Tests for carcinogenicity of asbestos

Our plain-English summary of Tests for carcinogenicity of asbestos, by W.E. Smith, L. Miller, R.E. Elsasser, et al (Annals of the New York Academy of Sciences, 1965).

The study

• Authors: W.E. Smith, L. Miller, R.E. Elsasser, D.D. Hubert
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):456-88
• Cited by: 74 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy.

Summary of the article

The authors tested whether asbestos causes tumors in animals. They used male golden Syrian hamsters, about two months old at the start, at the Health Research Institute, Fairleigh Dickinson University, New Jersey. Samples of harsh chrysotile, soft chrysotile and amosite were prepared to remove rock dust. In Experiment A, 60 hamsters were divided into four groups of 15. Three groups each received a single intrapleural injection of 25 mg of one sample plus one per cent asbestos in the diet: soft chrysotile for the two chrysotile groups and amosite for the amosite group. The fourth group was an untreated control. Animals lived out their natural lives unless sacrificed, and all were examined at necropsy. The injections produced granulomatous inflammation, necrosis, calcification and thick fibrous pleural adhesions. Pleural mesotheliomas were found at 244, 358 and 482 days after amosite and at 419 and 527 days after harsh chrysotile, but not after soft chrysotile. A sarcoma arose around a subcutaneous deposit of soft chrysotile. No tumors were found in the controls. Gastric ulcers, a lymphoma and a cholangiocarcinoma in asbestos-fed animals may have been spontaneous. In Experiments B and C, repeated weekly intratracheal injections produced lung lesions resembling asbestosis but, so far, no respiratory tumors, and many animals were still alive. The authors concluded that asbestos can induce mesotheliomas in hamsters. They questioned whether this reflects a primary carcinogenic action or a nonspecific effect of fibrosis.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This animal experiment tested whether asbestos causes tumors in male golden Syrian hamsters about two months old. In one experiment, three groups of 15 hamsters each received a single 25 mg injection of harsh chrysotile, soft chrysotile or amosite into the chest (pleural) cavity, and a fourth group of 15 was an untreated control. The injected groups also ate feed containing one per cent asbestos. Other hamsters received repeated doses of the same samples into the windpipe. After pleural injection, all three samples caused thick fibrous adhesions. Pleural mesotheliomas appeared 244, 358 and 482 days after amosite injection and 419 and 527 days after harsh chrysotile injection, but not after soft chrysotile injection. No tumors were found in the untreated controls. No respiratory tract tumors had been found in hamsters injected into the windpipe, though many were still alive. Tumors in hamsters fed asbestos may have been spontaneous. The authors concluded that asbestos can induce mesotheliomas in hamsters. They asked whether this reflects a direct cancer-causing action of the fibers or a nonspecific effect of fibrosis. They noted that injection into the chest cavity does not reproduce human exposure.

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 (long-term tests in hamsters using intrapleural injection, intratracheal injection and feeding of asbestos)
• Who was studied: Male golden Syrian hamsters about two months old at the start, from a commercial breeder in Newfield, New Jersey. Experiment A used 60 hamsters (four groups of 15). The intratracheal experiments used 42 hamsters in Experiment B plus additional cohorts of 15, and three groups of 60 hamsters each plus an untreated control group in Experiment C.
• Exposure: Three asbestos samples: harsh chrysotile Sample 1, soft chrysotile Sample 2 and amosite Sample 7. Experiment A gave a single intrapleural injection of 25 mg, with one per cent soft chrysotile or amosite added to the diet. Other experiments gave repeated weekly intratracheal injections, generally 0.5 to 2.5 mg per dose.
• Main results:
  • In the amosite group of 15 hamsters, pleural mesotheliomas were found at 244, 358 and 482 days after intrapleural injection.
  • In the harsh chrysotile group, pleural mesotheliomas were found at 419 and 527 days after injection. None were found in the soft chrysotile group. Each group had 15 hamsters given single 25 mg injections.
  • In the soft chrysotile group, one hamster had a sarcoma in a thick fibrous wall around an asbestos deposit in the axilla.
  • No tumors were found in the untreated control group of Experiment A.
  • Tumors found in the gastrointestinal tract and liver of hamsters fed asbestos may have been spontaneous growths unrelated to asbestos.
  • No respiratory tract tumors had been found in hamsters that had died so far in any of the groups given asbestos by intratracheal injection.
  • Lungs after intratracheal injection did not show thick fibrotic lesions like those seen after single massive intrapleural injections.
  • One small mesothelioma could be seen to have arisen in the thick fibrous wall of a pleural adhesion.
• The authors' conclusion: The authors concluded that asbestos can induce mesotheliomas in hamsters. They questioned whether the tumors reflect a primary cancer-causing action of asbestos fibers or are a secondary, nonspecific consequence of fibrosis.
• Limitations the authors state:
  • Injecting asbestos into the pleural cavity does not reproduce how people are exposed.
  • Many hamsters given intratracheal injections were still alive when the report was written, so the results by that route are incomplete.
  • For the four large pleural tumors, the exact point of origin could not be determined.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Amosite, Autopsy, Inflammation, Necrosis, Pleural Mesothelioma, Sarcoma, Mesothelioma.

Related studies

• Tests for effect of asbestos on benzo[a]pyrene carcinogenesis in the respiratory tract — L. Miller, W.E. Smith, et al. (1965)
• Interpretation of the carcinogenicity of amosite asbestos and ferroactinolite on the basis of retained fiber dose and characteristics in vivo — P.M. Cook, L.D. Palekar, et al. (1982)
• Experimental studies on asbestos carcinogenicity — L.M. Shabad, L.N. Pylev, et al. (1974)
• Asbestos-induced tumors in White Leghorn fowls — P.R. Peacock, A. Peacock (1965)
• Tumorigenesis by a ferroactinolite mineral — D.L. Coffin, L.D. Palekar, et al. (1982)
• Evaluation of the tumorigenic potential of vermiculite by intrapleural injection in rats — B. Hunter, C. Thomson (1973)

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