Calculated solubility of chrysotile asbestos in physiological systems

Our plain-English summary of Calculated solubility of chrysotile asbestos in physiological systems, by W.T. Parry (Environmental Research, 1985).

The study

• Author: W.T. Parry
• Journal: Environmental Research
• Published: 1985;37(2):410-8
• Type of article: Review
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Chrysotile asbestos fibers which are ingested into a physiological system will dissolve in fluids to which they are exposed. The rate of dissolution can be estimated by formulating an appropriate rate law and retrieving rate constants from published experiments. The rate of dissolution calculated for asbestos fibers is dependent on the surface area of dissolving mineral, mass of solution to which the fibers are exposed within cells, the rate of transport of H+ into the cells, and the rate of transport of Mg2+ and SiO2 out of the cells. The maximum rate of dissolution of a single 10-micron X 1-micron fiber within a cell is 2.13 X 10(-7) moles hr-1 kg-1 consistent with dissolution rates measured in vivo by Morgan et al. (A. Morgan, A. Holmes, and C. Gold. Studies of the solubility of constituents of chrysotile asbestos in vivo using radioactive tracer techniques. Environ. Res. 4, 558-570, 1971).

In plain English

This was a theoretical calculation, not a study of people or animals. The author combined a published rate law for silicate mineral dissolution with rate constants from earlier laboratory experiments to estimate how fast chrysotile asbestos dissolves inside a cell. The model used one chrysotile fiber 10 micrometers long and 1 micrometer wide inside a cell 20 micrometers across, and assumed simplified chemical transport across the cell membrane. The calculated maximum dissolution rate was 2.13 x 10^-7 moles per hour per kilogram of cell fluid. At the maximum rates, dissolving 30% of the fiber took about 3 years, or about 6 months if plasma was at quartz saturation. For one hundred thinner fibers with the same total mass, the times were 3.5 and 0.6 months. The author reported these rates were approximately consistent with measurements in rats from an earlier study by Morgan and colleagues (1971). The author concluded that the rate depends on fiber surface area, the amount of cell fluid, and transport into and out of the cell. The author noted that the effects of enzymes and fiber coatings were unknown.

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: Theoretical/computational modeling study: a published mineral dissolution rate law combined with rate constants taken from earlier laboratory dissolution experiments, used to predict chrysotile dissolution in cells; presented as a revision of the author's earlier (1983) estimate
• Who was studied: No human or animal subjects; a modeled single chrysotile fiber (10 micrometers long, 1 micrometer diameter) inside the cytoplasm of a cell 20 micrometers in diameter, which the author stated contains 4.19 x 10^-12 kg of solution
• Exposure: Chrysotile asbestos (serpentine) dissolving in cell fluid; the rate constant was estimated at body temperature (37°C) using an assumed activation energy of 35 kJ/mole
• Main results:
  • For the single 10 x 1 micrometer fiber, the calculated maximum dissolution rate was 2.13 x 10^-7 moles per hour per kilogram of reacting solution, that is, the fluid inside the cell (the article defines its mass term as the mass of reacting solution; the exponent is damaged by OCR in the article text and confirmed by the abstract)
  • At these maximum rates, dissolving 30% of the single chrysotile fiber was estimated to take 2.5 x 10^4 hours, or about 3 years
  • If plasma was maintained at quartz saturation, 30% of the single fiber was estimated to dissolve in 4.5 x 10^3 hours, or about 6 months
  • For one hundred fibers 10 micrometers long and 0.1 micrometer in diameter (same total mass as the single fiber, 10 times the surface area), dissolving 30% was estimated to take 3.5 months and 0.6 months at the two dissolved silica levels
  • The calculated rates were described as approximately consistent with magnesium leaching from chrysotile measured in rats in an earlier study by Morgan et al. (1971); these are that study's measurements, not new ones
• The authors' conclusion: The author concluded that the rate of chrysotile dissolution in a macrophage cell is determined by fiber surface area, the mass of solution in the cell, and the rates of transport of dissolution products out of and hydrogen ion into the cell. The author also stated that the method should be applicable to amphibole, zeolite or other minerals.
• Limitations the authors state:
  • The effects of enzymes, protein coatings and ferruginous bodies on the fiber surface are not known, and concentrations of dissolved silica, magnesium and hydrogen ion are not precisely known
  • The activation energy for serpentine dissolution is not known, so a value was assumed
  • Transport mechanisms for dissolved silica across cell membranes are not known; a full treatment of membrane transport was beyond the scope of the paper, and simple first-order transport was assumed

Topics

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

Related studies

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• An overview of the role of mineral solubility in silicosis and asbestosis — G. Erdogdu, V. Hasirci (1998)
• Solubility of asbestos and man-made mineral fibers in vitro and in vivo: its significance in lung disease — A. Morgan, A. Holmes (1986)
• In vitro cytotoxicity of oxide nanoparticles: comparison to asbestos, silica, and the effect of particle solubility — T.J. Brunner, P. Wick, et al. (2006)
• Solubility of rockwool fibres in vivo and the formation of pseudo-asbestos bodies — A. Morgan, A. Holmes (1984)
• Cytotoxicity and solubility evaluation of two types of whiskers by cell magnetometry — Y. Kudo, Y. Aizawa (2011)

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