CT Characteristics of Pleural Plaques Related to Occupational or Environmental Asbestos Exposure from South Korean Asbestos Mines

Our plain-English summary of CT Characteristics of Pleural Plaques Related to Occupational or Environmental Asbestos Exposure from South Korean Asbestos Mines, by Y. Kim, J.P. Myong, J.K. Lee, et al (Korean Journal of Radiology, 2015).

The study

• Authors: Y. Kim, J.P. Myong, J.K. Lee, J.S. Kim, Y.K. Kim, S.H. Jung
• Journal: Korean Journal of Radiology
• Published: 2015;16(5):1142-52
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: This study evaluated the CT characteristics of pleural plaques in asbestos-exposed individuals and compared occupational versus environmental exposure groups.

Materials And Methods: This study enrolled 181 subjects with occupational exposure and 98 with environmental exposure from chrysotile asbestos mines, who had pleural plaques confirmed by a chest CT. The CT scans were analyzed for morphological characteristics, the number and distribution of pleural plaques and combined pulmonary fibrosis. Furthermore, the CT findings were compared between the occupational and environmental exposure groups.

Results: Concerning the 279 subjects, the pleural plaques were single in 2.2% and unilateral in 3.6%, and showed variable widths (range, 1-20 mm; mean, 5.4 ± 2.7 mm) and lengths (5-310 mm; 72.6 ± 54.8 mm). The chest wall was the most commonly involved (98.6%), with an upper predominance on the ventral side (upper, 77.8% vs. lower, 55.9%, p < 0.001) and a lower predominance on the dorsal side (upper, 74.9% vs. lower, 91.8%, p = 0.02). Diaphragmatic involvement (78.1%) showed a right-side predominance (right, 73.8% vs. left, 55.6%, p < 0.001), whereas mediastinal plaques (42.7%) were more frequent on the left (right, 17.6% vs. left, 39.4%, p < 0.001). The extent and maximum length of plaques, and presence and severity of combined asbestosis, were significantly higher in the occupational exposure group (p < 0.05).

Conclusion: Pleural plaques in asbestos-exposed individuals are variable in number and size; and show a predominant distribution in the upper ventral and lower dorsal chest walls, right diaphragm, and left mediastinum. Asbestos mine workers have a higher extent of plaques and pulmonary fibrosis versus environmentally exposed individuals.

In plain English

This retrospective study described chest CT findings in 279 people with pleural plaques. All had chrysotile asbestos exposure from South Korean asbestos mines, had registered for asbestos damage relief, and were diagnosed with plaques between January 2011 and December 2014. Of these, 181 had occupational exposure (all also lived near the mines) and 98 had environmental exposure from living within 4 km of the mines. Plaques were single in 2.2% of people and on one side only in 3.6%. The chest wall was involved in 98.6%, the diaphragm in 78.1% (more often on the right) and the mediastinal pleura in 42.7% (more often on the left). Compared with the environmental group, the occupational group had longer plaques (mean maximum length 78.9 versus 60.8 mm), higher plaque extent scores, more calcification (88.9% versus 79.6%), and more lung fibrosis consistent with asbestosis (67.4% versus 53.1%). Maximum plaque width did not differ significantly between the groups. The authors concluded that mine workers had more extensive plaques and fibrosis than environmentally exposed residents. They noted possible selection bias, differences between CT scanners, and no tissue confirmation in uncertain cases.

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: Retrospective study of chest CT scans (cross-sectional comparison of an occupational exposure group and an environmental exposure group)
• Who was studied: 279 people registered with the Korea Environment Corporation for asbestos damage relief who were diagnosed with pleural plaques on CT from January 2011 to December 2014. 181 had occupational exposure (124 males, 57 females). 98 were residents within 4 km of asbestos mines (55 males, 43 females). All of the occupationally exposed people also lived near the mines.
• Exposure: Chrysotile asbestos from South Korean asbestos mines. Exposure came through work in asbestos mines, factories manufacturing asbestos-related products, or train stations transporting and unloading asbestos, or through living within 4 km of the mines. The mean occupational exposure duration was 8.4 years (range 0.1 to 32 years).
• Main results:
  • Among all 279 people, 6 (2.2%) had a single pleural plaque and 10 (3.6%) had plaques in only one side of the chest.
  • Calcified plaques were more common in the occupational group (88.9%) than in the environmental group (79.6%), p = 0.035.
  • The chest wall was the most common plaque location, involved in 98.6% of all subjects.
  • On the front (ventral) chest wall, plaques were more common in the upper half (77.8% vs. lower 55.9%, p less than 0.001). On the back (dorsal) chest wall, plaques were more common in the lower half (upper 74.9% vs. lower 91.8%, p = 0.021).
  • The diaphragm was involved in 78.1% of all subjects, more often on the right (73.8%) than the left (55.6%), p less than 0.001.
  • The mediastinal pleura was involved in 119 (42.7%) of all subjects.
  • Mediastinal plaques were more often on the left (39.4%) than the right (17.6%), p less than 0.001.
  • The distribution of plaques did not differ significantly between the occupational and environmental groups, except for the front-versus-back distribution on the chest wall.
  • Across all subjects, mean maximum plaque width was 5.4 mm (SD 2.7, range 1 to 20 mm) and mean maximum plaque length was 72.6 mm (SD 54.8, range 5 to 310 mm).
  • Maximum plaque length was longer in the occupational group (mean 78.9 mm, SD 55.8) than in the environmental group (mean 60.8 mm, SD 51.1), p less than 0.001.
  • Maximum plaque width did not differ significantly between the environmental group (mean 5.3 mm) and the occupational group (mean 5.5 mm), p = 0.792.
  • The total plaque extent score was higher in the occupational group (3.00) than in the environmental group (2.64), p = 0.027.
  • Pulmonary fibrosis consistent with asbestosis on CT was found in 122 (67.4%) of the occupational group and 52 (53.1%) of the environmental group, p = 0.018.
  • The asbestosis extent score was higher in the occupational group (0.75) than in the environmental group (0.57), p = 0.015.
  • The asbestosis fibrosis score was higher in the occupational group (1.24) than in the environmental group (0.99), p = 0.038.
  • Exposure duration was significantly correlated with maximum plaque length in the occupational group (p = 0.049) but not in the environmental group (p = 0.099).
• The authors' conclusion: The authors concluded that asbestos-related pleural plaques vary in number and size and are found mainly in the upper front and lower back chest walls, the right diaphragm and the left mediastinum. They also concluded that occupationally exposed mine workers had more extensive pleural plaques and pulmonary fibrosis than environmentally exposed residents.
• Limitations the authors state:
  • Selection bias: the applicants were not representative of people living near asbestos mines.
  • People with both occupational and environmental exposure may already have died (a healthy worker survivor effect).
  • CT slice thickness varied somewhat because different scanners at several institutions were used.
  • In equivocal cases, plaques were not confirmed by pathology, so some atypical lesions could be after-effects of past lung infections such as tuberculosis.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Asbestos Exposure, Environmental Exposure, Occupational Exposure, Chrysotile, CT Scan, Pulmonary Fibrosis, Diaphragm.

Related studies

• Epidemiologic characteristics of compensated occupational lung cancers among Korean workers — Y.S. Ahn, K.S. Jeong (2014)
• Environmental asbestos-related pleural plaque in southeast of Turkey — G. Ates, T. Yildiz, et al. (2010)
• Activity-Based Exposure Levels and Cancer Risk Assessment Due to Naturally Occurring Asbestos for the Residents Near Abandoned Asbestos Mines in South Korea — S. Lee, D. Kang, et al. (2021)
• Notes from the 2012 Annual Meeting of the Korean Society of Thoracic Radiology: asbestos-related thoracic diseases — J.S. Kim, J.G. Yi, et al. (2013)
• Incidence of Cancer and Asbestos-Related Diseases among Residents Living near Abandoned Asbestos Mines in South Korea: A Retrospective Cohort Study Using National Health Insurance Database — K. Kwak, K.E. Zoh, et al. (2021)
• Environmental pleural plaques in residents of a Quebec chrysotile mining town — A. Churg, L. DePaoli (1988)

Browse return to medical research.