Interactions of mineral fiber surfaces with cells in vitro

Our plain-English summary of Interactions of mineral fiber surfaces with cells in vitro, by R.J. Schnitzer, G. Bunescu, V. Baden (Annals of the New York Academy of Sciences, 1971).

The study

• Authors: R.J. Schnitzer, G. Bunescu, V. Baden
• Journal: Annals of the New York Academy of Sciences
• Published: 1971;172(23):759-72
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy.

In plain English

This was a laboratory study of cells, not of people. The authors exposed washed red blood cells from sheep, horses and humans to asbestos and other mineral fibers, measured how many cells burst (hemolysis), and tested substances that might block this. They also ran preliminary, qualitative tests of whether bacteria survived on fibers. Chrysotile burst red cells of every species tested. For the UICC chrysotile B sample, half the cells burst at 0.11 to 0.27 mg/ml, and potency among chrysotile samples varied with fiber openness. Amphibole fibers (amosite, crocidolite, anthophyllite) caused consistent bursting when gently shaken in a shallow layer, with potency rising from amosite to crocidolite to anthophyllite. Negatively charged polymers blocked chrysotile hemolysis, while uncharged polymers blocked silica (microquartz) hemolysis. E. coli could not be recovered after one to three days on most chrysotile samples, and amphiboles also acted against Staph. aureus. The authors found no convincing link between the two effects. They concluded that seemingly inert mineral fibers and dusts can react with cells and destroy them, and called their explanation of hemolysis conjectural.

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) experiments: red blood cell hemolysis tests with inhibitor tests, plus preliminary qualitative tests of bacterial survival on fibers
• Who was studied: Washed red blood cells from sheep, horses and humans, used at 2% concentration; for the antibacterial tests, E. coli B, Staph. aureus 209P and, in a few experiments, enterococci
• Exposure: Chrysotile (UICC standard sample and samples from the Jeffrey, Munro, Coalinga and Advocate sources), amosite, crocidolite and anthophyllite at various degrees of fiber openness (crude, hammer-milled, air-jet-milled), plus microquartz, fibrous talc, palygorskite, nemalite and magnesium hydroxide, at concentrations measured in mg/ml
• Main results:
  • Chrysotiles caused hemolysis of all cell species tested
  • For the UICC chrysotile B sample, the 50% hemolytic concentrations were 0.11 to 0.27 mg/ml, including sheep cells
  • For chrysotile B, the 50% hemolytic concentration for horse cells was 0.27 mg/ml
  • Differences in potency among chrysotile samples depended on fiber openness, as expressed by surface area
  • The 50% inhibiting concentration of EDTA against chrysotile hemolysis varied between 1.3 mg/ml and 1.85 mg/ml depending on the chrysotile sample
  • Polyanions (negatively charged polymers such as carboxymethylcellulose and sodium alginate) acted as chrysotile antagonists, while nonionic polymers acted as silica antagonists
  • Silica (microquartz) caused hemolysis of sheep and human cells only at comparatively high concentrations: 50% hemolytic concentration 2.2 to 3.3 mg/ml for quartz and 4.7 mg/ml for silicic acid
  • Amphibole fibers exposed to red cells in a shallow layer with gentle agitation at 37 degrees C caused consistent lysis
  • For amphibole fibers in a shallow layer, agitation increased hemolysis, and human cells were more sensitive than sheep cells
  • 50% hemolytic concentrations for amphiboles were more than 10 mg/ml for amosite, 3.0 to 7.0 mg/ml for crocidolite and 1.0 to 3.0 mg/ml for anthophyllite
  • Anthophyllite hemolysis was inhibited by the chrysotile inhibitors carboxymethylcellulose and sodium alginate, and also by PVP, a silica antagonist
  • Pure magnesium hydroxide was not lytic for sheep cells, or only at a high level, but readily lysed horse and human cells (50% hemolytic concentration 0.56 to 4.5 mg/ml)
  • Nemalite, an impure fibrous brucite containing up to 33.46% chrysotile, caused hemolysis that the authors judged was most likely due to its chrysotile portion
  • E. coli could not be recovered after one to three days on chrysotile fibers, except on the crude Munro chrysotile
  • Apart from a slow effect of the UICC chrysotile mixture, chrysotile activity was limited to the gram-negative E. coli and did not extend to gram-positive cocci
  • Amphibole fibers showed marked antimicrobial action against both gram-negative and gram-positive organisms
  • The order of antimicrobial effect among amphiboles was the reverse of their hemolytic order: anthophyllite less than crocidolite less than amosite
  • The authors found no convincing correlation between hemolytic and antibacterial action
  • Test bacteria grew abundantly when chrysotile or amosite was present in nutrient media, and the authors stated that close contact of fibers and organisms seemed essential
• The authors' conclusion: The authors concluded that seemingly inert mineral fibers and dusts can react with cells and exert toxic effects that destroy the cells
• Limitations the authors state:
  • The antibacterial studies were preliminary and qualitative
  • The antimicrobial work was limited to vegetative aerobic bacteria
  • The interpretation of how hemolysis happens is still conjectural
  • Knowledge of what blocks the antibacterial action of fibers is incomplete
  • Hemolysis by asbestos fibers has not been definitely shown in living organisms
  • The low hemolytic potency of amosite made inhibitor tests difficult

Topics

Medical terms in this study, explained in our Lexicon: Mineral Fiber.

Related studies

• Haemolytic activity of asbestos and other mineral dusts — G. Macnab, J.S. Harington (1967)
• Hemolysis by asbestos — J.S. Harington, K. Miller, et al. (1971)
• Wollastonite fibers in vitro generate reactive oxygen species able to lyse erythrocytes and activate the complement alternate pathway — M. Governa, L. Camilucci, et al. (1998)
• Synthetic silica fibers of different length, diameter and shape: synthesis and interaction with rat (NR8383) and human (THP-1) macrophages in vitro, including chemotaxis and gene expression profile — N. Białas, N. Rosenkranz, et al. (2024)
• A comparative study on the hemolytic action of short asbestos fibers on human, rat, and sheep erythrocytes — J.P. Pelé, R. Calvert (1983)
• Pulmonary cell interactions with asbestos fibers in vivo and in vitro — A.R. Brody (1986)

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