Environmental sample correlation with clinical and historical data in a friction product exposure

Our plain-English summary of Environmental sample correlation with clinical and historical data in a friction product exposure, by J.L. Levin, M. O'Sullivan, R.F. Dodson (Inhalation Toxicology, 2003).

The study

• Authors: J.L. Levin, M. O'Sullivan, R.F. Dodson
• Journal: Inhalation Toxicology
• Published: 2003;15(7):639-47
• Type of article: Case report
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos has been widely used in the past as a component in friction products. A unique setting of dust exposure to such products occurs when individuals are involved with refabrication of the worn components. It is of interest whether asbestos fibers are released from friction materials in the use phase and the postlife phase or if the mineral fibers are converted to a nonasbestos form. In the present study, an individual whose primary work activity had centered on clutch refabrication was evaluated for possible dust-related diseases. Tissue analysis revealed the presence of large numbers of asbestos fibers as well as ferruginous bodies. These particulates were characterized as to composition as well as dimensions. Clutches of the type typically used by this individual were obtained and material was rinsed from their surface for comparative purposes. Materials that were freed from the surface and reviewed by analytical transmission electron microscopy were clearly identifiable as chrysotile asbestos. The composition of the clutch material was compared with the components found in the patient's lung tissue. The conclusion from this comparison was that individuals exposed to friction materials under similar circumstances should use appropriate caution. Appreciable exposure to asbestos can occur and this exposure can be sufficiently high to result in disease.

In plain English

This case report described a 59-year-old man who had worked in a facility that reprocessed used clutches. His tasks included drilling connectors to separate components, and he had no other known occupational asbestos exposure. He had smoked one to one and a half packs of cigarettes a day for 35–40 years. He had diffuse interstitial fibrosis, scarring of the pleura at the top of both lungs, and severe restrictive lung disease. He was diagnosed with eosinophilic pneumonia with underlying asbestos-induced fibrosis, and later small-cell lung cancer. His lung tissue contained 3810 asbestos bodies per gram of dry tissue and more than 2 million uncoated chrysotile structures per gram. The authors rinsed eight used clutches reported as similar to those he worked on. The rinse held abundant chrysotile asbestos, with no detectable sign that the fibers had broken down or converted to another mineral. The authors concluded that after-use work with such friction materials may cause asbestos exposure sufficient to cause disease like his, including interstitial fibrosis and lung cancer.

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 of one worker, combining clinical history, lung tissue fiber analysis, and electron microscopy of material rinsed from used clutches
• Who was studied: One 59-year-old man evaluated at the authors' facility (University of Texas Health Center at Tyler) with shortness of breath and persistent cough. He had smoked one to one and a half packs per day for 35–40 years. Dates of evaluation were not given.
• Exposure: Work in a facility that reprocessed (refabricated) used clutches, including drilling connectors to separate components. The authors reported no other known occupational asbestos exposure. Material rinsed from clutches reported as similar to those repaired was chrysotile asbestos.
• Main results:
  • In the patient, clinical evaluation found diffuse interstitial fibrosis at the lung bases and bilateral apical pleural scarring.
  • The patient was diagnosed with eosinophilic pneumonia with underlying asbestos-induced fibrosis.
  • At a later admission, a biopsy showed that a right hilar mass in the patient's lung was small-cell undifferentiated carcinoma.
  • Material rinsed from eight used clutches contained chrysotile asbestos as bundles, fibrils or clusters, with up to 1000 fibers per grid opening.
  • Of the clutch fibers, 93% were less than 0.1 µm in diameter. Ninety percent were less than 8 µm long and 75% were less than 5 µm long.
  • No degradation or conversion of the clutch fibers to another mineral form was detected.
  • The patient's lung tissue contained 3810 asbestos bodies per gram of dry tissue, and their cores were identified as chrysotile.
  • In a continuous count of 33 fibers in the patient's lung tissue, 30 were chrysotile, with an average length of 12.95 µm and an average diameter of 0.063 µm. The other three were one anthophyllite fiber, one magnesium aluminum ferrosilicate fiber and one titanium fiber.
  • The patient's uncoated chrysotile burden was greater than 2 million chrysotile structures (fibrils and bundles combined) per gram of dry lung tissue.
  • For comparison, the authors cited their own earlier studies of non-occupationally exposed East Texas residents (not this study), in which ferruginous body burdens ranged from 0 to 200 per gram of dry lung tissue.
• The authors' conclusion: The authors concluded that chrysotile from the clutch faces was strikingly similar to that in the worker's lung. They wrote that work with such friction materials in the after-use phase may produce appreciable asbestos exposure, sufficient to cause disease of the type seen in this case, including interstitial fibrosis and lung cancer.

Topics

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

Medical terms in this study, explained in our Lexicon: Friction Products, Mineral Fiber, Ferruginous Bodies, Analytical Transmission Electron Microscopy (ATEM), Chrysotile.

Related studies

• History and evolution of warning labels for automotive friction products — L.M. Kopelovich, K.A. Thuett, et al. (2014)
• Relation of occupational exposure to respiratory symptoms and asthma in a general population sample: self-reported versus interview-based exposure data — P.S. Bakke, R. Hanoa, et al. (2001)
• Environmental history of a factory producing friction material — J.W. Skidmore, B.L. Dufficy (1983)
• Fibrous dust release from asbestos substitutes in friction products — S.A. Jaffrey, A.P. Rood, et al. (1992)
• Potential artifacts associated with historical preparation of joint compound samples and reported airborne asbestos concentrations — G.P. Brorby, P.J. Sheehan, et al. (2011)
• Relationships between simultaneous airborne dust samples taken with five types of instruments at South African asbestos mines and mills — R.S. Du Toit, L.W. Isserow, et al. (1983)

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