Pleural plaques, asbestos exposure, and asbestos bodies in bronchoalveolar lavage fluid

Our plain-English summary of Pleural plaques, asbestos exposure, and asbestos bodies in bronchoalveolar lavage fluid, by E. Orlowski, J.C. Pairon, J. Ameille, et al (American Journal of Industrial Medicine, 1994).

The study

• Authors: E. Orlowski, J.C. Pairon, J. Ameille, X. Janson, Y. Iwatsubo, G. Dufour, J. Bignon, P. Brochard
• Journal: American Journal of Industrial Medicine
• Published: 1994;26(3):349-58
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The profiles of occupational asbestos exposure were investigated in a series of 66 hospital patients in whom pleural plaques constituted the only asbestos-induced abnormality. The relationship between a radiological semiquantitative score of pleural plaques and indices of asbestos exposure was also examined. On the basis of a standardized occupational questionnaire, four classes of asbestos exposure were distinguished in our study population: no evidence of exposure, low-level exposure, sporadic exposure at higher levels, and a remaining group of individuals with substantial exposure. Asbestos body count in bronchoalveolar lavage fluid (BALF) was used as an objective indicator of cumulative lung retention of asbestos. Our results support the data indicating that pleural plaques may occur in subjects with low-level or sporadic asbestos exposure. Although it is admitted that pleural plaques are strongly associated with past asbestos exposure, our data suggest that the stage of pleural plaques was not correlated to the level, frequency, duration of exposure nor to the amount of asbestos bodies in the BALF in subjects free of any lung parenchymal abnormalities on high resolution computerized tomography.

In plain English

The authors studied a hospital-based series of 66 men in the Paris area, seen from 1987 to 1992, who had bilateral pleural plaques and no other radiological asbestos-related abnormality. A standardized job questionnaire placed each man in one of four exposure classes, and asbestos bodies were counted in fluid washed from the lungs (bronchoalveolar lavage). Of the 66, 57 had probable or definite occupational exposure. Of those 57, 12 had only low-level exposure and 10 had only sporadic exposure at higher levels. Overall, 47% had low-level, sporadic or no exposure. In the whole group, 39.4% had asbestos body counts at or above 1 per ml, the threshold the authors used for nontrivial exposure. Counts differed across the four exposure classes (p = 0.05). A radiological plaque score was correlated with age. It showed no relationship with exposure class, duration of exposure, smoking or asbestos body count. The authors concluded that plaques may occur with low-level or sporadic exposure and that plaque stage might not be related to exposure level and frequency. They noted that referral may have overrepresented heavily exposed people.

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: Hospital-based case series (cross-sectional study) of patients with bilateral pleural plaques and no other radiological asbestos-related abnormalities
• Who was studied: 66 males with pleural plaques, referred to two occupational medicine departments in the Paris area, 1987-1992. Patients with interstitial lung abnormalities on high-resolution CT, diffuse pleural thickening, or pleural, pulmonary, laryngeal or gastrointestinal cancers were excluded.
• Exposure: Occupational asbestos exposure assessed by a standardized questionnaire and grouped into four classes: no evidence of exposure, low-level exposure, sporadic exposure at higher levels, and substantial exposure. Asbestos body count in bronchoalveolar lavage fluid was used as an objective indicator of lung retention. No fiber types are named.
• Main results:
  • Of the 66 subjects with pleural plaques, 57 had a history of probable or definite asbestos exposure. Of these, 12 had only low-level exposure.
  • Among those exposed to at least medium levels of asbestos dust, 10 had only sporadic exposure.
  • Of the 66 patients, 47% had low-level or sporadic asbestos exposure or no exposure at all.
  • Whole sample: mean asbestos body count 36.9 per ml of lavage fluid (SD 166), median 0.5. The range was 0 to 1,250 per ml.
  • 14 of 66 subjects (21.2%) had no asbestos bodies identified in the lavage sample.
  • Whole sample: 39.4% had an asbestos body count at or above 1 per ml, the authors' threshold indicating nontrivial exposure. By class: class 0 (n = 9) 22.2%, class 1 (n = 12) 33.3%, class 2 (n = 10) 40.0%, class 3 (n = 35) 45.7%.
  • The proportion with counts at or above 1 per ml rose with exposure class, but a test for linear trend found no statistically significant association.
  • Asbestos body counts differed across the four exposure classes (p = 0.05), and class 3 differed significantly from class 0.
  • The pleural plaque score (range 1-17) was positively correlated with age (p less than 0.05). A positive correlation with time since first exposure was not statistically significant (r = 0.22, p = 0.095).
  • No relationship was found between the pleural plaque score and class of exposure, duration of exposure, cumulative smoking, or asbestos body concentration in lavage fluid. No significant association with asbestos body count was found within any exposure class either.
• The authors' conclusion: The authors concluded that their results add to data indicating that pleural plaques may occur with low-level or sporadic asbestos exposure. They also concluded that, where plaques occur without parenchymal abnormalities, plaque stage might not be related to level and frequency of exposure (nor, they added, to cumulative dose assessed by duration or asbestos body count).
• Limitations the authors state:
  • Subjects came from occupational medicine departments, so people with substantial asbestos exposure may have been overrepresented.
  • Excluding people with any parenchymal abnormality may have overrepresented people who develop plaques at low exposure and reduced the proportion with high plaque scores.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Asbestos Exposure, Asbestos Bodies, Bronchoalveolar Lavage (BAL), Asbestos Body Formation.

Related studies

• Pleural mesothelioma and exposure to asbestos: evaluation from work histories and analysis of asbestos bodies in bronchoalveolar lavage fluid or lung tissue in 131 patients — J.C. Pairon, E. Orlowski, et al. (1994)
• Diagnostic value of asbestos bodies in bronchoalveolar lavage fluid — P. De Vuyst, P. Dumortier, et al. (1987)
• Asbestos bodies in bronchoalveolar lavage fluids of brake lining and asbestos cement workers — P. Dumortier, P. De Vuyst, et al. (1990)
• Erionite bodies and fibres in bronchoalveolar lavage fluid (BALF) of residents from Tuzköy, Cappadocia, Turkey — P. Dumortier, L. Coplü, et al. (2001)
• Asbestos bodies in bronchoalveolar lavage fluid in relation to occupational history — A. Karjalainen, S. Anttila, et al. (1994)
• Fibres and asbestos bodies in bronchoalveolar lavage fluids of asbestos sprayers — T. Tuomi, P. Oksa, et al. (1992)

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