An assessment of the fibrogenic potential of two refractory fibres by intraperitoneal injection in rats

Our plain-English summary of An assessment of the fibrogenic potential of two refractory fibres by intraperitoneal injection in rats, by G.H. Pigott, J. Ishmael (Toxicology Letters, 1981).

The study

• Authors: G.H. Pigott, J. Ishmael
• Journal: Toxicology Letters
• Published: 1981;8(3):153-63
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Two commercially available grades of the refractory fibre SAFFIL were administered to rats by intraperitoneal injection and the tissue reaction was compared. Although the fibres differed considerably in surface properties and porosity the tissue reactions were identical and consisted of a mild chronic inflammatory response with a small amount of collagen present. The reaction was quite distinct from the marked fibrosis induced by chrysotile asbestos. As the reaction to all fibres tested had stabilised after 6 months, a longer observation period is unnecessary.

In plain English

This animal experiment compared tissue reactions in rats to two commercial grades of SAFFIL, an alumina fibre, and to chrysotile asbestos. Groups of 24 Wistar rats (12 of each sex) were each injected into the abdominal cavity with 20 mg of SAFFIL Type A, SAFFIL Type B, or UICC Rhodesian chrysotile. Control rats received saline. Rats were killed and examined at intervals up to 12 months. The two SAFFIL grades differed considerably in surface properties and porosity. Both produced fibre nodules with a mild chronic inflammatory reaction and small amounts of collagen, with no evidence of progressive fibrosis. Chrysotile produced hard fibrous nodules with necrotic (dead) centres and adhesions in the abdomen. No mesothelioma was seen. Three other tumours occurred in the asbestos group, which the authors considered of somewhat doubtful significance. The authors concluded that the surface differences did not affect the peritoneal reaction. They also concluded that a 6-month observation period was adequate when the test is used to assess fibrogenic potential. They noted that small groups and the short timescale made this a most insensitive test for carcinogenesis.

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: Animal experiment: intraperitoneal injection in rats comparing two commercial grades of SAFFIL alumina fibre with chrysotile asbestos (as a fibrogenic control) and saline controls
• Who was studied: Specific pathogen-free albino Wistar rats (Alderley Park strain) of both sexes, 140-160 g on receipt. There were four groups of 24 rats (12 of each sex): saline control, chrysotile asbestos, SAFFIL Type A and SAFFIL Type B. Rats were killed at 3 months (control and SAFFIL Type A groups only), 6 months and 12 months.
• Exposure: A single intraperitoneal injection of 20 mg (0.2 ml of a 10% suspension) of SAFFIL Type A, SAFFIL Type B, or UICC standard reference Rhodesian chrysotile asbestos. Control animals received 0.2 ml saline.
• Main results:
  • The two SAFFIL grades differed considerably in surface properties and porosity, but the tissue reactions were identical: a mild chronic inflammatory response with a small amount of collagen.
  • In SAFFIL Type A rats, the nodules looked similar at all time points, with no evidence of progressive fibrosis.
  • In SAFFIL Type B rats, the reaction under the microscope was indistinguishable from that seen with SAFFIL Type A.
  • Chrysotile-injected rats had nodules made of dense fibrous tissue with necrotic centres.
  • Chrysotile-injected rats also had yellow nodular lesions with adhesions between the abdominal lining and the small and large intestines, at both 6 and 12 months.
  • In SAFFIL Type A rats, fibres were found in lymph nodes, with no apparent reaction to them.
  • No mesothelioma was observed in this experiment.
  • Three tumours (a pituitary adenoma, a subcutaneous fibroma and an islet cell adenoma of the pancreas) were seen at the 12-month kill, all in the asbestos group.
  • The authors considered the three tumours in the asbestos group to be of somewhat doubtful significance.
  • There was no significant difference in body weight between any treated group and the controls.
  • The authors judged that a 6-month observation period is adequate when the test is used to assess fibrogenic potential.
• The authors' conclusion: The authors concluded that the reaction to both SAFFIL fibres was identical at 6 and 12 months, and that the fibres' differing surface properties were not significant in determining the peritoneal reaction. They also concluded that a 6-month observation period is adequate when the test is used to assess fibrogenic potential.
• Limitations the authors state:
  • Small group sizes and the relatively short timescale made the experiment a most insensitive test for carcinogenesis.
  • The length distribution of fibres could not be measured at the end of the experiment.
  • A few animals showed no response, and responses were not graded. The authors had not determined why the asbestos reaction was 'all or nothing'.

Topics

Medical terms in this study, explained in our Lexicon: Fibrogenic, Collagen, Fibrosis, Chrysotile.

Related studies

• The effects of intrapleural injections of alumina and aluminosilicate (ceramic) fibres — G.H. Pigott, J. Ishmael (1992)
• Acute and chronic effects of intraperitoneal injection of two types of asbestos in rats with a study of the histopathogenesis and ultrastructure of resulting mesotheliomas — M.L. Shin, H.I. Firminger (1973)
• An epidemiological study of the respiratory health of workers in the European refractory ceramic fibre industry — H.A. Cowie, P. Wild, et al. (2001)
• An assessment of the fibrogenic potential of very short 4T30 chrysotile by intratracheal instillation in rats — I. Lemaire, D. Nadeau, et al. (1985)
• Additional atypical malignant mesothelioma after intraperitoneal injection of mineral fibres in rats — K. Kamino, H. Ernst, et al. (1993)
• P53 mutations in tumours induced by intraperitoneal injection of crocidolite asbestos and benzo[a]pyrene in rats — K. Unfried, N. Kociok, et al. (1997)

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