Presentation of benzo(a)pyrene to microsomal enzymes by asbestos fibers in the Salmonella/mammalian microsome mutagenicity test

Our plain-English summary of Presentation of benzo(a)pyrene to microsomal enzymes by asbestos fibers in the Salmonella/mammalian microsome mutagenicity test, by K. Szyba, A. Lange (Environmental Health Perspectives, 1983).

The study

• Authors: K. Szyba, A. Lange
• Journal: Environmental Health Perspectives
• Published: 1983;51:337-41
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The potential effect of asbestos fibers on mutagenicity of benzo(a)pyrene was investigated by using the Ames test. Asbestos fibers without a coating of benzo(a)pyrene or benzo(a)pyrene when not dissolved in DMSO lacked any mutagenic effect in the Salmonella/mammalian microsome mutagenicity test. However, when benzo(a)pyrene was adsorbed onto asbestos, significant numbers of mutated bacteria were observed. This shows that asbestos fibers can serve a carrier role presenting benzo(a)pyrene to the enzymatic microsomal system, thus enhancing mutagenicity of this compound.

In plain English

This was a laboratory experiment using the Ames test (Salmonella/mammalian microsome mutagenicity test) with S. typhimurium strains TA 98 and TA 100 and a liver S-9 fraction from Aroclor 1254-treated male Wistar rats. UICC amosite, crocidolite and chrysotile were tested alone, and with benzo(a)pyrene (BaP) adsorbed onto the fibers by two methods, alongside BaP dissolved in DMSO and an aqueous microcrystalline BaP suspension. Asbestos fibers alone produced no significant increase in revertants over 1 to 20 mg/plate, with or without S-9, and microcrystalline BaP without DMSO was also non-mutagenic. BaP adsorbed onto fibers by the Lakowicz and Hylden method gave significant increases in revertants (for amosite with TA 100: 194 plus or minus 10 with no BaP, 582 plus or minus 21 at 5 micrograms, 968 plus or minus 75 at 10 micrograms), comparable to BaP in DMSO, for all three fiber types; adsorption by the Kandaswami and O'Brien method gave none. The authors concluded asbestos fibers can act as a carrier presenting BaP to the microsomal enzyme system, enhancing its mutagenicity.

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: In vitro bacterial mutagenicity experiment (Ames test) with rat liver microsomal activation
• Who was studied: Salmonella typhimurium histidine auxotroph strains TA 98 and TA 100 carrying plasmid pKM 101, with S-9 liver fraction from Aroclor 1254-treated male Wistar rats; work done at the Institute of Immunology and Experimental Therapy, Wroclaw, Poland
• Exposure: UICC asbestos samples (amosite, crocidolite, chrysotile), alone or coated with benzo(a)pyrene by two adsorption methods; BaP dissolved in DMSO and aqueous microcrystalline BaP as comparison; asbestos 1 to 20 mg/plate, BaP doses of 1.5, 3.0, 5, 6.0 and 10 micrograms per plate
• Main results:
  • Asbestos fibers alone caused no significant increase in mutated bacteria, from 1 to 20 mg/plate, with or without the S-9 fraction
  • BaP in DMSO was mutagenic in TA 100 (201 plus or minus 10 with no BaP, 603 plus or minus 44 at 5 micrograms/plate), while microcrystalline BaP without DMSO was not
  • With BaP adsorbed onto amosite by the Lakowicz and Hylden method in TA 100, revertants rose from 194 plus or minus 10 (no BaP) to 582 plus or minus 21 at 5 micrograms and 968 plus or minus 75 at 10 micrograms per plate, with correlation coefficient 0.966
  • The increase with fiber-adsorbed BaP was comparable to BaP in DMSO and similar for amosite, chrysotile and crocidolite
  • BaP adsorbed by the Kandaswami and O'Brien method showed no mutagenicity
  • In dose-response experiments a significant increase in revertants appeared at the 1.5 microgram BaP dose with all three fiber types and in both strains; correlation coefficients with TA 100 were 0.96 (chrysotile), 0.93 (amosite) and 0.94 (crocidolite), and with TA 98 0.91, 0.81 and 0.94
• The authors' conclusion: The authors concluded that asbestos fibers can act as a carrier presenting benzo(a)pyrene to the microsomal enzyme system, thereby enhancing its mutagenicity

Related studies

• Effect of chrysotile asbestos and silica on the microsomal metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1983)
• 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 asbetos, iron oxide, silica, and carbon black on the microsomal availability of benzo[a]pyrene — J.R. Lakowicz, D.R. Bevan (1979)
• Effect of particulates on metabolism and mutagenicity of benzo[a]pyrene — D.R. Bevan, W.E. Manger (1985)
• Enhancement of benzo[a]pyrene mutagenicity by chrysotile asbestos in rat liver epithelial cells — B. Reiss, C. Tong, et al. (1983)
• Effects of asbestos on membrane transport and metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1980)

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