Tumor incidence was not related to the thickness of visceral pleural in female Syrian hamsters intratracheally administered amphibole asbestos or manmade fibers

Our plain-English summary of Tumor incidence was not related to the thickness of visceral pleural in female Syrian hamsters intratracheally administered amphibole asbestos or manmade fibers, by S. Adachi, K. Kawamura, K. Kimura, et al (Environmental Research, 1992).

The study

• Authors: S. Adachi, K. Kawamura, K. Kimura, K. Takemoto
• Journal: Environmental Research
• Published: 1992;58(1):55-65
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Histological observations were performed on female Syrian hamsters 2 years after the intratracheal administration of amphibole asbestos, amosite, and crocidolite to evaluate the tumorigenicity of six types of fine manmade fibers (reported previously). A mesothelioma and a lung tumor were induced in 20 animals administered amosite, but no tumors were found in the crocidolite group. Because this incidence is not higher than that of manmade fibers, such as basic magnesium sulfate fiber [9 tumor-bearing hamsters in 20 hamsters (9/20)], metaphosphate fiber (5/20), calcium sulfate fiber (3/20), and fiberglass (2/20), it is suggested that some types of manmade fibers have a greater ability than asbestos to induce tumors. Moreover, as a specific observation in manmade fiber groups, tumors were induced at intracelial organs rather than at the pleural cavity. On the other hand, the average thickness of visceral pleura was higher in all asbestos and manmade fiber groups than in the control (2.9 microns), for instance, 36.95 microns in potassium titanate fiber group, 15.90 microns crocidolite group, 13.00 microns basic magnesium sulfate fiber group, and 10.45 microns in the rockwool group. Although both pleural thickening and mesothelioma are known as peculiar lesions in asbestos-exposed people, it might also be suggested that these lesions could be induced by different mechanisms from the result that there was no relation between the pleural thickening and mesothelioma incidence in hamsters.

In plain English

This was an animal experiment from Japan. Groups of 20 female Syrian hamsters had suspensions of amosite or crocidolite (two types of amphibole asbestos), or of one of several manmade fibers, injected into the windpipe once a week for 5 weeks, a total dose of 10.0 mg per animal. A control group received the liquid alone. Tumor results for the manmade fibers included data from the authors' earlier paper. After 2 years, 2 of 20 hamsters given amosite had tumors (one pleural mesothelioma, one lung adenoma), and none of 20 given crocidolite did. In the manmade fiber groups, 0/20 to 9/20 hamsters had tumors, the most with basic magnesium sulfate fiber. Many of these tumors were in internal organs rather than the pleural cavity. All fiber groups had thicker visceral pleura (the lining of the lung) than controls. The thickest was the potassium titanate fiber group, which had no tumors. No lesions like pleural plaques were seen. The authors suggested some manmade fibers should be considered possible carcinogens. They concluded that pleural thickening and mesothelioma might arise independently.

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 (intratracheal administration of fibers to hamsters, with histological examination after 2 years)
• Who was studied: Female Syrian hamsters (80 g, from Shizuoka, Japan), in groups of 20 per fiber type plus a control group of 20 given vehicle only
• Exposure: Amosite and crocidolite (amphibole asbestos), compared with manmade fibers: basic magnesium sulfate, calcium sulfate, carbon fiber, fiberglass, metaphosphate, potassium titanate and rockwool. Each was given as a saline suspension (0.2 ml per animal) into the trachea once a week for 5 weeks, a total dose of 10.0 mg per animal. Controls received vehicle alone.
• Main results:
  • Amosite group: 2 of 20 hamsters had tumors (one epithelial-type pleural mesothelioma, one lung adenoma). Crocidolite group: 0 of 20.
  • No tumors were found in the crocidolite, carbon fiber, potassium titanate fiber or vehicle control groups.
  • Tumor-bearing hamsters in the manmade fiber groups (counts of hamsters, not of tumors; some hamsters had more than one tumor): fiberglass 2, calcium sulfate 3, metaphosphate 5 and basic magnesium sulfate 9, each out of 20. Overall the range was 0/20 to 9/20.
  • In the manmade fiber groups, tumors arose in internal organs (described as intracelial organs) rather than in the pleural cavity.
  • Thickening was seen in the visceral pleura, not the parietal pleura or diaphragm. No lesion like a pleural plaque was detected.
  • Mean visceral pleural thickness was higher in all asbestos and manmade fiber groups than in controls. Controls averaged 2.90 micrometres. The fiber groups averaged: potassium titanate 36.95, crocidolite 15.90, basic magnesium sulfate 13.00, rockwool 10.45 and amosite 5.60.
  • The potassium titanate group had the thickest visceral pleura (mean 36.95 micrometres) but no tumors.
• The authors' conclusion: The authors suggested that several types of manmade fibers should be considered possible carcinogens. Because the fibers that produced mesothelioma did not cause severe pleural thickening, and potassium titanate caused thickening but no tumors, the authors concluded that pleural thickening and mesothelioma might be induced independently.

Topics

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

Medical terms in this study, explained in our Lexicon: Amphibole Asbestos, Amosite, Crocidolite, Mesothelioma, Pleural Cavity, Visceral Pleura, Pleural Thickening.

Related studies

• Mineral fibers induce apoptosis in Syrian hamster embryo fibroblasts — E. Dopp, B. Nebe, et al. (1995)
• Studies on the inhalation toxicology of two fiberglasses and amosite asbestos in the Syrian golden hamster. Part II. Results of chronic exposure — E.E. McConnell, C. Axten, et al. (1999)
• Studies on the inhalation toxicology of two fiberglasses and amosite asbestos in the syrian golden hamster. Part I. Results of a subchronic study and dose selection for a chronic study — T.W. Hesterberg, C. Axten, et al. (1999)
• In vitro cytotoxicity and transforming potential of industrial carbon dust (fibers and particles) in syrian hamster embryo (SHE) cells — C. Darne, F. Terzetti, et al. (2010)
• 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)
• Chronic inhalation study of fiber glass and amosite asbestos in hamsters: twelve-month preliminary results — T.W. Hesterberg, C. Axten, et al. (1997)

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