Studies of carcinogenesis of asbestos fibers and their natural oils

Our plain-English summary of Studies of carcinogenesis of asbestos fibers and their natural oils, by J.S. Harington, F.J. Roe (Annals of the New York Academy of Sciences, 1965).

The study

• Authors: J.S. Harington, F.J. Roe
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):439-50
• Cited by: 53 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 1965 paper mainly discussed how asbestos might cause cancer. The mechanisms considered were oils carried on the fibers, metals in the fibers, and an effect of inert material lingering in tissue. The paper also reported early results from the authors' own animal work. They extracted natural oils from crocidolite and amosite at about 0.3 per cent of fiber weight. Amosite oil held more polycyclic hydrocarbons, and the authors judged benzo[a]pyrene levels too low to play more than a minor role. In mice injected under the skin with native crocidolite, amosite or chrysotile, or with solvent-extracted crocidolite or amosite, no injection-site tumors had appeared so far. The authors stressed these experiments were incomplete. In skin tests of two jute-manufacturing oils, 20 male mice given one dose of the carcinogen DMBA, then light mineral oil for 20 weeks, developed 118 benign tumors in total; the text reports 8 malignant tumors, but the article's table appears to show 3. Twenty mice given DMBA alone developed one papilloma over 45 weeks. The authors concluded that storing asbestos in jute bags may introduce a significant variable into tests of its carcinogenic activity.

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: Discussion paper on possible mechanisms of asbestos carcinogenesis, with chemical analyses and preliminary results of ongoing animal experiments (mice and rats)
• Who was studied: Laboratory animals at the Chester Beatty Research Institute, London: BALB/C and CBA mice injected under the skin, rats injected into the chest cavity, and groups of 20 male Chester Beatty Stock Strain mice in skin tests
• Exposure: Native crocidolite, amosite and chrysotile fibers; crocidolite and amosite after extraction with 8 solvents; natural oils extracted from crocidolite and amosite with petroleum ether; two oils used in jute manufacture (light mineral oil and "soluble" oil), with or without a prior single dose of DMBA
• Main results:
  • Natural oils were extracted from crocidolite and amosite at yields of approximately 0.3 per cent of crude fiber weight
  • More polycyclic hydrocarbons were detected in the amosite oil than in the crocidolite oil. The benzo[a]pyrene content was printed as 1 per 100 g of fiber for crocidolite and 5 per 100 g for amosite (unit garbled in the scan)
  • In BALB/C mice (10 months) and CBA mice (15 weeks) injected under the skin, no injection-site tumors had appeared so far. Native crocidolite, amosite and chrysotile were tested, as were solvent-extracted crocidolite and amosite
  • Fibrosis was felt at injection sites in some CBA mice, especially in the chrysotile groups. For amosite and crocidolite there was no difference between crude and extracted samples
  • In preliminary tests, the crocidolite and amosite oils did not irritate mouse skin
  • Group 1 (a group of 20 male mice given DMBA, then light mineral oil used in jute manufacture) developed a total of 118 benign skin tumors during 20 weeks of oil treatment. The text gives 8 malignant tumors, but the garbled Table 2 appears to list 3 carcinomata. The authors took this as considerable tumor-promoting activity
  • In Group 3 (a group of 20 mice given DMBA only), one skin papilloma arose during 45 weeks of observation after DMBA
  • The "soluble" jute oil showed no tumor-promoting activity
  • Light mineral oil alone (Group 4): three of 17 survivors developed four benign papillomata by week 20. The authors judged the oil probably weakly carcinogenic. Group 5 ("soluble" oil alone) had no skin tumors
  • A sample of silica powder that had induced pleural mesotheliomata in rats contained approximately 0.06 per cent iron
• The authors' conclusion: The authors concluded that storing asbestos in jute bags may introduce a significant variable into tests of its carcinogenic activity, that benzo[a]pyrene in the natural oils probably plays no more than a minor role, and that asbestos carcinogenesis is unlikely to be an example of the Oppenheimer Effect
• Limitations the authors state:
  • The injection experiments were incomplete when reported
  • The skin tests of asbestos oils were at a very early stage
  • Limited facilities meant the animal experiments had only recently begun

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Lung cancer, Mesothelioma.

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

Related studies

• Tumour initiation by natural and contaminating asbestos oils — F.J. Roe, M.A. Walters, et al. (1966)
• Chemical studies of asbestos — J.S. Harington (1965)
• Fiber carcinogenesis: epidemiologic observations and the Stanton hypothesis — J.S. Harington (1981)
• A comparison of asbestos fiber potency and elongate mineral particle (EMP) potency for mesothelioma in humans — D.H. Garabrant, S.T. Pastula (2018)
• Tests for effect of asbestos on benzo[a]pyrene carcinogenesis in the respiratory tract — L. Miller, W.E. Smith, et al. (1965)
• Implications of multiple mechanisms of carcinogenesis for short-term testing — B.L. Harper, D.L. Morris (1984)

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