Asbestos hemolysis

Our plain-English summary of Asbestos hemolysis, by R.J. Schnitzer, F.L. Pundsack (Environmental Research, 1970).

The study

• Authors: R.J. Schnitzer, F.L. Pundsack
• Journal: Environmental Research
• Published: 1970;3(1):1-13
• Cited by: 58 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001408).

Abstract

Chrysotile fibers exert a marked hemolytic activity on suspensions of washed sheep erythrocytes, but amphibole asbestiform minerals such as crocidolite, amosite, tremolite, and anthophyllite possess only negligible hemolytic properties. The minimal hemolytic concentration of chrysotile asbestos is dependent on the openness of the fibers as characterized by the air permeability surface area and decreases with increasing surface area. This fact was also observed in the evaluation of hemolysis of fibrous, nonasbestiform minerals, e.g., sepiolite and nemalite. Chrysotile hemolysis can be inhibited by disodium ethylenediaminetetraacetic acid (EDTA) and by certain acidic polymers particularly by polystyrene sulfonates, carboxymethylcellulose ether sodium salt (CMC), and the pyran-copolymer NSC 46015. These substances are not effective as inhibitors of silica (quartz) hemolysis, whereas polyvinylpyridine-N-oxide (PVPNO), a very potent antagonist of silica hemolysis, interferes with chrysotile only at high concentrations. The hemolytic action of chrysotile can be markedly reduced by repeated treatment with red blood cells. The mechanism of asbestos hemolysis cannot yet be satisfactorily interpreted. There is a marked correlation of hemolytic potency with the surface area and the degree of opening of the fibers which may be influenced by the action of the antagonistic polymers. The role of the magnesium hydroxide surface characteristic for chrysotile is not yet elucidated, because magnesium hydroxide is not hemolytic, although nemalite, a natural fibrous magnesium hydroxide, and a lightly burned magnesium oxide are active hemolytic agents.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

The authors tested 64 materials for their ability to burst (hemolyze) washed sheep red blood cells. These included chrysotile from several mines, the amphiboles crocidolite, amosite, anthophyllite and tremolite, other fibrous minerals, and magnesium compounds. At the screening dose of 12.5 mg/ml, all milled chrysotile samples were hemolytic, hand-cut crude chrysotile was not, and no amphibole was substantially active, although the authors noted amphiboles may hemolyze under other conditions. In one comparison of crude and milled Jeffrey Mine samples, air-jet milling raised potency more than 40-fold; potency rose with fiber surface area. EDTA and several acidic polymers, particularly carboxymethylcellulose and a pyran-copolymer, inhibited chrysotile hemolysis. Polyvinylpyridine-N-oxide, a strong inhibitor of quartz hemolysis, was substantially less effective against chrysotile. Washing with saline or EDTA did not remove chrysotile's activity; repeated exposure to red cells reduced or eliminated it. The authors concluded that chrysotile's hemolytic activity is related to the fibers' surface area or degree of opening, and that the mechanism could not yet be satisfactorily explained. They noted that no relationship between such hemolysis findings and the minerals' disease-causing potential was known.

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: In vitro laboratory experiment measuring hemolysis (bursting) of washed sheep red blood cells by mineral samples
• Who was studied: 64 materials were tested on 2% suspensions of three-times-washed sheep red blood cells.

Chrysotile samples came from:

• the Jeffrey Mine (Quebec)
• Coalinga (California)
• the Advocate Mine (Newfoundland)
• the Reeves Mine (Ontario)
• Arizona (soft and harsh fibers)
• the Carey Mine (Quebec)
• the Cassiar Mine (British Columbia)
• Munro (Ontario)
• UICC chrysotile A and B

Amphiboles were:

• crocidolite from Africa, plus a UICC sample
• amosite from Africa, plus a UICC sample
• anthophyllite, including a UICC sample
• tremolite

Also tested were non-asbestiform fibrous materials (sepiolite, nemalite, micro-quartz, fibrous talc, palygorskite), magnesium hydroxide, burned magnesium oxide, and miscellaneous products. No dates are given.

• Exposure: Materials were added to red cell suspensions and incubated at 37°C for 2 hours. Routine tests used 12.5 mg/ml; titrations used graded lower amounts. Fibers were tested in three forms: hand-cut (crude), hammer-milled, or air-jet-milled.

Inhibitors tested were EDTA, other chelating agents, and water-soluble polymers:

• methylcellulose
• carboxymethylcellulose
• polystyrene sulfonates
• a pyran-copolymer
• polyvinylpyridine-N-oxide

Surface treatments of the fibers were also tested.

• Main results:
  • In qualitative screening at the standard dose of 12.5 mg/ml, all hammer-milled and air-jet-milled chrysotile samples were hemolytic. None of the hand-cut crude chrysotile samples was active.
  • The screening used a single standard dose of 12.5 mg/ml for all materials.
  • In the same screening, none of the amphibole asbestiform samples (crocidolite, amosite, anthophyllite, tremolite) was substantially active, regardless of physical form. A footnote notes that amphibole hemolysis may occur under different experimental conditions.
  • Among non-asbestiform fibrous materials, all were active except the hand-cut crude samples of nemalite and sepiolite.
  • Magnesium hydroxide and the burned magnesium oxide samples were not hemolytic, except lightly burned MgO.
  • The minimal hemolytic dose for standard UICC chrysotiles A and B was 3.125 mg/ml. The scan prints the unit as 'n&ml', but the article measures doses in mg/ml throughout.
  • In a comparison of one crude (1A) and one air-jet-milled (1E) Jeffrey chrysotile sample, air-jet milling increased hemolytic potency more than 40-fold. Across samples, the minimal hemolytic dose decreased as air permeability surface area increased.
  • EDTA at 2.5 mg/ml and greater inhibited hemolysis by UICC chrysotile B at 6.25 mg/ml. EDTA at 10 mg/ml did not inhibit hemolysis by micro-quartz at the same dose. Other chelating agents failed to inhibit either.
  • Carboxymethylcellulose (CMC), polystyrene sulfonates CRS 773 and CRS 774, and particularly the pyran-copolymer NSC-46015 antagonized chrysotile hemolysis.
  • Methylcellulose and polyvinylpyridine-N-oxide (PVPNO) were substantially less effective against chrysotile. PVPNO showed a marked inhibiting effect on micro-quartz (silica) hemolysis.
  • Tamol SN surface treatment reduced the hemolytic titer of Advocate and Jeffrey chrysotile fibers to 45% and 49.5% respectively.
  • After eight saline washings, hemolysis by air-jet-milled Carey and Cassiar chrysotile was unchanged at 100%. Washing with EDTA also did not eliminate the hemolytic action.
  • Exposure to CMC inactivated UICC chrysotile B irreversibly. Pretreating the red cells with CMC did not prevent hemolysis.
  • Repeated exposure of chrysotile to red cells, with washing between exposures, eliminated hemolytic activity. Some varieties (Jeffrey, Reeves, Arizona, Cassiar) lost most of their activity after one treatment. Chrysotile A and Carey fibers needed two or three exposures.
  • The authors attributed nemalite's intermediate behavior in the inhibitor tests to the presence of chrysotile fibers in the nemalite samples.
• The authors' conclusion: The authors concluded that the hemolytic activity of chrysotile is related to the surface area or degree of opening of the fibers. They added that the mechanism of asbestos hemolysis could not yet be satisfactorily interpreted. They suggested further in vivo work with chrysotile and polymers that have high antihemolytic activity.
• Limitations the authors state:
  • The authors stated that no relationship is known between hemolysis observations and the disease-causing potential of the minerals.
  • The authors noted that amphibole minerals may cause hemolysis under different experimental conditions, which were under study.
  • The authors could not say whether the relationship reflects fiber size or exposed surface area.
  • This hemolysis work did not include fiber length, which the authors describe as appearing essential in fibrosis studies.
  • Complete titrations of the inhibitors on nemalite were not available.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Cassiar mine, British Columbia
• Jeffrey mine, Asbestos, Quebec

All asbestos mines

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Amphibole Group, Asbestiform, Crocidolite, Amosite, Tremolite, Anthophyllite, Non-Asbestiform.

Related studies

• Interrelationship between hemolysis and lipid peroxidation of human erythrocytes induced by silicic acid and silicate dusts — S.V. Singh, Q. Rahman (1987)
• Hemolysis by asbestos — J.S. Harington, K. Miller, et al. (1971)
• Haemolytic activity of asbestos and other mineral dusts — G. Macnab, J.S. Harington (1967)
• A comparative study on the hemolytic action of short asbestos fibers on human, rat, and sheep erythrocytes — J.P. Pelé, R. Calvert (1983)
• The prevention of asbestos-induced hemolysis — R. Desai, P. Hext, et al. (1975)
• Hemolysis by chrysotile asbestos fibers. I. Influence of the sialic acid content in human, rat, and sheep red blood cell membranes — J.P. Pelé, R. Calvert (1983)

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