The in vitro genetic effects of fibrous erionite and crocidolite asbestos

Our plain-English summary of The in vitro genetic effects of fibrous erionite and crocidolite asbestos, by K.T. Kelsey, E. Yano, H.L. Liber, et al (British Journal of Cancer, 1986).

The study

• Authors: K.T. Kelsey, E. Yano, H.L. Liber, J.B. Little
• Journal: British Journal of Cancer
• Published: 1986;54(1):107-14
• Cited by: 43 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Epidemiologic evidence has recently identified an association between an endemic outbreak of pleural and peritoneal mesothelioma in the Urgup region of Turkey and exposure to zeolite fibres. This malignancy is usually associated with exposure to asbestos dusts whose mineralogical characteristics differ from those of zeolites. The present study further defines the in vitro biologic activity of erionite, a common zeolite fibre found in the Urgup region of Turkey. Both erionite and crocidolite asbestos fibres were clastogenic in synchronous Chinese hamster ovary (CHO) fibroblasts. Both fibres also altered CHO ploidy. Erionite, unlike crocidolite or Min-U-Sil quartz, caused a slight increase in sister chromatid exchanges in synchronous CHO cells. Neither erionite nor crocidolite was mutagenic in a human lymphoblastoid cell line. Erionite fibres thus produced in vitro cytogenic changes similar to those caused by asbestiform mineral dusts and, like asbestos fibres, did not induce mutations in human lymphoblastoid cells.

In plain English

This was a laboratory study of cells grown in culture, not of people. The authors compared erionite, a fibrous zeolite mineral that earlier studies linked to mesothelioma in the Karain area of Turkey, with UICC crocidolite asbestos and non-fibrous Min-U-Sil quartz. Because enriched Karain erionite was not available, they used erionite from Rome, Oregon (USA). In Chinese hamster ovary (CHO) cells, erionite significantly raised sister chromatid exchanges (a type of chromosome change) in each of four experiments, by 17% to 26% above baseline. Crocidolite did so at one dose in one experiment, and quartz did not. Both fibers caused low levels of chromosome damage and increased the share of cells with doubled chromosome sets; quartz did neither. In a human cell line, neither fiber caused mutations at two genetic sites, while X-rays did. The authors concluded that erionite caused chromosome changes similar to those caused by asbestos-like dusts and, like asbestos, did not cause mutations in these human cells. They noted that excluding cells covered by fiber clumps may have contributed to the lack of a clear dose-response.

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 culture experiment comparing the genetic effects of erionite, crocidolite asbestos and quartz
• Who was studied: Synchronized Chinese hamster ovary (CHO) fibroblasts, used for the chromosome tests, and the human lymphoblastoid cell line TK6, used for the mutation tests at two genetic loci
• Exposure: Erionite fibres from Rome, Oregon (USA), used because enriched Karain erionite was unavailable; UICC standard crocidolite asbestos; Min-U-Sil quartz as a non-fibrous comparison. Ultraviolet light (CHO cells) and 1.5 Gy X-rays (lymphoblasts) were positive controls. Lymphoblasts were treated for 24 h.
• Main results:
  • Erionite significantly raised sister chromatid exchanges in CHO cells in all four experiments, by 17% to 26% above baseline
  • Crocidolite significantly raised sister chromatid exchanges at only one dose in one experiment, with no consistent dose pattern
  • Min-U-Sil quartz did not raise sister chromatid exchanges in CHO cells
  • The ultraviolet light positive control raised sister chromatid exchanges to about three times baseline
  • Both crocidolite and erionite caused low, similar levels of chromosomal aberrations in CHO cells; quartz did not raise aberrations above background
  • Both crocidolite and erionite increased the percentage of tetraploid CHO cells (cells with doubled chromosome sets); crocidolite may have been slightly more potent; quartz did not noticeably affect ploidy
  • Neither erionite nor crocidolite induced mutations at either genetic locus in the human lymphoblastoid cells
  • In the human lymphoblastoid cells, crocidolite was slightly toxic at high doses, while erionite did not affect cell survival at any dose tested
  • X-rays (1.5 Gy), the positive control, killed lymphoblasts and induced mutations at both loci
• The authors' conclusion: The authors concluded that erionite fibres caused cytogenetic changes similar to those caused by asbestiform mineral dusts and, like asbestos minerals, did not induce mutations in human lymphoblastoid cells.
• Limitations the authors state:
  • At higher doses, cells covered by fibre clusters were excluded from analysis, which may have contributed to the apparent lack of a dose-response relationship
  • Erionite from Karain, Turkey was not available in fibre-enriched form, so erionite from Oregon was used instead
  • Some fibres were not removed after the 24 h treatment, so the lymphoblasts were exposed to low concentrations for longer than intended
  • The threshold dose of erionite needed to induce sister chromatid exchanges appeared to vary between experiments

Topics

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

Medical terms in this study, explained in our Lexicon: erionite, Crocidolite, Endemic, Peritoneal Mesothelioma, Zeolite, Fibroblast, Asbestiform.

Related studies

• In vitro genotoxic activities of fibrous erionite — A. Poole, R.C. Brown, et al. (1983)
• Metaphase and anaphase analysis of V79 cells exposed to erionite, UICC chrysotile and UICC crocidolite — L.D. Palekar, J.F. Eyre, et al. (1987)
• Sister-chromatid exchange and cell kinetics in CHO-K1 cells, human fibroblasts and lymphoblastoid cells exposed in vitro to asbestos and glass fibre — G. Casey (1983)
• CT findings in malignant pleural mesothelioma related to nonoccupational exposure to asbestos and fibrous zeolite (erionite) — C. Erzen, M. Eryilmaz, et al. (1991)
• Biodurability and release of metals during the dissolution of chrysotile, crocidolite and fibrous erionite — A.F. Gualtieri, G. Lusvardi, et al. (2019)
• Cytotoxic and genotoxic effects of calcium silicates on human lymphocytes in vitro — M. Aslam, N. Fatima, et al. (1993)

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