Demonstration of nitric oxide on asbestos and silicon carbide fibers with a new ultraviolet spectrophotometric assay

Our plain-English summary of Demonstration of nitric oxide on asbestos and silicon carbide fibers with a new ultraviolet spectrophotometric assay, by P. Leanderson, V. Lagesson, C. Tagesson (Environmental Health Perspectives, 1997).

The study

• Authors: P. Leanderson, V. Lagesson, C. Tagesson
• Journal: Environmental Health Perspectives
• Published: 1997;105 Suppl 5(Suppl 5):1037-40
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Nitric oxide (NO) has a number of important functions in biological systems and may play a role in the toxicity of mineral fibers. We investigated whether NO might be present on the surface of mineral fibers and if crocidolite could adsorb NO from NO gas or cigarette smoke. NO was determined with a new gas chromatography-ultraviolet spectrophotometric technique after thermal desorption from the fiber surface and injection in a gas flow cell. NO was found in different amounts on chrysotile B, crocidolite, amosite, and silicon carbide whiskers. There was a strong correlation between the amount of NO and the specific surface area of these fibers (r = 0.98). NO could not be demonstrated on rockwool fibers [man-made vitreous fiber(s) (MMVF)21 and MMVF22] or silicon nitride whiskers. NO on crocidolite, amosite, and silicon carbide whiskers was readily desorbed from the fibers at increased temperature, while NO on chrysotile B seemed to be more firmly adsorbed to the fiber and required a longer period of time to be desorbed. The amount of NO bound to crocidolite increased from 34 micrograms/g fiber to 85 and 474 micrograms/g after exposing the fibers to cigarette smoke and NO gas, respectively. These findings indicate that a) NO adsorbs to fiber surfaces, b) some fibers adsorb more NO than others, c) some fibers adsorb NO more strongly than others, and d) the amounts of NO on fibers may be increased after exposure of the fiber to cigarette smoke or other sources of NO. The biological significance of NO on mineral fibers remains to be investigated.

In plain English

This laboratory study tested whether nitric oxide (NO), a gas with many functions in biological systems, is present on the surface of mineral fibers. The authors heated fiber samples to 190°C to release surface compounds and measured NO with a new gas chromatography and ultraviolet light technique. They examined three standard asbestos samples (crocidolite, chrysotile B and amosite), silicon carbide whiskers, silicon nitride whiskers and two rockwool fibers (MMVF21 and MMVF22). NO was found on chrysotile B (103 micrograms per gram of fiber), crocidolite (34), silicon carbide whiskers (25) and amosite (15). It was not detected on the silicon nitride whiskers or the rockwool fibers. Among the four fibers that carried NO, the amount was strongly correlated with the fibers' surface area (r=0.98). NO came off chrysotile B more slowly than off the other fibers. After exposure to cigarette smoke, crocidolite carried 85 micrograms per gram, and after exposure to NO gas it carried 474. The authors could not explain where the NO on the untreated fibers came from. They stated that its biological significance remains to be investigated.

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 (chemical analysis) experiment on fiber samples; no people or animals were studied
• Who was studied: Fiber samples: UICC standard crocidolite, chrysotile B and amosite; silicon carbide whiskers (Tateho Chemical, Japan); silicon nitride whiskers (UBE Industries, Japan); two rockwool fibers (MMVF21 and MMVF22)
• Exposure: NO already present on the fiber surfaces was measured. In addition, 10 to 30 mg of crocidolite was exposed to either 40 ml of 10% NO gas in nitrogen or 40 ml of smoke from a commercial filter cigarette, shaken for 30 seconds, then analyzed.
• Main results:
  • NO was found on chrysotile B, crocidolite, amosite and silicon carbide whiskers. Chrysotile B had the highest amount. Table 1 values in micrograms per gram of fiber: crocidolite 34, chrysotile B 103, amosite 15, silicon carbide whiskers 25.
  • NO was not detected on silicon nitride whiskers or on the two rockwool samples (MMVF21 and MMVF22).
  • Across the four fibers that carried NO, the amount of NO was strongly correlated with specific surface area (r = 0.98). The surface areas were taken from the literature for the asbestos samples and from the manufacturer for the whiskers.
  • NO was released readily from crocidolite, amosite and silicon carbide on heating. NO on chrysotile B appeared more firmly attached and needed more time at 190°C to be released.
  • Cigarette smoke treatment raised NO on crocidolite from 34 to 85 micrograms per gram of fiber.
  • Treatment with 10% NO gas raised NO on crocidolite from 34 to 474 micrograms per gram of fiber, which the authors describe as a more than 10-fold increase.
• The authors' conclusion: The authors concluded that NO adsorbs to fiber surfaces, that some fibers adsorb more NO than others, that some adsorb it more strongly than others, and that the amount of NO on fibers may increase after exposure to cigarette smoke or other sources of NO. They stated that the biological significance remains to be investigated.
• Limitations the authors state:
  • The authors could not explain the source of the NO found on the untreated fibers. The asbestos samples were UICC standards prepared about 30 years earlier.
  • The authors stated it remains to be clarified whether the heat-release step recovers all of the NO.
  • The biological effects of NO on fiber surfaces were not studied. The authors said it is unclear whether NO would increase or decrease fiber toxicity.

Topics

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

Medical terms in this study, explained in our Lexicon: Mineral Fiber, Crocidolite, Chrysotile, Amosite, Vitreous.

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