Fatal asbestosis 50 years after brief high intensity exposure in a vermiculite expansion plant

Our plain-English summary of Fatal asbestosis 50 years after brief high intensity exposure in a vermiculite expansion plant, by R.S. Wright, J.L. Abraham, P. Harber, et al (American Journal of Respiratory and Critical Care Medicine, 2002).

The study

• Authors: R.S. Wright, J.L. Abraham, P. Harber, B.R. Burnett, P. Morris, P. West
• Journal: American Journal of Respiratory and Critical Care Medicine
• Published: 2002;165(8):1145-9
• Type of article: Case report
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The authors report the case of a 65-year-old accountant whose only asbestos exposure was during a summer job 50 years earlier in a California vermiculite expansion plant. Vermiculite is a silicate material that is useful in building and agriculture as a filler and insulating agent. He developed extensive fibrocalcific pleural plaques and end-stage pulmonary fibrosis, with rapidly progressive respiratory failure. Careful occupational and environmental history revealed no other source of asbestos exposure, and the initial clinical diagnosis was idiopathic pulmonary fibrosis; open lung biopsy shortly before his death confirmed asbestosis. Electron microscopic lung fiber burden analysis revealed over 8,000,000 asbestos fibers per gram dry lung, 68% of which were tremolite asbestos. Additional asbestiform fibers of composition not matching any of the standard asbestos varieties were also present at over 5,000,000 fibers per gram dry lung. Comparison analysis of a sample of Libby, Montana, vermiculite showed a similar mix of asbestiform fibers including tremolite asbestos. This case analysis raises several concerns: risks of vermiculite induced disease among former workers of the more than 200 expansion plants throughout the United States; health effects of brief but very high-intensity exposures to asbestos; and possible health effects in end-users of consumer products containing vermiculite.

In plain English

This case report described one man, a 65-year-old accountant. The only asbestos exposure the authors identified was summer work in 1951 and 1952, at ages 18 and 19, at a Southern California vermiculite expansion plant that received ore from Libby, Montana. Chest X-rays had shown extensive pleural fibrocalcific disease from age 50. Doctors first considered idiopathic pulmonary fibrosis, but an open lung biopsy found fibrosis with easily found asbestos bodies, which confirmed asbestosis. He later died of respiratory failure at home, and no autopsy was done. His lung tissue contained 178,000 asbestos bodies and 14.5 million asbestiform fibers per gram of dry lung. These included 5.94 million tremolite fibers and 5.75 million 'other' asbestiform fibers. No amosite or crocidolite was detected. A sample of Libby vermiculite showed fiber compositions remarkably similar to those in his lung. The authors noted he may have had some asbestos exposure in the Navy but judged it very unlikely to have caused asbestosis. They concluded his disease was related to his vermiculite work and that former expansion plant workers should be considered at risk.

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: case report (one patient), with lung fiber analysis and comparison to a Libby vermiculite sample
• Who was studied: one 65-year-old accountant in California whose only identified asbestos exposure was summer work in a vermiculite expansion plant 50 years earlier
• Exposure: two consecutive summers (1951 to 1952, ages 18 and 19) at a Southern California expansion plant handling vermiculite ore from Libby, Montana: unloading ore, operating a forklift, shoveling ore into bags and sometimes into ovens
• Main results:
  • At age 50, a routine chest radiograph of the patient showed extensive pleural fibrocalcific disease on both sides
  • Idiopathic pulmonary fibrosis was considered, but the lung biopsy showed asbestos bodies, which confirmed asbestosis
  • The patient died of hypercapnic respiratory failure at home, and no autopsy was performed
  • The patient's lung contained 178,000 asbestos bodies per gram dry lung
  • Asbestiform fibers in the patient's lung totaled 14.5 million per gram dry lung
  • In the lung, fibers per gram dry lung were: tremolite 5.94 million, actinolite 1.78 million, chrysotile 0.99 million, anthophyllite 0.05 million
  • The lung also held 5.75 million 'other' asbestiform fibers per gram dry lung, described as sodium-calcium magnesium silicates characteristic of Libby vermiculite
  • No amosite or crocidolite fibers were detected in the patient's lung
  • Fibers in the patient's lung and in a Libby vermiculite sample showed similar ranges of composition
• The authors' conclusion: The authors concluded that the patient's lung disease was related to his vermiculite work, and that workers from former vermiculite expansion plants and other industries packaging or using vermiculite should be considered at risk
• Limitations the authors state:
  • The authors acknowledged possible asbestos exposure during Navy service (e.g., sleeping below decks) but judged it very unlikely to have been enough to cause asbestosis

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: Asbestosis, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: vermiculite, Asbestos Exposure, Silicate, Pleural Plaques, Pulmonary Fibrosis, Idiopathic, Biopsy, Fiber Burden Analysis.

Related studies

• Risk assessment using exposure intensity: an application to vermiculite mining — P.M. Vacek, J.C. McDonald (1991)
• Low-level fiber-induced radiographic changes caused by Libby vermiculite: a 25-year follow-up study — A.M. Rohs, J.E. Lockey, et al. (2008)
• The morbidity and mortality of vermiculite miners and millers exposed to tremolite-actinolite: Part III. Radiographic findings — H.E. Amandus, R. Althouse, et al. (1987)
• Pulmonary changes after exposure to vermiculite contaminated with fibrous tremolite — J.E. Lockey, S.M. Brooks, et al. (1984)
• Radiographic evidence of nonoccupational asbestos exposure from processing Libby vermiculite in Minneapolis, Minnesota — B.H. Alexander, K.K. Raleigh, et al. (2012)
• Asbestos-related radiographic findings among household contacts of workers exposed to Libby vermiculite: impact of workers' personal hygiene practices — T.J. Hilbert, A. Franzblau, et al. (2013)

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