Mount St. Helens' volcanic ash: hemolytic activity

Our plain-English summary of Mount St. Helens' volcanic ash: hemolytic activity, by V. Vallyathan, M.S. Mentnech, L.E. Stettler, et al (Environmental Research, 1983).

The study

• Authors: V. Vallyathan, M.S. Mentnech, L.E. Stettler, D.D. Dollberg, F.H. Green
• Journal: Environmental Research
• Published: 1983;30(2):349-60
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Volcanic ash samples from four Mount St. Helens' volcanic eruptions were subjected to mineralogical, analytical, and hemolytic studies in order to evaluate their potential for cytotoxicity and fibrogenicity. Plagioclase minerals constituted the major component of the ash with free crystalline silica concentrations ranging from 1.5 to 7.2%. The in vitro hemolytic activity of the volcanic ash was compared to similar concentrations of cytotoxic and inert minerals. The ash was markedly hemolytic, exhibiting an activity similar to chrysotile asbestos, a known fibrogenic agent. The hemolysis of the different ash samples varied with particle size but not with crystalline silica concentration. The results of these studies taken in conjunction with the results of our animal studies indicate a fibrogenic potential of volcanic ash in heavily exposed humans.

In plain English

This was a laboratory study by researchers at the National Institute of Occupational Safety and Health of volcanic ash from the Mount St. Helens eruptions in Washington state. Five ash samples, collected at locations representing four eruptions, were analyzed for minerals and particle size. They were also tested for how strongly they broke open sheep red blood cells (hemolysis), a quick test of how toxic a dust is to cells. The ash was compared with nine other mineral dusts, including chrysotile, amosite and crocidolite asbestos. The ash was mostly plagioclase minerals with 1.5 to 7.2% crystalline silica, and no asbestos-like minerals were found. At the standard concentration of 12.5 mg/ml, one ash sample caused 64% hemolysis, compared with 94.3% for crystalline silica, 67.9% for chrysotile and 57.9% for talc. At that concentration, the Centralia and Chewalah samples caused about 50% less hemolysis than the other ash samples. Silica content did not significantly change hemolysis, but particle size did. The authors noted that this test can give false negative results for some dusts, such as crocidolite. Combining these results with their separate animal studies, the authors concluded that the ash has a potential to cause lung scarring (fibrosis) in heavily exposed people.

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 (in vitro) study: mineral and particle-size analysis of volcanic ash, plus a hemolysis test on sheep red blood cells, compared with other mineral dusts
• Who was studied: Five bulk, settled, dry volcanic ash samples from Mount St. Helens eruptions. They were collected at Spokane and Moses Lake (first eruption), Centralia (second), Gales Creek (third) and Chewalah (fourth). No people were studied.
• Exposure: Volcanic ash, tested at a standard concentration of 12.5 mg/ml and at varying concentrations. It was compared with nine mineral dusts chosen for their known biological properties: crystalline silica, kaolin, chrysotile, talc, coal, bentonite, amosite, gypsum and crocidolite.
• Main results:
  • The ash samples were mainly plagioclase minerals. Total free crystalline silica varied between samples, from 1.5% (Moses Lake) to 7.2% (Spokane) in Table 1.
  • No asbestiform minerals were identified in any of the ash samples.
  • Counted by number of particles, 99% of ash particles were in the respirable size range (less than 10 micrometers).
  • At 12.5 mg/ml, the Spokane ash sample caused 64% hemolysis, compared with 94.3% for crystalline silica.
  • The authors reported that the ash's hemolysis level corresponded well with chrysotile (67.9%) and talc (57.9%).
  • All ash samples caused more hemolysis at higher concentrations.
  • At the standard concentration of 12.5 mg/ml, the Centralia (second eruption) and Chewalah (fourth eruption) samples caused about 50% less hemolysis than the other ash samples.
  • Differences in crystalline silica content among the ash samples did not significantly change hemolysis.
  • Particle size (mass median diameter) significantly influenced hemolysis. Smaller particles, with more surface area, caused the most hemolysis.
• The authors' conclusion: The authors concluded that the ash samples showed hemolytic activity similar to chrysotile asbestos. This activity depended more on particle size than on free silica content. Taken together with their separate animal studies, the authors concluded the results indicate a fibrogenic potential of volcanic ash in heavily exposed humans (the abstract's wording; the closing section says 'exposed humans' and calls for minimizing exposure in high risk occupational groups).
• Limitations the authors state:
  • The calculated particle-size values (mass median and aerodynamic diameters) are rather crude approximations.
  • Some samples were not very uniform and contained a significant weight percentage of non-respirable particles.
  • Only the Moses Lake sample was size-fractionated (to less than 5 micrometers). The other samples were tested unfractionated because there was not enough material.
  • Hemolysis is affected by factors other than a mineral's toxicity.
  • The hemolysis test has notable exceptions that give false negative results, such as crocidolite asbestos.

Topics

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

Related studies

• The hemolytic activity of chrysotile asbestos fibers: a freeze-fracture study — J.P. Pelé, J. Dunnigan, et al. (1983)
• Surface charge and hemolytic activity of asbestos — W.G. Light, E.T. Wei (1977)
• Polymers as selective antagonists of hemolytic asbestos fibers — R.J. Schnitzer, G. Bunescu (1970)
• A comparative study on the hemolytic action of short asbestos fibers on human, rat, and sheep erythrocytes — J.P. Pelé, R. Calvert (1983)
• Haemolytic activity of asbestos and other mineral dusts — G. Macnab, J.S. Harington (1967)
• Cell toxicity, hemolytic action and clastogenic activity of asbestos and its substitutes — K. Koshi, N. Kohyama, et al. (1991)

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