Induction of chromosome changes in Chinese hamster cells by exposure to asbestos fibres

Our plain-English summary of Induction of chromosome changes in Chinese hamster cells by exposure to asbestos fibres, by A. Sincock, M. Seabright (Nature, 1975).

The study

• Authors: A. Sincock, M. Seabright
• Journal: Nature
• Published: 1975;257(5521):56-8
• Cited by: 113 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This was a laboratory experiment on cultured Chinese hamster cells from the CHO-K1 cell line, not a study of people. The authors grew the cells with one of four dusts at 0.01 mg per ml (SFA chrysotile asbestos, UICC crocidolite asbestos, glassfibre or glass powder) alongside unexposed control cultures. After 48 hours or 5 days they examined 100 dividing cells from each culture. They repeated the experiment with a fixation method that avoided centrifugation and the use of proteolytic (protein-digesting) enzymes for detaching cells. Chromosome changes were largely restricted to asbestos-exposed cells. After 48 hours, abnormal cells made up 59 percent (55 with the second method) of chrysotile-exposed cells and 65 percent (56) of crocidolite-exposed cells, against 3 to 5 percent for the glass dusts and controls. Only asbestos-exposed cultures showed chromosome-type breaks and rearrangements. Longer exposure seemed to have little effect, except a possible trend toward more cells with fragments in the 5-day chrysotile group. Asbestos fibres pre-soaked in culture medium produced fewer abnormalities. The authors called this a preliminary first stage toward a laboratory screening test for cancer-causing materials.

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) experiment on cultured Chinese hamster cells
• Who was studied: Chinese hamster cells cloned from the CHO-K1 line (American Type Culture Collection)
• Exposure: SFA chrysotile asbestos and UICC crocidolite asbestos at 0.01 mg per ml. Glassfibre and glass powder were used as comparison dusts at the same concentration, and unexposed cultures served as controls. Exposure lasted 48 hours or 5 days.
• Main results:
  • Chromosome (karyotypic) changes were largely restricted to the cells exposed to asbestos.
  • At 48 hours, with 100 cells scored from each culture, the percentage of abnormal cells was 59 (55 by in situ fixation) for SFA chrysotile, 65 (56) for UICC crocidolite, 3 (5) for glassfibre, 4 (4) for glass powder and 4 (4) for unexposed controls.
  • Some cells from asbestos-treated cultures showed chromosome-type breaks and rearrangements. None were found in glass-treated cultures or unexposed controls.
  • In glass-exposed cultures, polyploid cells were mostly the only unusual cells, and they were no more common than in unexposed controls.
  • Extending exposure from 48 hours to 5 days seemed to have little effect on abnormalities. The possible exception was the 5-day SFA chrysotile group, which showed an increased trend toward cells with fragments.
  • In additional experiments, asbestos fibres were preincubated in culture medium for a short period before they came into contact with cells. These fibres produced fewer abnormalities.
  • At collection, all cultures had plating efficiencies above 89% and viabilities above 85%.
  • The in situ fixation method avoided centrifugation and proteolytic enzymes for cell detachment. Its results correlated closely with those from the standard method.
• The authors' conclusion: The authors concluded that asbestos fibres in the culture produced multiple abnormalities at both chromatid and chromosome levels, and that this happened specifically with asbestos rather than glass dusts. They described this as a preliminary first stage toward an in vitro screening test for asbestos and other carcinogenic materials.
• Limitations the authors state:
  • The authors stated that the chromosome-type changes might reflect selection of pre-existing cell clones, and that this was still being examined in further experiments.
  • The authors suggested that components of the culture medium, such as serum protein, may interact with asbestos and alter the effective dose and exposure period.

Related studies

• Genetic effects of crocidolite asbestos in Chinese hamster lung cells — S.L. Huang, D. Saggioro, et al. (1978)
• A comparison of the cytogenetic response to asbestos and glass fibre in Chinese hamster and human cell lines. Demonstration of growth inhibition in primary human fibroblasts — A.M. Sincock, J.D. Delhanty, et al. (1982)
• Metsovo-tremolite asbestos fibres: in vitro effects on mutation, chromosome aberration, cell transformation and intercellular communication — K. Athanasiou, S.H. Constantopoulos, et al. (1992)
• Induction of micronuclei, hyperdiploidy and chromosomal breakage affecting the centric/pericentric regions of chromosomes 1 and 9 in human amniotic fluid cells after treatment with asbestos and ceramic fibers — E. Dopp, M. Schuler, et al. (1997)
• An early, nonrandom karyotypic change in immortal Syrian hamster cell lines transformed by asbestos: trisomy of chromosome 11 — M. Oshimura, T.W. Hesterberg, et al. (1986)
• Chrysotile and rock wool fibers induce chromosome aberrations and DNA damage in V79 lung fibroblast cells — Y. Cui, J. Ma, et al. (2018)

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