The in vitro cytotoxicity of asbestos fibers: I. P388D1 cells

Our plain-English summary of The in vitro cytotoxicity of asbestos fibers: I. P388D1 cells, by A. Wright, H. Cowie, I.P. Gormley, et al (American Journal of Industrial Medicine, 1986).

The study

• Authors: A. Wright, H. Cowie, I.P. Gormley, J.M. Davis
• Journal: American Journal of Industrial Medicine
• Published: 1986;9(4):371-84
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In this study, the cytotoxicity of 13 fibrous samples of known fiber number and dimensions has been established in P388D1 cells. The cells were exposed in vitro to dust concentrations of 10 or 50 micrograms/ml and, after incubation for 24 or 48 hours, any changes in cellular viability, lactate dehydrogenase, and glucosaminidase levels were determined. In general, there was a close association between the reduction in cellular viability and the loss of intracellular enzymes induced by each dust, the chrysotile asbestos samples proving more cytotoxic than the amphiboles. The cytotoxicity of the fibrous dusts was shown to be related to the number of fibers greater than 8 micron in length in the samples.

In plain English

This laboratory study tested how toxic 13 fibrous dusts were to P388D1 cells, a cell line with many macrophage-like characteristics. The samples included crocidolite, amosite, chrysotile, anthophyllite, tremolite, brucite and ceramic fiber, some in several forms. Cells received 10 or 50 micrograms per milliliter for 24 or 48 hours. Cell viability and two enzymes were measured, each as a percentage of the matching value in cultures given non-toxic titanium dioxide. The chrysotile samples were consistently more toxic than the amphiboles. After 48 hours at the higher dose, viability was 9.0 percent with UICC chrysotile and 62.6 percent with UICC crocidolite. Ceramic fiber was least toxic, though not significantly different from short-fiber amosite. Viability generally correlated best with the number of fibers longer than 8 micrometers. The authors concluded that such cell tests cannot yet be accepted as giving completely reliable predictions of fibrosis or cancer, but may prove useful for initial screening, especially considering fiber durability. They noted that chrysotile proving more harmful appears to contradict human epidemiology suggesting amphiboles are more dangerous, probably because chrysotile is cleared from lung tissue faster.

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: In vitro laboratory experiment (cell culture cytotoxicity assay)
• Who was studied: Cultures of P388D1 cells, a permanent cell line with macrophage-like characteristics, studied at the Institute of Occupational Medicine, Edinburgh. Each dust was tested on at least three separate occasions.
• Exposure: Thirteen fibrous dusts, each given at 10 or 50 micrograms per milliliter for 24 or 48 hours. The samples were UICC crocidolite, amosite and chrysotile A (as supplied and elutriated), plus elutriated UICC anthophyllite, ceramic fiber, long-fiber amosite, tremolite and brucite. The others were short-fiber amosite and superfine (SFA) chrysotile. Titanium dioxide served as the non-toxic control and quartz DQ12 as the toxic control.
• Main results:
  • Across doses and time points, the chrysotile samples were consistently more cytotoxic to P388D1 cells than the amphiboles.
  • UICC chrysotile at 50 micrograms per milliliter for 48 hours: cell viability was 9.0 plus or minus 8.5 percent of the titanium dioxide control.
  • UICC crocidolite at 50 micrograms per milliliter for 48 hours: cell viability was 62.6 plus or minus 10.2 percent of the titanium dioxide control.
  • Elutriated ceramic fiber showed the lowest cytotoxicity, but its results were not significantly different from those for short-fiber amosite.
  • Elutriated tremolite and anthophyllite had similar cytotoxicity, and both were significantly more toxic than the other amphibole samples.
  • Short-fiber amosite was consistently less cytotoxic than its long-fiber parent sample. The difference reached p less than 0.001 at 50 micrograms per milliliter for 48 hours.
  • Except at 10 micrograms per milliliter for 24 hours, cell viability was positively associated with intracellular LDH, intracellular glucosaminidase and total glucosaminidase (p less than 0.05).
  • The correlation between cell viability and the number of fibers above a given length generally reached a maximum at 8 micrometers.
  • For intracellular LDH at 48 hours, the best correlation was with fibers longer than 8 micrometers at both doses. At 24 hours the best correlation was with longer fibers, up to fibers longer than 20 micrometers at the 10 microgram dose.
  • For intracellular glucosaminidase at 50 micrograms per milliliter, the best correlations were with fibers longer than 8 micrometers. At 10 micrograms per milliliter the best correlation was with much shorter fibers, longer than 2 micrometers.
  • Elutriation of UICC crocidolite, amosite or chrysotile had only a small and not significant effect on fiber length distributions.
• The authors' conclusion: The authors concluded that in vitro testing of mineral dusts cannot yet be accepted as producing completely reliable predictions of fibrogenicity and carcinogenicity. They added that accumulating data suggest it may be useful for initial screening where many samples have to be examined, especially if the likely durability of the fibers is considered.
• Limitations the authors state:
  • The authors stated that differences in preparation, instruments and counting rules make fiber size and number results difficult to compare between laboratories.
  • The authors stated that the best correlation with fibers longer than 20 micrometers might be anomalous, because few such fibers were present in most samples.
  • The authors noted that it may be difficult to tell different biological hazards apart when only one cell line is used.
  • The authors noted that chrysotile proving more harmful than the amphiboles appears to contradict human epidemiology, which suggests amphiboles are more dangerous. They said this is probably explained by chrysotile being removed from lung tissue more rapidly.
  • In an addendum, the authors reported a change in the cell line after the study was completed. After more than 200 passages, the P388D1 cells began to show increased resistance to being killed by toxic dusts such as quartz.

Topics

Medical terms in this study, explained in our Lexicon: Lactate Dehydrogenase (LDH), Chrysotile, Amphibole Group.

Related studies

• Some observations on the in vitro cytotoxicity of chrysotile prepared by the wet dispersion process — I.P. Gormley, R.E. Bolton, et al. (1983)
• In vitro cytotoxicity and transforming potential of industrial carbon dust (fibers and particles) in syrian hamster embryo (SHE) cells — C. Darne, F. Terzetti, et al. (2010)
• In vitro cytotoxicity of asbestos and man-made vitreous fibers: roles of fiber length, diameter and composition — G.A. Hart, L.M. Kathman, et al. (1994)
• Role of fibre characteristics on cytotoxicity and induction of anaphase/telophase aberrations in rat pleural mesothelial cells in vitro: correlations with in vivo animal findings — M. Yegles, X. Janson, et al. (1995)
• Biological effects of naturally occurring and man-made fibres: in vitro cytotoxicity and mutagenesis in mammalian cells — R. Okayasu, L. Wu, et al. (1999)
• Enhancement by asbestos of oncogenesis by Moloney murine sarcoma virus in CBA mice — K. Kanazawa, T. Yamamoto, et al. (1979)

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