Asbestos exposure among Finnish lung cancer patients: occupational history and fiber concentration in lung tissue

Our plain-English summary of Asbestos exposure among Finnish lung cancer patients: occupational history and fiber concentration in lung tissue, by A. Karjalainen, S. Anttila, L. Heikkilä, et al (American Journal of Industrial Medicine, 1993).

The study

• Authors: A. Karjalainen, S. Anttila, L. Heikkilä, P. Karhunen, H. Vainio
• Journal: American Journal of Industrial Medicine
• Published: 1993;23(3):461-71
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In a series of 65 surgically treated lung cancer patients, past exposure to asbestos was evaluated by personal interviews, and by scanning electron microscopy analyses of the mineral fibers in lung tissue. Lung tissue samples of 17 autopsied male office workers were analyzed as referents. According to occupational history, 37% of the lung cancer patients had definite or probable, 31% possible, and 32% unlikely exposure to asbestos. The fiber concentration in the lung tissue ranged from < 0.1 to 65 million fibers per gram dry tissue in the lung cancer group, and from < 0.1 to 0.8 million fibers per gram dry tissue in the reference group. In 26% of the lung cancer patients, but in none of the referents, the fiber concentration exceeded 1 million fibers per gram dry tissue. Most of the exposed patients had been employed in various construction jobs, and valuable information about the exposure levels could be obtained by the mineral fiber analyses. In general, there was a good accord between the exposure categorization and the fiber burden measured in the lung.

In plain English

This Finnish study examined past asbestos exposure in 65 lung cancer patients who came for planned lung surgery at Helsinki University Hospital between August 1988 and December 1990. They were consecutive cases from 2 of the 3 surgical units of the thoracic surgery department. Patients were interviewed about their work history. Two occupational hygienists, without knowing the tissue asbestos counts, rated each patient's exposure as definite, probable, possible or unlikely. Lung tissue from 54 of the patients was analysed by scanning electron microscopy and compared with tissue from 17 autopsied male office workers. By work history, 24 patients (37%) had definite or probable exposure, 19 in construction jobs. Patients' lung fiber levels ranged from less than 0.1 to 65 million fibers per gram of dry tissue; 14 (26%) exceeded 1 million. The office workers ranged from less than 0.1 to 0.8 million. The fibers were mainly anthophyllite, amosite and crocidolite; the authors noted their method may have significantly undercounted chrysotile. The authors concluded that asbestos exposure was common among Finnish lung cancer patients, that most exposed patients had worked in housebuilding, and that lung fiber levels generally agreed with the work-history ratings.

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: Series of consecutive lung cancer patients presenting for surgery, from 2 of the 3 surgical units of one hospital department. Exposure was assessed by interview-based classification and by electron-microscopic lung fiber counts, with a reference group of autopsied office workers.
• Who was studied: 65 lung cancer patients (55 men, 10 women; mean age 62) who came for planned pneumonectomy or lobectomy at the Department of Thoracic and Cardiovascular Surgery, Helsinki University Hospital, Finland, between August 1988 and December 1990. Lung tissue was obtained from 54 of them: 6 proved inoperable, 4 had no samples available and 1 refused the operation. The reference group was lung tissue from 17 male office workers autopsied in 1981-1982 after sudden deaths.
• Exposure: Past occupational asbestos exposure. It was classified from interviews as definite (group 1), probable (group 2), possible (group 3) or unlikely (group 4), without knowledge of the tissue asbestos counts. It was also measured as fibers per gram of dry lung tissue by scanning electron microscopy. Fiber types identified were anthophyllite, amosite or crocidolite, tremolite and chrysotile.
• Main results:
  • Of the 65 patients, 4 (6%) were classed as definite exposure (group 1), 20 (31%) as probable (group 2), 20 (31%) as possible (group 3) and 21 (32%) as unlikely (group 4).
  • Of the 24 patients with definite or probable exposure, 19 had been exposed in various construction jobs.
  • Among the 54 patients with tissue samples, fiber concentrations ranged from less than 0.1 to 65 million fibers per gram of dry tissue (mean 2.6 million). 14 patients (26%) exceeded 1 million.
  • The 1 million fibers per gram limit was exceeded in all 4 patients in group 1, 44% of patients in group 2, 11% in group 3 and 6% in group 4.
  • In the 17 male office workers (referents), fiber concentrations ranged from less than 0.1 to 0.8 million fibers per gram of dry tissue.
  • The Spearman rank correlation between fiber concentration (below vs. at or above 1 million fibers per gram) and exposure category was r = 0.52. The p-value appears in the scanned text as less than 0.001, split across a page break.
  • Of 11 heavily exposed patients with tissue samples, 8 (73%) exceeded 1 million fibers per gram of dry tissue.
  • Of 43 patients with moderate or no exposure, 6 (14%) exceeded 1 million fibers per gram of dry tissue.
  • The predominant fiber types in the patients' lungs were anthophyllite, amosite and crocidolite; only a few chrysotile fibers were found.
  • The highest concentration was 65 million fibers per gram of dry tissue, mainly anthophyllite, in a patient who had insulated heating pipes and boilers.
• The authors' conclusion: The authors concluded that asbestos exposure is common among Finnish lung cancer patients and that most exposed patients had worked in the housebuilding industry. They also concluded that lung fiber concentrations measured by electron microscopy generally correlated well with the work-history exposure ratings. These measurements gave useful information when exposure intensity was hard to judge from interviews, as with construction workers.
• Limitations the authors state:
  • Chrysotile fibers are mostly too thin to identify with this method, so chrysotile may have been significantly undercounted.
  • Referent tissue was paraffin-embedded and the counts were not corrected for this. A correction would reduce the referents' concentrations by as much as 30%.
  • Referents' occupational histories came from relatives, so occupational exposure among them cannot be completely ruled out.
  • Because the study was of operable patients, it lacks the most heavily exposed persons.
  • Low fiber counts in some probable-exposure patients may reflect low exposure or a sample taken from a lung site with a small concentration.
  • Patients could not give exact information on their own exposure levels.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Occupational History, Scanning Electron Microscopy (SEM), Mineral Fiber, Fibers Per Gram, Fiber Burden.

Related studies

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• Asbestos bodies in bronchoalveolar lavage fluid in relation to occupational history — A. Karjalainen, S. Anttila, et al. (1994)
• Lung cancer and past occupational exposure to asbestos. Role of p53 and K-ras mutations — K. Husgafvel-Pursiainen, A. Karjalainen, et al. (1999)
• Chrysotile fibers in tissue adjacent to laryngeal squamous cell carcinoma in cases with a history of occupational asbestos exposure — S.K. Wronkiewicz, V.L. Roggli, et al. (2020)
• Smoking, occupational risk factors, and bronchial tumor location: a possible impact for lung cancer computed tomography scan screening — M. Gonzalez, J.M. Vignaud, et al. (2012)
• Quantitation of asbestos and asbestos-like fibers in human lung tissue by hot and wet ashing, and the significance of their presence for survival of lung carcinoma and mesothelioma patients — K. Kayser, C. Becker, et al. (1999)

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