Hydroxyl radical production in the presence of fibres by a Fenton-type reaction

Our plain-English summary of Hydroxyl radical production in the presence of fibres by a Fenton-type reaction, by M. Gulumian, J.A. van Wyk (Chemico-biological Interactions, 1987).

The study

• Authors: M. Gulumian, J.A. van Wyk
• Journal: Chemico-biological Interactions
• Published: 1987;62(1):89-97
• Cited by: 53 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Glass fibres are considered to be inert and therefore thought to present no real hazard to the health of people who inhale them. Results in the present study however indicate that these fibres are able to produce hydroxyl radicals in the presence of hydrogen peroxide by a Fenton-type reaction. Since hydroxyl radical is implicated in lipid peroxidation, single-strand DNA breaks and carcinogenesis, care should be exercised when dealing with glass fibres.

In plain English

This was a laboratory chemistry experiment, not a study of people or animals. The authors, in Johannesburg, South Africa, mixed glass fibres (sample C104) or UICC reference crocidolite asbestos with hydrogen peroxide. They used electron spin resonance to detect hydroxyl radicals, a highly reactive form of oxygen. Glass fibres generated hydroxyl radicals when hydrogen peroxide was present. Without hydrogen peroxide no signal appeared. The amount detected was related to the amounts of hydrogen peroxide and glass fibres. Glass fibres produced almost three times more hydroxyl radicals than the same concentration of crocidolite. This was so even though the glass fibres contained less than 0.05% iron, while iron is a major constituent of crocidolite. Two substances that bind metal ions sharply reduced the signal: from 8.3 cm with glass fibres alone to 0.5 cm with DTPA and 0.0 cm with desferrioxamine. The authors took this to mean that ions in the fibres drive the reaction. Milled glass fibres gave a stronger signal, as did milled crocidolite. The authors called the strong glass-fibre signal surprising. They concluded that hydroxyl radical production might play a role in glass fibre toxicity and advised more caution with the fibre.

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 (test-tube, cell-free) chemistry experiment using electron spin resonance (ESR) spin trapping
• Who was studied: No people or animals. Fibre samples were tested: glass fibres (sample reference C104, Johns-Manville of Canada) and UICC reference crocidolite. The work was done by researchers in Johannesburg, South Africa.
• Exposure: Unless otherwise specified, the reaction mixture contained 0.1 ml of 35 mM hydrogen peroxide, 0.1 ml of 2 mg/ml fibre and 50 microlitres of the purified spin trap DMPO, made up to 0.5 ml with phosphate buffer. Coarse and milled forms of both fibre types were tested.
• Main results:
  • Glass fibres generated hydroxyl radicals in the presence of hydrogen peroxide.
  • When hydrogen peroxide was left out, the signal was not produced.
  • The amount of hydroxyl radical trapped was related to the concentrations of both hydrogen peroxide and glass fibres in the reaction mixture.
  • Glass fibres produced almost three times more hydroxyl radicals than the same concentration of crocidolite fibres.
  • Adding catalase, the metal-binding agents DTPA and desferrioxamine (DFO), or mannitol substantially decreased the signal produced by glass fibres. In Table I, the peak-to-peak height was 8.3 cm with glass fibres alone. It was 1.0 cm with mannitol, 0.5 cm with DTPA, 0.0 cm with DFO at both concentrations tested, and 0.4 cm with catalase.
  • The authors wrote that DTPA and DFO abolished the signal and interpreted this as showing that ions in the glass fibre structure are essential catalysts for the reaction. Table I shows a residual signal of 0.5 cm with DTPA.
  • Iron is a major constituent of crocidolite, while the iron content of the glass fibres was less than 0.05%.
  • Milled glass fibre (80 micrometre mean length) gave a stronger signal, and the same was true for milled crocidolite.
• The authors' conclusion: The authors concluded that hydroxyl radical production might play a role in determining the toxicity of glass fibres, and that more caution should be exercised in dealing with this fibre.
• Limitations the authors state:
  • Leaving out the fibres still gave a small background signal, despite precautions to remove trace ions from the buffer and glassware. These results were not shown.
  • The stored spin trap (DMPO) gave a weaker signal than on its first day of preparation.
  • The authors could not yet explain why the low-iron glass fibres gave such a high signal and said this was under further investigation.

Topics

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

Medical terms in this study, explained in our Lexicon: Hydroxyl Radical, Carcinogenesis.

Related studies

• Asbestos catalyzes hydroxyl and superoxide radical generation from hydrogen peroxide — S.A. Weitzman, P. Graceffa (1984)
• Identifying the reactive sites of hydrogen peroxide decomposition and hydroxyl radical formation on chrysotile asbestos surfaces — M. Walter, W.D.C. Schenkeveld, et al. (2020)
• Dusts causing pneumoconiosis generate .OH and produce hemolysis by acting as Fenton catalysts — T.P. Kennedy, R. Dodson, et al. (1989)
• Fenton reaction induced cancer in wild type rats recapitulates genomic alterations observed in human cancer — S. Akatsuka, Y. Yamashita, et al. (2012)
• Fiber-induced hydroxyl radical formation: correlation with mesothelioma induction in rats and humans — K.R. Maples, N.F. Johnson (1992)
• A study of the synergistic interaction of asbestos fibers with cigarette tar extracts for the generation of hydroxyl radicals in aqueous buffer solution — A. Valavanidis, H. Balomenou, et al. (1996)

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