Environmental exposure to Libby Asbestos and mesotheliomas

Our plain-English summary of Environmental exposure to Libby Asbestos and mesotheliomas, by A.C. Whitehouse, C.B. Black, M.S. Heppe, et al (American Journal of Industrial Medicine, 2008).

The study

• Authors: A.C. Whitehouse, C.B. Black, M.S. Heppe, J. Ruckdeschel, S.M. Levin
• Journal: American Journal of Industrial Medicine
• Published: 2008;51(11):877-80
• Type of article: Case report
• Cited by: 68 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Thirty-one cases of mesothelioma resulting from exposure to Libby Asbestos have been identified from Libby, Montana. Eleven cases not previously reported are the subject of this report.

Methods: These cases are in non-occupationally exposed people, appearing to have resulted from exposure to contamination of the community, the surrounding forested area, and areas in proximity to the Kootenai river and railroad tracks used to haul vermiculite.

Results: These exposures are considered to be of a low degree of magnitude, but are similar to those in Western Australia's crocidolite mine at Wittenoom Gorge. An epidemic of mesothelioma can likely be expected from this type of asbestos contamination over the next 20 plus years.

Copyright 2008 Wiley-Liss, Inc.

In plain English

This brief report described 11 people with mesothelioma whose exposure the authors linked to Libby, Montana. In Libby, the ore of a vermiculite mine was contaminated with amphibole asbestos. None of the 11 were mine workers. Two were family members of workers, and nine were exposed through the community and surrounding area. The Center for Asbestos Related Disease in Libby had learned of the cases since 1995. All were pleural mesothelioma except one peritoneal case. The time from first known Libby exposure ranged from 13 to 67 years, and the youngest patient was 48 at diagnosis. Some patients also had possible asbestos exposure elsewhere, such as construction or carpentry work. In 1975 the mining company measured 1.1 fibers per milliliter of air at the downtown hospital and 1.5 near the lumber mill and railyards. The authors judged these levels similar to those in the town of Wittenoom, Australia. The authors stated that the cases exceeded the number expected and that their count is probably an underestimate. They concluded the epidemic would probably not peak for another 10 to 20 years.

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: Brief report: case series of 11 mesothelioma cases
• Who was studied: 11 people with malignant mesothelioma known to the Center for Asbestos Related Disease (CARD) in Libby, Montana, since 1995: two family members of W.R. Grace workers and nine people with environmental exposure only. Four further cases in W.R. Grace employees were not reported.
• Exposure: Non-occupational exposure to Libby Asbestos from contamination of the community, the surrounding forest, and areas near the Kootenai River and the railroad tracks used to haul vermiculite. The vermiculite ore contained amphibole asbestos.
• Main results:
  • 10 of the 11 cases were pleural mesothelioma; Case 2 was peritoneal mesothelioma.
  • Across the 11 cases, latency from first known exposure to asbestos in Libby ranged from 13 to 67 years.
  • The youngest patient in the series was 48 at diagnosis.
  • Some patients had possible asbestos exposure outside Libby. Case 1 had worked in construction, and Case 5 was a lifelong carpenter.
  • The wife of Case 3 had asbestos-related pleural disease after residential exposure only.
  • Measured in 1975 by W.R. Grace: 1.1 fibers/ml at the downtown Libby hospital and 1.5 fibers/ml near the lumber mill and railyards. The authors considered these levels similar on the surface to those in the town of Wittenoom.
  • The authors stated that the 11 cases (9 environmental, 2 household) exceeded the number expected for Central Lincoln County, population 9,521. They did not report a calculated rate.
• The authors' conclusion: The authors concluded that the latency period for environmental mesothelioma from Libby exposures is far from complete, and that the epidemic will probably not peak for another 10 to 20 years.
• Limitations the authors state:
  • The case count is probably an underestimate. Dam workers, transient lumber mill workers and people who left Libby could not be followed.
  • Apart from the use of phase contrast microscopy, nothing is known about how the 1975 air measurements were made.
  • Biopsy pathology reports were not obtained for one case.
  • The exposure history for Case 5 came only from his widow.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Libby vermiculite mine, Montana

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Environmental Exposure, Mesothelioma, vermiculite, Crocidolite, Wittenoom.

Related studies

• Lung cancer screening in patients with Libby amphibole disease: High yield despite predominantly environmental and household exposure — G. Loewen, B. Black, et al. (2019)
• Social Support Functions During a Slowly-Evolving Environmental Disaster: The Case of Amphibole Asbestos Exposure in Libby, Montana — R.J. Cline, H. Orom, et al. (2015)
• Determining satisfaction with access and financial aspects of care for persons exposed to Libby amphibole asbestos: rural and national environmental policy implications — C.A. Winters, W. Hill, et al. (2011)
• Rapid progression of pleural disease due to exposure to Libby amphibole: "Not your grandfather's asbestos related disease" — B. Black, J. Szeinuk, et al. (2014)
• Community-level social support responses in a slow-motion technological disaster: the case of Libby, Montana — R.J. Cline, H. Orom, et al. (2010)
• Lung function, radiological changes and exposure: analysis of ATSDR data from Libby, MT, USA — D. Weill, G. Dhillon, et al. (2011)

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