Examination of factors that may influence disposition of benzo\[a\]pyrene in vivo: vehicles and asbestos

Our plain-English summary of Examination of factors that may influence disposition of benzo[a]pyrene in vivo: vehicles and asbestos, by D.R. Bevan, M.R. Ulman (Cancer Letters, 1991).

The study

• Authors: D.R. Bevan, M.R. Ulman
• Journal: Cancer Letters
• Published: 1991;57(2):173-9
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Effects of vehicles and of asbestos on disposition of benzo[a]pyrene (B[a]P) were examined in vivo. [3H]B[a]P dissolved in triethylene glycol, ethyl laurate, or tricaprylin was intratracheally administered to male Sprague-Dawley rats. Excretion was most rapid when triethylene glycol was the vehicle, with 70.5% of the recovered dose appearing in bile in 6 h. Lower amounts were excreted into bile when ethyl laurate (58.4%) or tricaprylin (56.2%) were the vehicles, with comparably higher amounts remaining in lungs. When chrysotile asbestos was intratracheally instilled 24 h prior to instillation of [3H]B[a]P dissolved in triethylene glycol, the rate of excretion of radioactivity was slower than without asbestos pretreatment, with only 61.8% of the dose appearing in bile in 6 h.

In plain English

This animal experiment instilled tritium-labelled benzo[a]pyrene ([3H]B[a]P) into the trachea of male Sprague-Dawley rats fitted with bile duct and tracheal cannulas, measuring radioactivity in bile over 6 h and in organs at 6 h. The dose was 1 microgram per kg body weight of total B[a]P in 25 microlitres of triethylene glycol, ethyl laurate, or tricaprylin. Of the recovered dose, 70.5 percent appeared in bile with triethylene glycol (mean with range 2.9, two animals), versus 58.4 percent for ethyl laurate and 56.2 percent for tricaprylin (means with standard deviations 2.2 and 4.3, three animals each), both significantly different from triethylene glycol (P less than 0.05), with comparably higher amounts remaining in lungs (2.6 percent with triethylene glycol). When 1 mg UICC chrysotile asbestos was instilled 24 h beforehand, bile excretion fell to 61.8 percent, which the authors reported as significantly lower, while the higher average lung amount was not statistically significant. The authors concluded that, under these conditions, chrysotile asbestos did not produce large alterations in B[a]P disposition. Groups contained only two to four animals.

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: animal experiment (in vivo disposition study in rats)
• Who was studied: Male Sprague-Dawley rats, 200-250 g, with bile duct and tracheal cannulas, from the Va Tech Laboratory Animal Vivarium
• Exposure: Intratracheal [3H]B[a]P (1 microgram/kg body weight of total B[a]P in 25 microlitres) dissolved in triethylene glycol, ethyl laurate, or tricaprylin; in some experiments 1 mg UICC chrysotile asbestos in 0.5 ml water instilled intratracheally 24 h before B[a]P
• Main results:
  • Bile excretion over 6 h was greatest with triethylene glycol: 70.5% of the dose
  • Lower bile excretion over 6 h with ethyl laurate (58.4%) and tricaprylin (56.2%)
  • Table values are the percent of recovered dose, given as mean with range for triethylene glycol (2 animals) and mean with standard deviation for ethyl laurate and tricaprylin (3 animals each)
  • The ethyl laurate and tricaprylin values in the vehicle table were significantly different from the triethylene glycol values (P less than 0.05)
  • With ethyl laurate and tricaprylin, more radioactivity remained in the lungs than with triethylene glycol, which left 2.6% in lungs
  • After chrysotile pretreatment, only 61.8% of the dose appeared in bile in 6 h, a slower rate of excretion than without asbestos pretreatment
  • The cumulative bile amount at 6 h in asbestos-treated rats was significantly lower than in rats not given asbestos
  • The difference in average lung amounts between asbestos-pretreated and untreated rats was not statistically significant
  • Biliary elimination half-lives without asbestos pretreatment were 31.0 and 100 min
  • Biliary elimination half-lives with asbestos pretreatment were 43.8 and 101 min, the lower 6 h cumulative amount reflecting slower excretion at earlier times
  • Group sizes in the asbestos comparison were 2 animals without pretreatment and 4 with asbestos pretreatment
• The authors' conclusion: The authors concluded that, under the conditions of these experiments, chrysotile asbestos did not produce large alterations in the disposition of B[a]P
• Limitations the authors state:
  • Only total radioactivity was measured, without distinguishing unmetabolized B[a]P from metabolites
  • In the vehicle comparison, lung amounts were evaluated only at 6 h
  • Because a biliary cannula was implanted, eliminated amounts could not be compared directly with another study

Topics

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

Related studies

• Effect of particulates on metabolism and mutagenicity of benzo[a]pyrene — D.R. Bevan, W.E. Manger (1985)
• In vitro transformation of rat pleural mesothelial cells by chrysotile fibres and/or benzo[a]pyrene — M.J. Paterour, J. Bignon, et al. (1985)
• Asbestos and benzo[a]pyrene act synergistically to induce squamous metaplasia and incorporation of [3H]thymidine in hamster tracheal epithelium — B.T. Mossman, A. Eastman, et al. (1984)
• Ascorbic acid inhibits the squamous metaplasia that results from treatment of tracheal explants with asbestos or benzo[a]pyrene-coated asbestos — G. Holtz, E. Bresnick (1988)
• Chromosomal changes induced by chrysotile fibres or benzo-3,4-pyrene in rat pleural mesothelial cells — M.C. Jaurand, L. Kheuang, et al. (1986)
• Sister chromatid exchanges in rat pleural mesothelial cells treated with crocidolite, attapulgite, or benzo 3-4 pyrene — S. Achard, M. Perderiset, et al. (1987)

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