Laryngeal Lavage: A Potential Method of Evaluation of Amphibole Fiber Exposure

Our plain-English summary of Laryngeal Lavage: A Potential Method of Evaluation of Amphibole Fiber Exposure, by M. Germine, J.H. Puffer (Journal of Occupational and Environmental Medicine, 2019).

The study

• Authors: M. Germine, J.H. Puffer
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2019;61(6):525-528
• Read it: PubMed · Publisher

Abstract

Objective: Our objective is to propose a simple procedure for evaluating potential recent heavy exposure to tremolite.

Methods: One day after an accidental exposure to tremolite in rock dust, sputum was sampled; 3 months later a laryngeal lavage was taken. The sputum was examined with scanning electron microscopy (SEM); the lavage was examined with transmission electron microscopy (TEM).

Results: The sputum was found to contain abundant tremolite while the lavage contained very thin, high aspect-ratio fibers, many in the "Stanton Fiber" range. The abundance of tremolite from the larynx suggests accumulation. The thin fibers exhibit splitting from thicker fibers that were in the lungs.

Conclusions: Laryngeal lavage may be an important index of asbestos exposure and is a less complex and more diagnostic alternative to bronchoalveolar lavage or sputum sampling.

In plain English

This pilot study had one subject: the first author. While sampling tremolite asbestos at a serpentinite rock outcrop on Latrobe Road in El Dorado County, California, the author was accidentally exposed to dust. The next day the author coughed up green sputum. At 3 months and 10 months the author rinsed their own larynx (voice box) with about 40 mL of distilled water through a tube. Under the microscope, the sputum contained tremolite fibers about 2.0 micrometers wide. The 3-month rinse held tremolite fibers too numerous to count without dilution, averaging 14 fibers per grid square over three grid squares. The 25 fibers measured were much thinner, with a mean width of 0.21 micrometers. Four of the 25 met the Stanton criteria, which the authors describe as marking maximal potential to cause mesothelioma. No chrysotile was found. No asbestos fibers were detected in the 10-month rinse. The authors read the thin fibers as evidence that fibers split inside the body and built up temporarily in the larynx. They concluded that laryngeal lavage may be an important index of asbestos exposure and that further work is warranted.

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: Pilot study of a single person (the first author) using a self-performed procedure. The authors compared sputum and two laryngeal lavage samples taken at different times after one accidental exposure. The later lavage was used as a control.
• Who was studied: One person, the first author, a physician. The exposure happened during geological sampling at a serpentinite outcrop on Latrobe Road north of Latrobe, El Dorado County, California. No year is given.
• Exposure: A single accidental exposure to tremolite asbestos in rock dust from a serpentinite outcrop. It happened during field sampling in light wind and very dusty air. No airborne fiber levels were measured.
• Main results:
  • Sputum coughed up the day after exposure: 24 fibers were measured by polarized light microscopy. Their width was near or at 2.0 micrometers, their aspect ratio (length compared with width) ranged from 5:1 to 67:1, and their length ranged from 10 to 33.7 micrometers.
  • Laryngeal lavage at 3 months: three grid squares were examined by transmission electron microscopy at 10,000 times magnification. They averaged 14 tremolite fibers per grid square. No chrysotile was found.
  • In the 3-month lavage, 25 fibers were measured. Width ranged from 0.085 to 0.56 micrometers (mean 0.21), length from 0.6 to 19.00 micrometers (mean 6.4), and aspect ratio from 6.8:1 to 114:1 (mean 34:1).
  • Four of the 25 fibers measured in the 3-month lavage met the Stanton criteria, which the authors describe as the criteria for maximal potential to cause mesothelioma.
  • Laryngeal lavage at 10 months: no asbestos fibers were detected in three grid squares examined at 10,000 times magnification.
  • The authors interpreted the much thinner fibers in the lavage, compared with the outcrop fibers (mean width 2.0 micrometers), as evidence that fibers split inside the body.
• The authors' conclusion: The authors concluded that laryngeal lavage may be an important index of asbestos exposure and a less complex alternative to bronchoalveolar lavage or sputum sampling. They also concluded that tremolite fibers temporarily accumulated in the larynx and split inside the body. They called for further work to assess the procedure.
• Limitations the authors state:
  • The authors note that some laboratory work on this tremolite took place between the field work and the lavage. They say precautions were taken and that the exposure most likely occurred during the field work.
  • The authors suggest the thinner fibers may have come from road dust next to the outcrop, which was not sampled.
  • The authors acknowledge another explanation for the thin, short fibers: shorter fibers might simply collect in the larynx while longer fibers move on toward the lungs. They argue against this explanation.
  • The finding of no asbestos at 10 months applies only within the detection limits of the method, which examined three grid squares.

Topics

Medical terms in this study, explained in our Lexicon: Amphibole Group, Tremolite, Sputum, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Asbestos Exposure, Bronchoalveolar Lavage (BAL).

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