Comparative toxicities of different forms of asbestos in a cell culture assay

Our plain-English summary of Comparative toxicities of different forms of asbestos in a cell culture assay, by B. Reiss, S. Solomon, J.H. Weisburger, et al (Environmental Research, 1980).

The study

• Authors: B. Reiss, S. Solomon, J.H. Weisburger, G.M. Williams
• Journal: Environmental Research
• Published: 1980;22(1):109-29
• Cited by: 37 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Three forms of Union Internationale Contre le Cancer (UICC) asbestos, amosite, crocidolite, and chrysotile, were assayed for their cytotoxicity (inhibition of colony formation) in cell culture. Using embryonic human intestine-derived (I-407) and adult rat liver-derived (ARL-6) epithelial cells, the order of cytotoxicity was chrysotile > amosite > crocidolite. All three asbestos types were more toxic to I-407 than to ARL-6 cells. Chrysotile, amosite, and crocidolite were also tested for inhibition of colony formation in cultures of mouse colon-derived epithelial-like (MCE-1) cells; these cells were more resistant than the I-407 cells to all three fiber types; although similar to the ARL-6 cells in sensitivity to chrysotile and amosite, the MCE-1 cells were more sensitive to crocidolite then the ARL-6 cells. Leaching of the three asbestos forms for 3 days in sterile deionized water did not appreciably affect the cytotoxicity of I-407 or ARL-6 cells. Leaching in hydrochloric acid, however, greatly decreased the cytotoxicity of chrysotile on these cells and particularly in cultures of ARL-6 cells slightly increased the cytotoxicity of amosite and crocidolite. Leaching in deionized water altered the composition of the asbestos as revealed by release of substantial levels of Mg2+ and Ca2+ into the leaching fluid. Greater titers of these ions were released during leaching in hydrochloric acid.

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

In plain English

This was a laboratory study of cells in culture, not people. The authors compared how toxic UICC standard reference samples of chrysotile, amosite and crocidolite were to human embryonic intestine-derived epithelial cells (I-407), adult rat liver-derived epithelial cells (ARL-6) and mouse colon-derived epithelial-like cells (MCE-1), which had not been fully characterized. Toxicity was measured as how much the asbestos reduced the cells' ability to form colonies. Chrysotile was most toxic, then amosite, then crocidolite; the authors described chrysotile as approximately tenfold more toxic than the amphiboles. The rat liver cells needed at least fivefold higher concentrations than the human intestinal cells for a similar effect. Soaking the fibers in water for 3 days did not appreciably change their toxicity, although it changed their chemistry. Soaking them in 5 N hydrochloric acid made chrysotile significantly less toxic and the amphiboles slightly more toxic. The authors concluded that their assay was a rapid and reliable way to measure the effect of asbestos on colony formation. They noted that some growth limitation from non-toxic effects of the fibers may still have occurred.

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 cell culture experiment (in vitro cytotoxicity assay measuring inhibition of colony formation)
• Who was studied: Three cell lines: human embryonic intestine-derived epithelial I-407 cells, adult rat liver-derived epithelial ARL-6 cells, and mouse colon-derived epithelial-like MCE-1 cells (isolated in the authors' laboratory and not yet fully characterized); no human subjects
• Exposure: UICC standard reference samples of Canadian chrysotile B, crocidolite and amosite, applied to cells (usually for 3 days), either unleached or after leaching in sterile deionized water or 5 N hydrochloric acid
• Main results:
  • In I-407 and ARL-6 cells, inhibition of colony formation depended on dose and duration, and the order of toxicity was chrysotile, then amosite, then crocidolite
  • Across the cell lines, chrysotile was about tenfold more toxic than the amphiboles (amosite and crocidolite)
  • ARL-6 (rat liver) cells needed at least fivefold higher asbestos concentrations than I-407 (human intestine) cells for comparable inhibition
  • MCE-1 (mouse colon) cells were less sensitive than I-407 cells to all fiber types. They were similar to ARL-6 cells for chrysotile and amosite but more sensitive than ARL-6 cells to crocidolite
  • Fibers stuck to the culture flask surface in the order amosite, then crocidolite, then chrysotile. Amosite added at seeding inhibited colony formation more than amosite added 24 hours after seeding
  • Cells that survived a first 6-day exposure usually showed greater toxicity after a second exposure, so survivors were not an inherently resistant group
  • Leaching all three fiber types in sterile deionized water for 3 days did not appreciably change their toxicity
  • Water leaching nonetheless released magnesium and calcium ions from the fibers
  • Leaching in hydrochloric acid released more of these ions than water leaching
  • Chrysotile leached in 5 N hydrochloric acid was significantly less toxic than unleached or water-leached chrysotile
  • Acid-leached amphiboles were slightly more toxic than water-leached amphiboles, particularly to ARL-6 cells
• The authors' conclusion: The authors concluded that their colony-formation assay is a rapid and reliable method for quantifying the inhibitory effect of asbestos on mammalian cells
• Limitations the authors state:
  • Even with fibers added 24 hours after seeding, some growth limitation from non-toxic effects of the fibers may still have occurred
  • The MCE-1 mouse colon cell line had not been fully characterized
  • Only magnesium and calcium were measured in the leaching fluids. A full analysis would be needed to identify an agent contributing to chrysotile toxicity

Topics

Medical terms in this study, explained in our Lexicon: UICC, Amosite, Crocidolite, Chrysotile.

Related studies

• Comparative toxicities of different forms of asbestos on rat pleural mesothelial cells — M.C. Jaurand, I. Bastie-Sigeac, et al. (1983)
• Absence of mutagenic activity of three forms of asbestos in liver epithelial cells — B. Reiss, S. Solomon, et al. (1982)
• The activity of environmental samples in a cell culture test for asbestos toxicity — B. Reiss, J.R. Millette, et al. (1980)
• Diagnosis of asbestosis by a time expanded wave form analysis, auscultation and high resolution computed tomography: a comparative study — N. al Jarad, B. Strickland, et al. (1993)
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• Validity of the Lymphocyte Cytokinesis-Block Micronucleus Assay (L-CBMN) as biomarker for human exposure to chemicals with different modes of action: A synthesis of systematic reviews — M. Kirsch-Volders, M. Fenech, et al. (2018)

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