Malignant mesothelioma induced in baboons by inhalation of amosite asbestos

Our plain-English summary of Malignant mesothelioma induced in baboons by inhalation of amosite asbestos, by I. Webster, B. Goldstein, F.S. Coetzee, et al (American Journal of Industrial Medicine, 1993).

The study

• Authors: I. Webster, B. Goldstein, F.S. Coetzee, G.C. van Sittert
• Journal: American Journal of Industrial Medicine
• Published: 1993;24(6):659-66
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Ten out of 12 South African baboons (Papio ursinus) survived exposure to amosite asbestos dust for periods ranging from 242 days to 898 days at an aerosol level ranging between 1,100 and 1,200 fibers per milliliter. After exposure, they were kept under observation until they died; the total residence time of amosite varied from 1.2-10.2 years. All underwent detailed postmortem necropsy examinations. All baboons had asbestosis. Five of the baboons developed malignant diffuse mesothelioma; three peritoneal, and two pleural with peritoneal invasion. These results indicate that amosite is highly carcinogenic. Since it is difficult to accomplish follow-up of persons exposed to amosite asbestos because of the geographic location of the amosite mines and mills in South Africa (a majority of the workers being migrant laborers from countries bordering on the Transvaal), it is therefore probable that cases of peritoneal mesothelioma have been missed. If human beings are likely to react to amosite as do baboons, epidemiological follow-up should include identification of abdominal as well as thoracic neoplasms.

In plain English

In this animal experiment, begun in South Africa in September 1980, the authors exposed 12 male baboons (Papio ursinus) to airborne amosite asbestos in an inhalation chamber. The baboons came from areas far from asbestos industry. Fiber levels were 1,100 to 1,200 fibers per milliliter, 6 hours a day, 5 days a week, for 242 to 898 days. Afterward they were allowed their natural life span, except when animals with mesothelioma needed relief from suffering; the reported total residence time of amosite was 1.2 to 10.2 years. By November 1992, 10 had died and been examined after death; two were still alive. All the baboons had asbestosis, of varying severity. Five of the 10 dead baboons had malignant mesothelioma. Three were peritoneal (abdominal lining), and two were pleural (chest lining) with spread to the peritoneum. Under the microscope, the tumors resembled the epithelial type of human mesothelioma. The authors concluded that amosite is highly carcinogenic at the exposure levels used. They suggested that some mesotheliomas in amosite-exposed workers may have been missed because some tumors appear in the abdomen.

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 inhalation experiment (no comparison group described)
• Who was studied: 12 male South African baboons (Papio ursinus) from parts of South Africa remote from asbestos industry or mineral deposits; exposure commenced September 1980; status reported as of November 1992
• Exposure: inhaled amosite asbestos (prepared for the UICC samples) at 1,100 to 1,200 fibers per milliliter, 6 hours daily, 5 days per week, for 242 to 898 days; total residence time of amosite 1.2 to 10.2 years
• Main results:
  • Ten of the 12 baboons had died at the time of reporting; two were still alive in November 1992
  • All the baboons had asbestosis, of differing severity
  • Three of the 10 deceased baboons developed diffuse malignant peritoneal mesothelioma
  • Two further baboons had pleural mesothelioma that had spread to the peritoneum: baboon no. 7, with tumor mainly of the diaphragm, and one other with diffuse pleural mesothelioma
  • The tumors were histologically similar to the epithelial type of mesothelioma found in humans
• The authors' conclusion: The authors concluded that amosite is highly carcinogenic at the exposure levels used in the experiment. They suggested that some mesotheliomas in amosite-exposed workers may have been missed because some tumors present in the abdomen, and called for epidemiological inquiry among amosite workers in neighboring countries.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Amosite, Autopsy, Carcinogenic, Transvaal, Peritoneal Mesothelioma, Neoplasm.

Related studies

• Characterization of asbestos fibers in lungs and mesotheliomatous tissues of baboons following long-term inhalation — K. Hiroshima, Y. Murai, et al. (1993)
• The effects of asbestos-cement dust inhalation on baboons — B. Goldstein, I. Webster, et al. (1978)
• 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)
• Quantification of the pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite-asbestos following short-term inhalation exposure — D.M. Bernstein, R.A. Rogers, et al. (2011)
• The pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite asbestos following short-term inhalation exposure: interim results — D.M. Bernstein, R.A. Rogers, et al. (2010)
• 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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