Cytotoxic effects of aramid fibres on rat pulmonary macrophages: comparison with chrysotile asbestos

Our plain-English summary of Cytotoxic effects of aramid fibres on rat pulmonary macrophages: comparison with chrysotile asbestos, by J. Dunnigan, D. Nadeau, D. Paradis (Toxicology Letters, 1984).

The study

• Authors: J. Dunnigan, D. Nadeau, D. Paradis
• Journal: Toxicology Letters
• Published: 1984;20(3):277-82
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aramid fibres have been proposed as a substitute for many asbestos uses. Although dimensional characteristics of aramid fibres vary with the type of application, some of the commercial grades proposed contain fibres whose geometry is clearly in a range where biological reactivities have been reported for other natural or man-made fibres. We wish to report that short aramid fibres, when tested on cultures of rat pulmonary alveolar macrophages (PAMs), induce the commonly recognized signs of a cytotoxic effect, that is: leakage of cytoplasmic and lysosomal marker enzymes, concomittant with a decreased ATP cell content.

In plain English

In this laboratory study, the authors tested whether short aramid fibres, proposed as a substitute for asbestos, damage rat lung cells in a dish. They extracted short fibres from a commercial grade of Kevlar 979 dry pulp and compared them with the UICC B Canadian chrysotile asbestos standard. Lung immune cells called pulmonary alveolar macrophages were taken from adult male Long-Evans rats and exposed to the fibres for 18 hours. Some cells were used freshly harvested and some after being kept in culture. The authors measured leakage of two cell enzymes and the cells' ATP content, which are common signs of cell damage. Of 141 aramid fibres counted, 90% were shorter than 5 micrometres and thinner than 0.25 micrometres. With freshly harvested cells, the response to chrysotile and to aramid was essentially identical. With cultured cells, the damage was even higher with aramid than with chrysotile. The authors cautioned that these results do not show aramid fibres would cause disease in living animals until such data exist. They concluded that the fibres should not be considered biologically inert.

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 (in vitro) cell experiment comparing short aramid fibres with chrysotile asbestos on rat lung macrophages
• Who was studied: Pulmonary alveolar macrophages (lung immune cells) obtained by lung washing from adult male Long-Evans black hooded rats, tested both freshly harvested and after culture. Results were means of at least 3-4 separate experiments. The number of rats is not stated.
• Exposure: Short aramid fibres extracted from commercial grade Kevlar 979 Dry Pulp (Du Pont), compared with UICC B Canadian chrysotile. Cells were incubated with the fibres for 18 hours. Fibre amounts are described only as 'the indicated quantities' and are not given in the text.
• Main results:
  • Of the aramid test fibres counted (N = 141), 90% were less than 5 micrometres long and less than 0.25 micrometres in diameter. Average length was 2.72 plus or minus 0.17 and average diameter 0.138 plus or minus 0.006 (mean plus or minus standard error).
  • With freshly harvested macrophages, the cell-damage responses (LDH and beta-galactosidase enzyme release, and ATP content) to chrysotile and to aramid fibres were essentially identical.
  • With cultured macrophages, the cell-damage response was even higher with aramid fibres than with chrysotile fibres.
• The authors' conclusion: The authors concluded that man-made organic fibres can induce a cytotoxic response in pulmonary macrophages. While the data need to be extended and confirmed in living animals, the authors stated that such fibres should not be considered biologically inert.
• Limitations the authors state:
  • The authors stated that the significance of the results is not easy to assess. They should not be taken to mean that aramid fibres would necessarily cause disease in living animals until in vivo data are available.

Topics

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

Medical terms in this study, explained in our Lexicon: Macrophage, Chrysotile, Alveolar Macrophage.

Related studies

• Pulmonary effects in rats inhaling size-separated chrysotile asbestos fibres or p-aramid fibrils: differences in cellular proliferative responses — D.B. Warheit, M.A. Hartsky, et al. (1996)
• Lung proliferative and clearance responses to inhaled para-aramid RFP in exposed hamsters and rats: comparisons with chrysotile asbestos fibers — D.B. Warheit, S.I. Snajdr, et al. (1997)
• In vitro biodegradation of chrysotile fibres by alveolar macrophages and mesothelial cells in culture: comparison with a pH effect — M.C. Jaurand, A. Gaudichet, et al. (1984)
• Cytotoxic effects of quartz and chrysotile asbestos: in vitro interspecies comparison with alveolar macrophages — J. Schimmelpfeng, A. Seidel (1991)
• A comparative study of the clearance of respirable para-aramid, chrysotile and glass fibres from rat lungs — A. Searl (1997)
• Comparison of phagocytosis of uncoated versus coated asbestos fibers by cultured human pulmonary alveolar macrophages — T.L. McLemore, V. Roggli, et al. (1981)

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