Asbestos catalyzes hydroxyl and superoxide radical generation from hydrogen peroxide

Our plain-English summary of Asbestos catalyzes hydroxyl and superoxide radical generation from hydrogen peroxide, by S.A. Weitzman, P. Graceffa (Archives of Biochemistry and Biophysics, 1984).

The study

• Authors: S.A. Weitzman, P. Graceffa
• Journal: Archives of Biochemistry and Biophysics
• Published: 1984;228(1):373-6
• Cited by: 254 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To understand chemical characteristics of the asbestos minerals which might contribute to tissue damage, the catalytic properties of three different varieties were studied. Using spin trapping techniques it was determined that crocidolite, chrysotile, and amosite asbestos were all able to catalyze the generation of toxic hydroxyl radicals from a normal byproduct of tissue metabolism, hydrogen peroxide. The iron chelator desferroxamine inhibits this reaction, indicating a major role for iron in the catalytic process, and suggesting a possible mechanism by which asbestos toxicity might be reduced.

In plain English

This short laboratory report tested whether asbestos fibers can generate reactive oxygen radicals from hydrogen peroxide, a normal byproduct of body chemistry. The authors suspended standard reference samples of crocidolite, Canadian chrysotile and amosite in water and mixed them with hydrogen peroxide and a chemical 'trap' that lets short-lived radicals be detected by electron spin resonance spectroscopy. No people, animals or cells were studied. All three fiber types produced the signal of hydroxyl radical, a highly reactive molecule. Crocidolite and amosite also showed signals the authors identified as superoxide radical. Washing the fibers with water did not significantly change the hydroxyl signal. The iron-binding chemical desferroxamine markedly suppressed it for all three types. Another binding chemical, EDTA, increased the signal with crocidolite but reduced it with chrysotile and amosite. Acid-washing crocidolite, meant to remove metal contaminants, gave a 100% increase in the signal. The authors took this to mean the activity was built into the asbestos structure. The authors concluded that much of this activity, and some of asbestos's toxicity in the body, may be related to iron content.

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) chemistry experiment, published as a short communication, using electron spin resonance spectroscopy with a spin trapping agent to detect radicals
• Who was studied: No human or animal subjects. Three types of asbestos fiber were studied: crocidolite, Canadian chrysotile and amosite, all U.I.C.C. Reference Standard samples
• Exposure: Asbestos fibers suspended in deionized distilled water at 1.0 mg/ml, incubated with hydrogen peroxide. Some experiments added, or pre-washed the fibers with, the chelators EDTA or desferroxamine.
• Main results:
  • The hydroxyl radical signal was observed when each of the three asbestos types (crocidolite, chrysotile, amosite) was incubated with hydrogen peroxide
  • Washing the asbestos with water did not significantly affect the hydroxyl radical signal
  • Desferroxamine markedly suppressed hydroxyl radical generation by all three asbestos types, whether present during incubation or used to wash the fibers beforehand
  • EDTA markedly increased hydroxyl radical production with crocidolite, but inhibited it with chrysotile and amosite
  • Additional spectral lines were seen with crocidolite and amosite. The authors identified them as superoxide radical because they disappeared when the enzyme superoxide dismutase was added.
  • Adding superoxide dismutase also produced higher hydroxyl radical peaks than comparable incubations without it. The authors stated they were uncertain of the cause.
  • Crocidolite that had been acid-washed to remove metal contaminants gave a 100% increase in the hydroxyl radical adduct signal compared with native crocidolite
  • The authors interpreted the acid-wash result as showing that the catalytic properties are part of the asbestos structure, not due to metal contamination
• The authors' conclusion: The authors concluded that much of the catalytic activity they observed, and some of the toxicity of asbestos in the body, may be related to iron content

Topics

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

Medical terms in this study, explained in our Lexicon: Superoxide, Asbestos, Crocidolite, Chrysotile, Amosite, Hydroxyl Radical.

Related studies

• Generation of hydroxyl radical by crocidolite asbestos is proportional to surface [Fe3+] — A.J. Ghio, J. Zhang, et al. (1992)
• 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)
• Hydroxyl radical production in the presence of fibres by a Fenton-type reaction — M. Gulumian, J.A. van Wyk (1987)
• Role of oxidants in DNA damage. Hydroxyl radical mediates the synergistic DNA damaging effects of asbestos and cigarette smoke — J.H. Jackson, I.U. Schraufstatter, et al. (1987)
• Fiber-induced hydroxyl radical formation: correlation with mesothelioma induction in rats and humans — K.R. Maples, N.F. Johnson (1992)
• The release of iron from different asbestos structures by hydrogen peroxide with concomitant O2 generation — A.J. Ghio, D.E. Taylor, et al. (1998)

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