Solubility of chrysotile asbestos and basalt fibers in relation to their fibrogenic and carcinogenic action

Our plain-English summary of Solubility of chrysotile asbestos and basalt fibers in relation to their fibrogenic and carcinogenic action, by F.M. Kogan, O.V. Nikitina (Environmental Health Perspectives, 1994).

The study

• Authors: F.M. Kogan, O.V. Nikitina
• Journal: Environmental Health Perspectives
• Published: 1994;102 Suppl 5(Suppl 5):205-6
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Fiber length and persistence are thought to be determinants for the development of toxic, fibrogenic, and carcinogenic effects of fibrous dusts. When the solubilities of chrysotile asbestos (CA) and basalt fibers (BF) were compared by measuring the loss of silica and magnesium in Leineweber's solution, CA was shown to be the more soluble. In a 6-month inhalation experiment, chrysotile at a mean concentration of 25 mg/m3 had a higher clearance rate than other comparable dusts. In acute toxicity studies, chrysotile and basalt fibers were administered intraperitoneally. At a dose of 1.7 g/kg body weight of CA, one third of the animals died. A dose of 2.7 g/kg body weight killed all the animals. With BF, even at a dose of 10 g/kg body weight all the animals survived. When the two fibers were administered over a 6-month period, either intratracheally or by inhalation, fibrotic lesions were more common in the group that received CA. Intraperitoneal administration of CA led to three times as many deaths from peritoneal mesothelioma as administration of BF. It appears, therefore, that in spite of its higher solubility and lower persistence, CA was the more toxic, fibrogenic and carcinogenic fiber, which gives rise to the hypothesis that the surface chemistry of the fibers is the determinant for biological activity.

In plain English

This short paper from a 1992 workshop reported laboratory tests and animal experiments from a research center in Ekaterinburg, Russia. It compared chrysotile asbestos from the Central Urals with basalt fibers, a possible substitute for chrysotile. In a salt solution at 37°C, more silica and magnesium dissolved from chrysotile over 15 days than from two basalt fiber types. Six months after 55 mg was placed into rats' windpipes, less chrysotile than basalt fiber remained in the lungs. After inhalation, less chrysotile than a granular serpentinite dust remained in rats and guinea pigs. Injected into rats' abdomens, basalt fiber at 10 g/kg body weight caused no acute-toxicity deaths, but 12 to 14% developed peritoneal mesothelioma. Chrysotile killed 33% of animals at 1.7 g/kg and 100% at 6.0 g/kg, and 45% developed peritoneal mesothelioma. Chrysotile caused significantly more lung fibrosis. The authors concluded that factors besides solubility and persistence, including fiber number per unit mass and surface properties, must influence fiber effects. Animal numbers were not reported; where abstract figures differ from the main text, this summary follows the text.

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 solubility tests of fibers in a simulated body fluid (Leineweber's solution), plus animal experiments (lung retention, acute toxicity, fibrosis and mesothelioma after intraperitoneal injection). Short workshop paper.
• Who was studied: Rats (intratracheal instillation, inhalation, intraperitoneal injection) and guinea pigs (inhalation). Animal numbers are not reported. The work came from the Medical Research Center for Health Protection of Industrial Workers, Ekaterinburg, Russia, and was presented in September 1992.
• Exposure: Chrysotile asbestos from the Central Urals deposit (11.1% fibrous particles, 76% of them respirable). It was compared with basalt fiber in three nominal diameters (micro, ultra and superthin) and, in the inhalation retention tests, with a granular serpentinite dust. Doses were 55 mg per rat intratracheally, 25 mg/m3 or 113.8 mg/m3 by inhalation, and 1.7 to 10 g/kg body weight intraperitoneally.
• Main results:
  • Solubility: both ultrathin and superthin basalt fibers were less soluble than chrysotile. After 15 days, dissolved SiO2 was 13.0 mg% for superthin basalt, 14.0 for ultrathin basalt and 29.1 for chrysotile. Dissolved Mg was 0.06, 0.10 and 5.0 mg% respectively.
  • Rats given 55 mg by intratracheal instillation: 6 months later, the lungs held 8.4 mg chrysotile per 100 mg dry lung, compared with 11.0 to 11.4 mg basalt fiber. At 3 months the figures were 10.7 and 11.1 to 15.5 mg.
  • Inhalation in rats, measured 3 months after exposure: the mean weight retained was 3.34 mg for chrysotile and 20.5 mg for serpentinite, for an equal weight of dry lung.
  • Inhalation in guinea pigs, measured 9 months after exposure: the mean weight retained was 9.9 mg for chrysotile and 36.7 mg for serpentinite.
  • Intraperitoneal basalt fiber at 10 g/kg body weight in rats caused no deaths from acute toxicity, but 12 to 14% of the rats developed peritoneal mesotheliomas.
  • Intraperitoneal chrysotile in rats killed 33% of animals at 1.7 g/kg body weight, 50% at 2.2 g/kg and 100% at 6.0 g/kg.
  • 45% of chrysotile-treated test animals developed peritoneal mesotheliomas.
  • In rats given 55 mg per rat intratracheally or 25 mg/m3 by inhalation, chrysotile caused significantly more fibrotic lesions than basalt fiber. These included diffuse sclerotic changes around the bronchioles, small vessels and alveolar walls.
• The authors' conclusion: The authors assumed that chrysotile's higher fibrogenic activity was due to its greater number of long, thin fibers and larger surface area. They concluded that, although chrysotile appeared less persistent, factors other than solubility and persistence must influence a fiber's biological activity: the number of fibers per unit mass, the fiber's surface properties, and its interaction with biological structures.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Fibrogenic, Carcinogenic, Fiber Length, Peritoneal Mesothelioma.

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