Pleural plaques in dentists from occupational asbestos exposure: a report of three cases

Our plain-English summary of Pleural plaques in dentists from occupational asbestos exposure: a report of three cases, by L. Sichletidis, D. Spyratos, D. Chloros, et al (American Journal of Industrial Medicine, 2009).

The study

• Authors: L. Sichletidis, D. Spyratos, D. Chloros, K. Michailidis, I. Fourkiotou
• Journal: American Journal of Industrial Medicine
• Published: 2009;52(12):926-30
• Type of article: Case report
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: White asbestos (chrysotile) has been used in dentistry since 1930 when it was introduced as a lining material for casting rings.

Methods: All three patients presented with pleural plaques on chest X-rays as well as on CT-scans. They were working as dentists for 35-45 years. Under the instructions of the first dentist we represented precisely the whole process of manipulating a kind of paper that contained asbestos. In order to measure asbestos fibers concentration we used the membrane filter method and phase contrast optical microscopy. Dry asbestos sheets were scanned with x-ray diffraction and electron microscope.

Results: Analysis of the filter demonstrated 0.008 fibers/cm(3) during the sampling period. X-ray diffraction analysis revealed that the material consisted of chrysotile exclusively. Electron microscope pictures confirmed the presence of chrysotile.

Conclusion: Everyday occupational exposure for many years even to low asbestos levels, under poor ventilation conditions in a closed space, could cause pleural lesions.

Copyright 2009 Wiley-Liss, Inc.

In plain English

This case report described three male dentists, aged 68, 74 and 80 when examined between 2005 and 2008, who had worked as dentists for 35 to 45 years. All three had used paper or tape containing asbestos, soaked in water, to shape molds for casting gold. Chest X-rays and CT scans showed pleural changes that the authors described as plaques compatible with asbestos exposure. In the third dentist, who had never smoked, plaques were also seen on the pericardium. The second dentist, a heavy smoker, also had a lung mass that proved to be squamous cell carcinoma. The authors reported that the plaques did not affect the patients' breathing function. To estimate exposure, the authors re-created the casting process for 4 hours in a small room without windows or ventilation. Air sampling measured 0.008 fibers per cubic centimeter, and analysis showed the material was chrysotile only. The authors concluded that everyday exposure for many years, even to low asbestos levels, in a poorly ventilated closed space could cause pleural lesions. They noted that real fiber levels in the dentists' laboratories may have been higher than in their 4-hour experiment.

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 three patients, with a simulation of the work process (air sampling) and a mineral analysis of the casting material
• Who was studied: Three male dentists, aged 80, 74 and 68, examined in 2008, 2005 and 2007 respectively, who had worked as dentists for 35 to 45 years. The authors are based at Aristotle University of Thessaloniki, Greece.
• Exposure: Paper or dental tape containing asbestos, wetted and shaped into fire-resistant molds in which gold was melted during casting. The mineral analysis found chrysotile only. The dentists' laboratories had no windows or ventilation, and the dentists worked in them about 4 hours a day.
• Main results:
  • Patient 1 (80 years old, former smoker of 30 pack-years): the chest X-ray showed pleural thickening, and the CT scan showed lesions compatible with pleural plaques due to asbestos exposure.
  • Patient 2 (74 years old, current smoker of 80 pack-years): the chest X-ray showed bilateral pleural calcifications and the CT scan showed characteristic pleural plaques. A lung mass proved to be squamous cell carcinoma.
  • Patient 3 (68 years old, never smoked): the CT scan showed characteristic pleural and pericardial plaques compatible with asbestos exposure.
  • Simulation: no asbestos fibers were found in the room before the experiment. During the 4-hour simulation of the casting process, the airborne concentration was 0.008 fibers per cubic centimeter.
  • X-ray diffraction showed that the casting material was chrysotile only, and electron microscope images confirmed that it was asbestiform.
  • The plaques did not affect the patients' respiratory function. The authors attributed the obstructive lung function defect in patients 1 and 2 to their long smoking histories.
• The authors' conclusion: The authors concluded that everyday occupational exposure for many years, even to low asbestos levels, under poor ventilation in a closed space could cause pleural lesions. They also wrote that the low measured fiber level suggested these dentists should not have had a significant risk for asbestosis, and that asbestos-related disease should be considered as a possibility in elderly dentists.
• Limitations the authors state:
  • Actual fiber concentrations in the dentists' small enclosed laboratories may have been higher than those measured in the 4-hour experiment.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Asbestos Exposure, Chrysotile, Chest X-Ray, Membrane Filter Method, X-Ray Diffraction (XRD), Occupational Exposure.

Related studies

• Safeguarding the physical well-being of dentists — M. Wagner (1985)
• CT Characteristics of Pleural Plaques Related to Occupational or Environmental Asbestos Exposure from South Korean Asbestos Mines — Y. Kim, J.P. Myong, et al. (2015)
• Mortality from occupational exposure to relatively pure chrysotile: a 39-year study — L. Sichletidis, D. Chloros, et al. (2009)
• Inter-reader agreement in HRCT detection of pleural plaques and asbestosis in participants with previous occupational exposure to asbestos — F. Laurent, C. Paris, et al. (2014)
• Diachronic study of pleural plaques in rural population with environmental exposure to asbestos — L. Sichletidis, D. Chloros, et al. (2006)
• Chest imaging and lung function impairment after long-term occupational exposure to low concentrations of chrysotile — D. Spyratos, D. Chloros, et al. (2012)

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