Characteristics of asbestos fibers in lung tissue from occupational and environmental asbestos exposure of lung cancer patients in Busan, Korea

Our plain-English summary of Characteristics of asbestos fibers in lung tissue from occupational and environmental asbestos exposure of lung cancer patients in Busan, Korea, by H.S. Jung, E.K. Park, J.S. Cha, et al (Scientific Reports, 2020).

The study

• Authors: H.S. Jung, E.K. Park, J.S. Cha, J.W. Lee, J.C. Lee, J. Jang, S. Kim, C. Oak, D.H. Yates, H. Kim
• Journal: Scientific Reports
• Published: 2020;10(1):20359
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The Asbestos Injury Relief Act in Korea requires that asbestos exposure be assessed through clinical examination and chest computed tomography (CT). However, a more specific measurement of asbestos characteristics in the lung tissue may be appropriate. We aimed to investigate the asbestos burden and characterize asbestos fibers in patients with lung cancer and ultimately assess the relationship between occupational and environmental asbestos exposure and lung cancer in Korea. We evaluated 37 lung cancer patients (LCPs) from Busan. The factors affecting asbestos burden in LCPs were analyzed using a multiple regression analysis. History of asbestos exposure (environmental/occupational), male sex, and old age were the main factors affecting asbestos burden in lung tissues of LCPs. These factors had an approximate 37% adjusted coefficient of determination. There was a significant difference in the length of asbestos fibers (4.06-37.6 µm vs. 4.26-91.7 µm) and aspect ratio (4.5-151.9 vs. 5.6-735.6) between those who were occupationally exposed to asbestos and those who were environmentally exposed (P < 0.01). Therefore, both environmental/occupational exposure to asbestos should be strongly managed to reduce the risk of lung cancer, and exposure should be assessed according to the characteristics of asbestos fibers in the lung tissue.

In plain English

This study measured asbestos fibers in lung tissue from 37 lung cancer patients in Busan, Korea. Normal lung tissue removed during surgery was digested and examined by transmission electron microscopy. By questionnaire, 6 patients, all men, reported work exposure to asbestos, and 31 reported living within 5 km of an asbestos factory, which the authors counted as environmental exposure. Asbestos fibers were found in 29 patients. The geometric mean burden was 0.120 million fibers per gram of dry lung in the occupational group and 0.059 million in the environmental group. That difference was not statistically significant. Patients aged 65 or older had a higher burden than younger patients (0.094 vs 0.049 million fibers per gram). Fiber lengths ranged from 4.06 to 37.6 µm in the occupational group and 4.26 to 91.7 µm in the environmental group, a significant difference. Length-to-width ratios also differed. In a statistical model, exposure history, sex and age together explained about 37% of the variation in burden. The authors concluded that both kinds of exposure should be managed to reduce lung cancer risk. The study was small and limited to Busan.

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: Analysis of asbestos fibers in lung tissue removed at surgery (pneumonectomy), measured by transmission electron microscopy after bleach digestion. All subjects had lung cancer; the study had no group of people without lung cancer.
• Who was studied: 37 lung cancer patients in Busan, Korea, randomly selected from patients scheduled for pneumonectomy who agreed to take part: 25 men and 12 women, mean age 61.5 years (range 28 to 79), 26 smokers and 11 nonsmokers
• Exposure: Self-reported asbestos exposure from a 16-item questionnaire. 6 patients (16.2%) reported occupational exposure: asbestos mine, dockyard insulation, boiler maintenance with asbestos cloth, pigpen construction with asbestos slates, and asbestos cement board manufacturing. 31 patients (83.8%) reported asbestos factories within a 5-km radius of their residence or living environment, counted as environmental exposure.
• Main results:
  • Asbestos fibers were detected in the lung tissue of 29 of the 37 patients: 23 in the environmental group and all 6 in the occupational group.
  • Geometric mean asbestos burden was 0.059 × 10^6 fibers/g dry lung in the environmental group and 0.120 × 10^6 fibers/g in the occupational group. This difference was not statistically significant (p = 0.0821). Smokers (0.067 × 10^6) and nonsmokers (0.076 × 10^6) also did not differ significantly.
  • Burden differed significantly by age: 0.049 × 10^6 fibers/g in patients under 65 versus 0.094 × 10^6 fibers/g in patients 65 or older (P less than 0.05). Burden did not differ significantly between men (0.070 × 10^6) and women (0.064 × 10^6).
  • In multiple regression, history of exposure (occupational versus environmental), sex and age were the main factors associated with asbestos burden. Together they had an adjusted coefficient of determination of 37.1%.
  • Fiber length ranged from 4.06 to 37.6 µm in the occupationally exposed patients and from 4.26 to 91.7 µm in the environmentally exposed patients. Aspect ratio ranged from 4.5 to 151.9 and from 5.6 to 735.6 respectively. Both differences were significant (P less than 0.01).
  • Fiber diameter did not differ significantly between the groups.
  • Fibers found in the 23 environmental-group patients (n = 93): 42 chrysotile, 5 amosite, 26 tremolite and 20 actinolite. Fibers found in the 6 occupational-group patients (n = 31): 1 chrysotile, 13 amosite, 2 crocidolite, 2 tremolite and 13 actinolite.
• The authors' conclusion: The authors concluded that both environmental and occupational asbestos exposure, and fiber characteristics (length, aspect ratio), were risk factors of lung cancer. They stated that environmental as well as occupational exposure should be managed to reduce the risk of lung cancer.
• Limitations the authors state:
  • The number of patients was small, and all came from the Busan region.
  • Because asbestos is not the major cause of lung cancer, asbestos detection rates in lung cancer are likely lower than in mesothelioma.
  • Asbestos burden can differ between studies because of differences in analytical sensitivity and tissue pretreatment methods, which limits comparison with earlier studies.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Aspect Ratio (Length-to-diameter ratio), Occupational Exposure.

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