Asbestos-mediated membrane uptake of benzo\[a\]pyrene observed by fluorescence spectroscopy

Our plain-English summary of Asbestos-mediated membrane uptake of benzo[a]pyrene observed by fluorescence spectroscopy, by J.R. Lakowicz, J.L. Hylden (Nature, 1978).

The study

• Authors: J.R. Lakowicz, J.L. Hylden
• Journal: Nature
• Published: 1978;275(5679):446-8
• Cited by: 52 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

In plain English

This was a laboratory experiment, not a study of people. The authors used fluorescence spectroscopy to test whether particles could pick up the cancer-causing chemical benzo[a]pyrene (BP) and pass it into model membranes made of artificial phospholipid vesicles. They compared amosite asbestos with silica, loading each with 0.1 to 3.0 mg of BP per gram of particle, and also tested BP crystals with no particles. The amosite had far less surface area than the silica (5.7 versus 381 square metres per gram). Even so, it held BP more as separate, dispersed molecules, while the silica samples consistently gave more signal from BP molecules packed close together. BP carried on amosite moved into the membranes fastest, and plain BP crystals moved slowest. Amosite outperformed silica at every loading tested, most clearly at the lower loadings. Adding particles to BP crystals that had already formed did not speed uptake. The authors concluded this may partially explain how particles and such chemicals together promote cancer, and noted that other mechanisms also operate. The smoking and lung cancer figures in the article's introduction come from earlier studies, not this one.

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 using fluorescence spectroscopy
• Who was studied: No human or animal subjects. Materials tested were amosite asbestos (the only asbestos type used), silica, benzo[a]pyrene, and single-bilayer vesicles of dipalmitoyl-L-alpha-phosphatidylcholine as a model membrane.
• Exposure: Benzo[a]pyrene adsorbed onto amosite or silica at 0.1 to 3.0 mg BP per gram of particle, compared with BP microcrystals without particles
• Main results:
  • The surface area measured by nitrogen adsorption was 5.7 square metres per gram for the asbestos and 381 for the silica, yet the asbestos dispersed BP as single molecules better than silica did.
  • Across BP loadings, the silica samples consistently showed more excimer emission, a signal from adjacent BP molecules, than the asbestos samples.
  • BP adsorbed to asbestos showed the most rapid uptake into the model membranes, and BP microcrystals showed the slowest.
  • Asbestos was more effective than silica at all BP-to-particle weight ratios tested, with the largest effect at the lower ratios.
  • Adding asbestos or silica to BP microcrystals that had already formed did not increase the rate of membrane uptake.
  • Uptake rates increased as the surface density of BP on the particles decreased.
• The authors' conclusion: The authors concluded that the ability of a particle with a known co-carcinogenic effect to disperse and transport benzo[a]pyrene may partially explain the co-carcinogenic effects of particulates and polynuclear aromatic hydrocarbons.
• Limitations the authors state:
  • The authors stated that mechanisms other than particle-enhanced transport are at work in carcinogenesis.
  • The BP spectra on silica samples changed as the samples aged over weeks, and the authors did not know what controls this process.

Related studies

• Effects of asbetos, iron oxide, silica, and carbon black on the microsomal availability of benzo[a]pyrene — J.R. Lakowicz, D.R. Bevan (1979)
• 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)
• Effects of asbestos on membrane transport and metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1980)
• Transport of a carcinogen, benzo[a]pyrene, from particulates to lipid bilayers: a model for the fate of particle-adsorbed polynuclear aromatic hydrocarbons which are retained in the lungs — J.R. Lakowicz, D.R. Bevan, et al. (1980)
• Effects of crocidolite and chrysotile asbestos on cellular uptake and metabolism of benzo(a)pyrene in hamster tracheal epithelial cells — B.T. Mossman, A. Eastman, et al. (1983)
• Effect of chrysotile asbestos and silica on the microsomal metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1983)

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