Tests for effect of asbestos on benzo\[a\]pyrene carcinogenesis in the respiratory tract

Our plain-English summary of Tests for effect of asbestos on benzo[a]pyrene carcinogenesis in the respiratory tract, by L. Miller, W.E. Smith, S.W. Berliner (Annals of the New York Academy of Sciences, 1965).

The study

• Authors: L. Miller, W.E. Smith, S.W. Berliner
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):489-500
• Cited by: 44 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy.

In plain English

This animal experiment tested whether asbestos increased the cancer-causing effect of benzo[a]pyrene, a carcinogen in cigarette smoke, in the respiratory tract of male hamsters. Treated groups received weekly injections into the windpipe. In a pilot experiment, 50 hamsters were split into five groups of ten: benzo[a]pyrene alone, benzo[a]pyrene plus chrysotile, chrysotile alone, the suspending liquid alone, and no treatment. Among hamsters that lived 173 to 214 days, tumors were found in three of five given benzo[a]pyrene alone and in all seven given benzo[a]pyrene plus chrysotile. The benzo[a]pyrene plus chrysotile group also had more tumors per tumor-bearing animal, larger tumors and the most malignant tumors. No tumors were found in the three groups without benzo[a]pyrene. The authors wrote that this suggested chrysotile promoted the carcinogen, but the numbers were too small for a decision. In a second experiment of 80 hamsters, tumors were found at 240 days in 8 of 27 survivors given benzo[a]pyrene alone (29 per cent) and 5 of 19 given it with amosite (26 per cent). The authors concluded amosite did not increase tumor yield. Microscopic study was incomplete.

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 (two experiments, the first a pilot test) using repeated intratracheal injections in hamsters
• Who was studied: Male golden Syrian hamsters, one to two months old at the start: 50 in Experiment 1 (five groups of ten) and 80 in Experiment 2 (40 per group)
• Exposure: Weekly intratracheal injections of 0.5 mg benzo[a]pyrene suspended in aqueous Tween 60. In Experiment 1 (25 weeks) some groups also got 0.25 mg chrysotile per injection; there were also chrysotile-only, Tween-only and untreated groups. In Experiment 2 (16 injections, 8 mg benzo[a]pyrene in total) half of the animals also got 2.5 mg amosite per injection (40 mg in total).
• Main results:
  • Experiment 1: among hamsters given benzo[a]pyrene alone that lived between 173 and 214 days, respiratory tract tumors were found in 3 of 5
  • Experiment 1: tumors were found in all 7 hamsters given benzo[a]pyrene plus chrysotile that were examined in the same period
  • Experiment 1: the benzo[a]pyrene plus chrysotile group had more tumors per tumor-bearing animal and larger tumors than the benzo[a]pyrene-only group
  • Experiment 1: the most malignant tumors were in the benzo[a]pyrene plus chrysotile group. The authors said these criteria suggested a promoting effect of chrysotile, but the numbers were too small to decide.
  • Experiment 1: no respiratory tract tumors were found in untreated hamsters, in those given chrysotile alone, or in those given the suspending medium alone
  • Experiment 2: of the 27 hamsters given benzo[a]pyrene alone that survived to 240 days, 8 had respiratory tract tumors (29 per cent)
  • Experiment 2: of the 19 hamsters given benzo[a]pyrene plus amosite that survived to 240 days, 5 had respiratory tract tumors (26 per cent), each a single papilloma
  • Experiment 2: at 240 days the tumor yields of the two groups were almost identical (29 versus 26 per cent), and no evidence of a promoting action of amosite was found
  • Experiment 2: among benzo[a]pyrene-only hamsters, tumors were found in 7 of 11 examined between 201 and 217 days, but in only 8 of 27 examined at 240 days (about 64 versus 30 per cent)
• The authors' conclusion: The authors concluded that adding chrysotile gave results consistent with the hypothesis that it promoted benzo[a]pyrene carcinogenesis in the respiratory tract. Adding amosite did not increase the tumor yield. They also concluded that the tumor yield after a limited series of benzo[a]pyrene injections decreased with time after exposure stopped, which they considered of interest for smokers who stop smoking.
• Limitations the authors state:
  • In Experiment 1 the numbers of animals were too small to permit a decision about chrysotile
  • In Experiment 1 the benzo[a]pyrene dose was too large for convenient measurement of any cocarcinogenic action of asbestos
  • Histological study of all specimens was not complete, so only tumors seen in gross specimens and then confirmed in histological sections were counted
  • In Experiment 2, deaths before 240 days were hard to compare because the benzo[a]pyrene plus amosite group did not live as long as the benzo[a]pyrene-only group

Topics

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

Related studies

• 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)
• Tests for carcinogenicity of asbestos — W.E. Smith, L. Miller, et al. (1965)
• Presentation of benzo(a)pyrene to microsomal enzymes by asbestos fibers in the Salmonella/mammalian microsome mutagenicity test — K. Szyba, A. Lange (1983)
• 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)
• Asbestos and benzo(a)pyrene synergism in the transformation of Syrian hamster embryo cells — J.A. DiPaolo, A.J. DeMarinis, et al. (1983)
• Morphological transformation of Syrian hamster embryo cells induced by mineral fibres and the alleged enhancement of benzo[a]pyrene — S.O. Mikalsen, E. Rivedal, et al. (1988)

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