Adsorption of benzo(a)pyrene on to asbestos and manmade mineral fibres in an aqueous solution and in a biological model solution

Our plain-English summary of Adsorption of benzo(a)pyrene on to asbestos and manmade mineral fibres in an aqueous solution and in a biological model solution, by P. Gerde, P. Scholander (British Journal of Industrial Medicine, 1988).

The study

• Authors: P. Gerde, P. Scholander
• Journal: British Journal of Industrial Medicine
• Published: 1988;45(10):682-8
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The adsorption of benzo(a)pyrene (BaP) on to three types of asbestos (chrysotile antophyllite, and amosite) and three types of manmade mineral fibres (MMMF) (rock wool, slag wool, and glass wool) in a physiological water solution was studied. Adsorption was determined from the decrease in the liquid concentration of BaP on the addition of the solid material. Results show that all the fibres weakly adsorb BaP, approximately within the same order of magnitude. The combined adsorption of BaP and phosphatidylcholine (PC) on to chrysotile and amosite asbestos and on to rock wool in aqueous solution was also studied. PC, one of the major constituents in lung surfactant, forms a separate lipid phase in water consisting of micellar liposomes or lipid bilayers. A decrease in the liquid concentration of PC was found when any of the three materials was added, indicating adsorption of the lipid phase on to the fibres. A coincident decrease in the liquid concentration of BaP was also found indicating that BaP is readily solubilised in PC and will accompany the adsorption of this compound on to the fibres. Owing to the high lipid aqueous partition coefficient of BaP, it is concluded that the direct adsorption of BaP on to the fibres will be negligible when PC is present in the system even at low concentrations. Phospholipid adsorption by the fibres and not their direct adsorption of aromatic hydrocarbons should therefore be the crucial parameter for this indirect interaction between fibres and aromatic hydrocarbons.

In plain English

This laboratory study tested whether benzo(a)pyrene (BaP) sticks to mineral fibres in physiological salt solution. BaP is a polycyclic aromatic hydrocarbon (PAH), a group the authors describe as cancer-causing compounds in tobacco smoke. They tested three asbestos types (chrysotile, antophyllite, amosite) and three manmade mineral fibres (rock, slag and glass wool). They measured how much BaP left the liquid after adding fibres. All six adsorbed BaP only weakly, within the same order of magnitude per surface area. Tests with amosite, chrysotile and rock wool then added phosphatidylcholine (PC), a major part of lung surfactant, and all three fibres adsorbed PC. This adsorption changed over time on chrysotile and rock wool but was much more stable on amosite. BaP dissolved into the PC and followed it on to the fibres. In one amosite test, the liquid lost 75% of its BaP and 60% of its PC. The authors concluded that direct PAH adsorption on to fibres in the lung is negligible, and that the fibres' phospholipid adsorption should be the crucial factor. They noted that their method cannot exactly estimate lung phospholipid adsorption.

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 measuring adsorption by the solution depletion method; no people or animals were studied
• Who was studied: Fibre samples, not people: three asbestos types (chrysotile, antophyllite, amosite; UICC samples) and three manmade mineral fibres (rock wool, slag wool, glass wool), tested at the Royal Institute of Technology, Stockholm, Sweden
• Exposure: Radioactively labelled benzo(a)pyrene (BaP) in a physiological water solution (Gamble type II), alone and together with labelled phosphatidylcholine (PC), the most common phospholipid in lung surfactant
• Main results:
  • In water solution without PC, all six fibres adsorbed BaP weakly. Adsorption per surface area was within the same order of magnitude for all materials tested.
  • Amosite, chrysotile and rock wool, the fibres for which PC results are reported, all adsorbed PC
  • PC adsorption changed over time on rock wool and chrysotile. Amosite had a much more stable adsorption of PC by comparison.
  • When PC was present, the authors attributed the drop in BaP to BaP dissolving into PC layers adsorbed on the fibres, not to direct adsorption on to the fibres
  • In one amosite batch, adding fibres reduced the liquid concentration of BaP by 75% and of PC by 60%. In that case the BaP concentration in lipids adsorbed on fibres was twice that in free liposomes.
• The authors' conclusion: The authors concluded that direct adsorption of polycyclic aromatic hydrocarbons on to mineral fibres in the lung is negligible. They concluded that the fibres' adsorption of phospholipids, not their direct adsorption of aromatic hydrocarbons, should be the crucial parameter for the indirect interaction between fibres and these hydrocarbons.
• Limitations the authors state:
  • The solution depletion method is not suitable for exact estimation of phospholipid adsorption on to fibres in the lung
  • The maximum possible ratio of PC to fibres was far too low to simulate true conditions around a single fibre in the lung
  • Experiments with PC were run at 41°C rather than 37°C. The authors judged that this probably had only a limited influence on the results.

Topics

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

Related studies

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• Benzo[a]pyrene-enhanced mutagenesis by man-made mineral fibres in the lung of lamda-lacI transgenic rats — J. Topinka, P. Loli, et al. (2006)
• Pulmonary response of hamsters to fibrous glass: chronic effects of repeated intratracheal instillation with or without benzo[a]pyrene — V.J. Feron, P.M. Scherrenberg, et al. (1985)
• Benzo[a]pyrene uptake into rat liver microsomes: effects of adsorption of benzo[a]pyrene to asbestos and non-fibrous mineral particulates — J.R. Lakowicz, D.R. Bevan (1980)
• Chromosomal changes induced by chrysotile fibres or benzo-3,4-pyrene in rat pleural mesothelial cells — M.C. Jaurand, L. Kheuang, et al. (1986)
• In vitro transformation of rat pleural mesothelial cells by chrysotile fibres and/or benzo[a]pyrene — M.J. Paterour, J. Bignon, et al. (1985)

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