarily of a toxic character, may be deleterious in the case of cells within the lungs, since it tends to restrict the migration of cells and so favour the retention of particles within the lungs.
5. Particles under 5 µm in length restricted cellular motility more than larger particles, for the reason that they were more readily phagocytosed. It would seem that wandering phagocytes are rarely able to ingest particles larger than 10 µm. Giant cells sometimes formed in tissue cultures, apparently by fusion of two or more ordinary phagocytes, and were then able to engulf larger particles or clusters of particles.
6. There was no evidence of the formation of asbestos bodies in these experiments, nor have we noted the appearance of brown granular pigment like that seen in the lungs of experimental animals.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This laboratory study came from the British Postgraduate Medical School, London. The researchers added Canadian asbestos, quartz, steam coal and anthracite dusts to tissue grown in culture. Tissues included chick and rat embryo lung or heart, human fetal lung, and white blood cells. Across 28 experiments, about 500 slide and 50 flask cultures were examined. Scavenger cells (phagocytes) took up coal and quartz readily but asbestos slowly, and about 50 per cent of the asbestos stayed untouched. Only short asbestos fibres were taken up to any considerable extent. The authors saw no necrosis (cell death). Growth did not differ appreciably from undusted controls, though heavier dusting sometimes restricted growth, apparently mechanically rather than chemically. Asbestos- or quartz-laden cells stayed in the tissue or, if they migrated outwards, never went as far as coal-laden cells. Fibres showed no visible change over as long as 5 weeks, and there was no evidence of asbestos bodies forming. The authors said such short experiments bear little relation to human asbestosis. They concluded that tissue culture had not improved understanding of how asbestosis arises.

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: Laboratory tissue culture experiment (in vitro) comparing the effects of asbestos, quartz and coal dusts on cultured cells
• Who was studied: Cultured tissues: lung or heart of 11-12 day chick embryos, lung or heart of rat embryos, human fetal lung from Caesarean section cases, and white blood cells (leucocytes) from fowl, rat or human blood. About 500 slide cultures and 50 flask cultures in 28 experiments, at the British Postgraduate Medical School, London.
• Exposure: Canadian asbestos in two sizes (printed as 2.5 and 5, most likely microns), compared with quartz, steam coal "S4" and anthracite "A1". Dust was applied as a settling cloud, dried onto a coverslip, injected into embryonic lung tissue (1 ml of fluid containing 10 mg of dust), or injected into the trachea of rat embryos. Undusted tissue fragments served as controls.
• Main results:
  • In the asbestos cultures, phagocytosis was slow and approximately 50 per cent of the asbestos dust remained untouched although within range of phagocytes. Asbestos was less readily phagocytosed than coal or quartz.
  • Coal and quartz were easily engulfed and reached a high rate of phagocytosis after 48 hours. The authors saw no appreciable difference between quartz and coal at this stage.
  • Large coal clumps and quartz crystals were readily engulfed, but only short asbestos fibres were taken up to any considerable extent.
  • Growth of the dusted cultures (coal, quartz or asbestos) was not appreciably different from the undusted controls. More heavily dusted cultures showed restriction and sometimes suppression of growth, which seemed mechanical rather than chemical.
  • No necrosis was seen. Fatty change appeared less advanced in asbestos-laden cells than in coal-laden cells, which often broke down.
  • Coal-laden cells moved out of the tissue to a considerable distance. Cells containing quartz or asbestos stayed in the tissue, and when they sometimes did migrate outwards they never reached the same distance.
  • Asbestos particles showed no visible change, including no visible reduction in size, after being inside phagocytes for as long as 5 weeks.
  • The authors found no evidence of asbestos bodies forming in these experiments.
• The authors' conclusion: The authors concluded that tissue culture experiments had not led to a better understanding of how asbestosis arises in the human lung. They suggested that the reduced motility of asbestos-laden phagocytes, not necessarily toxic, may tend to favour retention of particles within the lungs.
• Limitations the authors state:
  • Tissue culture experiments last only a very short time and bear little relation to naturally occurring pulmonary asbestosis.
  • The apparent lack of toxic effect in culture gives an impression of harmlessness. The authors say this is contrary to the known danger of asbestos dust inhaled by people over long periods.
  • Asbestos was hard to cut to size, so even the smaller-size dust contained a number of long fibres.

Topics

Medical terms in this study, explained in our Lexicon: Phagocytosis, Fibroblast, Necrosis, Asbestos Bodies.

Related studies

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• Toxicity of cell culture medium due to filtration through asbestos pads — W. House (1964)
• The cytotoxic effects of asbestos and other mineral dust in tissue culture cell lines — M. Chamberlain, R.C. Brown (1978)
• Does a Heavy Fe-Isotope Composition of Akilia Quartz-Amphibole-Pyroxene Rocks Necessitate a BIF Origin? — M.J. Whitehouse, R. Schoenberg, et al. (2015)
• Reaction of mineral dusts with primary lung fibroblast cultures — R.J. Richards, J. Hunt (1983)
• Occupational exposures to fibers and quartz at 19 crushed stone mining and milling operations — G.J. Kullman, A.L. Greife, et al. (1995)

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