Railroad workers with pleural plaques: II. Small airway dysfunction among asbestos-exposed workers

Our plain-English summary of Railroad workers with pleural plaques: II. Small airway dysfunction among asbestos-exposed workers, by U. Hjortsberg, P. Orbaek, M. Aborelius, et al (American Journal of Industrial Medicine, 1988).

The study

• Authors: U. Hjortsberg, P. Orbaek, M. Aborelius, J. Ranstam, H. Welinder
• Journal: American Journal of Industrial Medicine
• Published: 1988;14(6):643-7
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002001).

Abstract

Increased volume of trapped gas (VTG) was found in 87 asbestos-exposed railroad repair shop workers, divided into three subgroups according to smoking habits. All the examined subjects had pleural plaques. Determination of VTG was used to study function of small airways. Increased VTG was found among asbestos-exposed smokers as well as nonsmokers. In both groups the VTG:TLC ratio was elevated compared with controls. Increased VTG is a sign of small airways dysfunction. In asbestos-exposed subjects, it might be caused by an early peribronchial reaction to inhaled asbestos fibers.

In plain English

This Swedish study, Part II of a two-part report, measured the volume of trapped gas (VTG) in 87 men aged 39 to 78. The authors used this breathing test to assess the small airways. The men had been exposed to asbestos, mainly chrysotile and to some extent crocidolite, while renovating train cars in a railroad repair shop, and all had pleural plaques. Their results were compared with expected values from healthy nonsmoking men examined at the authors' laboratory. For the whole group, average VTG was 167 ml, against a reference mean of 102 ml. VTG as a share of total lung capacity was also raised. Raised values were found among smokers, ex-smokers and the 22 never smokers. The increases were linked to how much the men had smoked, but not to how long they had been exposed to asbestos. The authors suggested that the raised VTG indicates structural changes in the small airways, such as peribronchial fibrosis. They said it remains to be shown whether these workers will go on to develop more pronounced restrictive lung disease.

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: Cross-sectional lung function study of asbestos-exposed workers with pleural plaques, compared with predicted values from a laboratory reference group of healthy nonsmoking men
• Who was studied: 87 men aged 39-78 years (median 57), all with pleural plaques, who had worked in a railroad repair shop for train cars (Malmö, Sweden). They were divided into 27 ex-smokers, 38 smokers and 22 never smokers. Comparison was with a laboratory reference group of 200 healthy nonsmoking men aged 20-70; reference values for VTG came from 62 of them.
• Exposure: Asbestos exposure while renovating train cars, mainly chrysotile and to some extent crocidolite, with total exposure time of 6-46 years (median 30). Smoking was measured by a smoking index (cigarettes per day multiplied by years of smoking).
• Main results:
  • In the whole group (n = 87), VTG and the VTG:TLC ratio were increased compared with the reference group. Mean VTG was 167 ml (SD 72) and mean VTG:TLC was 2.6% (SD 1.1), both p less than 0.001 against expected values. The reference VTG mean was 102 ml (SD 21.2).
  • Increased VTG:TLC was found in the smokers (n = 38; mean VTG 192 ml, VTG:TLC 2.9%), in the ex-smokers (n = 27; mean VTG 164 ml, VTG:TLC 2.7%) and in the never smokers (n = 22; mean VTG 133 ml, SD 49; VTG:TLC 2.0%, SD 0.8).
  • Washout volume (WOV) was somewhat increased for the whole group, mainly because of the smokers. Smokers' mean WOV was 36.0 liters (SD 11.7, p less than 0.01).
  • In multiple regression, increases in WOV, VTG and VTG:TLC depended on the smoking index.
  • No dependency was found between these measurements and asbestos exposure time, earlier lung disease, or X-ray abnormalities not related to asbestos.
• The authors' conclusion: The authors suggested that the increased VTG indicates structural changes in the small airways, such as peribronchial fibrosis, which conventional spirometry does not detect. In their summary they wrote that, in asbestos-exposed subjects, it might be caused by an early peribronchial reaction to inhaled asbestos fibers.
• Limitations the authors state:
  • The authors stated that it has not yet been shown whether workers with this small airway dysfunction will develop more pronounced restrictive lung disease.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening, Railroads.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Habit.

Related studies

• Railroad workers with pleural plaques: I. Spirometric and nitrogen washout investigation on smoking and nonsmoking asbestos-exposed workers — U. Hjortsberg, P. Orbaek, et al. (1988)
• Asbestos-related pleural plaques and lung function — L.C. Oliver, E.A. Eisen, et al. (1988)
• Asbestos-related disease in railroad workers. A cross-sectional study — L.C. Oliver, E.A. Eisen, et al. (1985)
• A case-control study of lung cancer and diesel exhaust exposure in railroad workers — E. Garshick, M.B. Schenker, et al. (1987)
• Roentgenographic evidence of asbestos exposure in a select population of railroad workers — M.J. Sepulveda, J.A. Merchant (1983)
• Railways and asbestos in Japan (1928-1987)--epidemiology of pleural plaques, malignancies and pneumoconioses- — Y. Hosoda, Y. Hiraga, et al. (2008)

Browse more research in American Journal of Industrial Medicine, or return to medical research.