Surface charge and hemolytic activity of asbestos

Our plain-English summary of Surface charge and hemolytic activity of asbestos, by W.G. Light, E.T. Wei (Environmental Research, 1977).

The study

• Authors: W.G. Light, E.T. Wei
• Journal: Environmental Research
• Published: 1977;13(1):135-45
• Cited by: 81 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Surface charge, represented by zeta potential, and hemolytic activity were measured for the five asbestos reference samples of the International Union against Cancer (UICC). Zeta potentials in distilled water at pH 7.4 for chrysotiles A and B were +40.5 and +52.5 mV, and for amphiboles crocidolite, amosite, and anthophyllite were -50.4, -58.5, and -54.0 mV, respectively. For fiber samples of equal surface area, chrysotiles had a greater hemolytic activity than amphiboles: 60.5 and 81.9% for chrysotiles A and B compared to 7.7, 9.8, and 15.7% for crocidolite, amosite, and anthophyllite, respectively. A lysing mechanism based on charge polarity is proposed to account for this difference in activity. Zeta potential and hemolytic activity were reduced by adding the main component of pulmonary surfactant, dipalmitoyl phosphatidylcholine (DPPC), to fiber suspensions. DPPC was more effective in decreasing both zeta potential and hemolytic activity for amphiboles than for chrysotiles. On the basis of these reductions, a significant correlation (r = 0.84) was found between zeta potential and hemolytic activity for all five UICC samples. This correlation suggests that surface charge is the principal factor in hemolysis by asbestos. The relevance of surface charge to asbestos toxicity is discussed.

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

In plain English

This laboratory study tested the five International Union against Cancer (UICC) asbestos reference samples: chrysotile A, chrysotile B, crocidolite, amosite and anthophyllite. The authors measured each fiber's surface electrical charge (its 'zeta potential') and how strongly it burst sheep red blood cells (hemolytic activity). In distilled water at pH 7.4 (not the solution used for the red-cell tests), the two chrysotiles carried a positive charge (+40.5 and +52.5 mV) and the three amphiboles a negative charge of similar size (-50.5 to -58.5 mV). With fiber amounts adjusted for surface area, the chrysotiles had higher hemolytic activity (60.5% and 81.9%) than the amphiboles (7.7% to 15.7%). These figures are percentages of the optical-density reading of a fully burst control, not counts of burst cells. Adding DPPC, the main component of lung surfactant, lowered both the charge and the cell-bursting activity, and it did so more for amphiboles than for chrysotiles. The drop in charge and the drop in cell-bursting activity were correlated (r = 0.84, P < 0.01). The authors concluded that this correlation suggests surface charge is the principal factor in hemolysis by asbestos.

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) experiment on asbestos fiber samples and sheep red blood cells
• Who was studied: The five UICC asbestos reference samples (chrysotile A, chrysotile B, crocidolite, amosite, anthophyllite), tested against sheep red blood cells, with six replicate tubes per suspending liquid and fiber type. The work was done at the University of California, Berkeley, and the article was received in March 1976. A glass fiber was also tested in preliminary experiments.
• Exposure: Fiber amounts were adjusted for differences in surface area: 5 mg of each chrysotile, 10 mg of anthophyllite, and 20 mg of crocidolite or amosite. Fibers were tested with and without the lung surfactant component dipalmitoyl phosphatidylcholine (DPPC).
• Main results:
  • Zeta potentials in distilled water at pH 7.4: chrysotile A +40.5 mV, chrysotile B +52.5 mV, crocidolite -50.5 mV, amosite -58.5 mV, anthophyllite -54.0 mV. The two fiber types were similar in size of charge but opposite in polarity.
  • Zeta potential was measured in distilled water rather than Tyrode's solution (the liquid used in the red-cell tests), because salt solutions generate excessive heat in the measuring cell.
  • Hemolytic activity in Tyrode's solution, for fiber samples of equal surface area: chrysotile B 81.9%, chrysotile A 60.5%, anthophyllite 15.7%, amosite 9.8%, crocidolite 7.7%.
  • Hemolytic activity was calculated from average optical density and expressed as a percentage of the optical density of a totally lysed control.
  • At a DPPC-to-fiber ratio of 0.1, zeta potential fell by about 74% for amosite and crocidolite and by about 11% for chrysotiles A and B.
  • At the same ratio, hemolytic activity fell by about 87% for amosite and crocidolite and by about 25% for chrysotiles A and B.
  • Across all five UICC samples, the percentage decrease in zeta potential was correlated with the percentage decrease in hemolytic activity (P < 0.01, r = 0.84).
  • Raising the pH from 7.4 to 7.9 made no significant difference to hemolysis. DPPC on its own did not protect cells from osmotic rupture.
  • In preliminary experiments, a glass fiber ('code 100 microfiber, 475 glass') had a zeta potential of -53.5 mV and a hemolytic activity of 28.3% for 10 mg of fibers.
• The authors' conclusion: The authors concluded that the correlation suggests surface charge is the principal factor in hemolysis by asbestos. They proposed that differences in charge polarity explain why chrysotiles and amphiboles differ in hemolytic activity.

Topics

Medical terms in this study, explained in our Lexicon: UICC, Chrysotile, Amphibole Group, Crocidolite, Amosite, Anthophyllite.

Related studies

• Surface charge and asbestos toxicity — W.G. Light, E.T. Wei (1977)
• The hemolytic activity of chrysotile asbestos fibers: a freeze-fracture study — J.P. Pelé, J. Dunnigan, et al. (1983)
• Mount St. Helens' volcanic ash: hemolytic activity — V. Vallyathan, M.S. Mentnech, et al. (1983)
• A comparative study on the hemolytic action of short asbestos fibers on human, rat, and sheep erythrocytes — J.P. Pelé, R. Calvert (1983)
• Modification of biological surface activity of particles — R.J. Schnitzer (1974)
• The prevention of asbestos-induced hemolysis — R. Desai, P. Hext, et al. (1975)

Browse more research in Environmental Research, or return to medical research.