Talc and amosite/crocidolite preferentially deposited in the lungs of nonoccupational female lung cancer cases in urban areas of Japan

Our plain-English summary of Talc and amosite/crocidolite preferentially deposited in the lungs of nonoccupational female lung cancer cases in urban areas of Japan, by H. Yamada, H. Hashimoto, M. Akiyama, et al (Environmental Health Perspectives, 1997).

The study

• Authors: H. Yamada, H. Hashimoto, M. Akiyama, Y. Kawabata, K. Iwai
• Journal: Environmental Health Perspectives
• Published: 1997;105(5):504-8
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

To analyze the correlation between asbestos lung burden and lung cancer, lungs of 211 female cases with and without lung cancer were examined. Phase-contrast microscopic (PCM) counting of ferruginous (FBs) and uncoated fibers (UFs), which had length longer than 5 microns and aspect ratios greater than 3:1, revealed a significantly higher level of FBs plus UFs in urban lung cancer cases than urban non-lung cancer cases (1380.5 vs. 550.3; p < 0.001). No difference was noted between rural lung cancer and non-lung cancer cases. Analytical electron microscopic studies identified various kinds of mineral fibers with an aspect ratio greater than 3:1 in the lung tissue including chrysotile, actinolite/tremolite, amosite/crocidolite, fibrous talc, mica, silica, iron, wollastonite, chlorite, kaoline, and others. The most frequently detected fibers were thin, short chrysotile fibers, most of which could not be found by PCM, followed by relatively thick, long actinolite/tremolite fibers, fibrous talc, and in a smaller number, amosite/crocidolite of intermediate length and width. Amosite/crocidolite and fibrous talc counts in urban lung cancer cases were greater than those of urban non-lung cancer cases, rural lung cancer, and rural non-lung cancer cases; these findings were consistent with PCM analysis. Therefore, it is suggested that fibers detected in PCM observation may be mainly amosite/crocidolite with some parts fibrous talc and that fibrous talc in urban environments may be another candidate for carcinogenic or cocarcinogenic factors of female lung cancer.

In plain English

This study compared mineral fibers in the lungs of 211 Japanese women with no asbestos-related job history. The women were 103 with lung cancer, mostly adenocarcinoma, and 108 age-matched women without lung cancer, from urban (Tokyo, Osaka) and rural (Iwate, Nagano) areas. Using phase-contrast light microscopy, the authors counted coated (ferruginous) bodies plus uncoated fibers per gram of dry lung. Urban lung cancer cases averaged 1380.5, against 550.3 in urban women without lung cancer (p = 0.001). Rural averages were 151.4 and 125.6, a difference that was not statistically significant. Non-smokers alone showed a similar pattern. Electron microscopy of 28 non-smokers (7 per group) identified chrysotile, actinolite/tremolite, amosite/crocidolite, fibrous talc, mica and other fibers. Among fibers longer than 5 micrometres, amosite/crocidolite and fibrous talc were highest in urban lung cancer cases. Chrysotile and actinolite/tremolite were highest in rural women without lung cancer. The authors suggested the light-microscopy fibers may be amphibole, especially amosite/crocidolite, and fibrous talc. They called for further study of fibrous talc in female lung cancer and noted talc might come from surgical gloves.

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: Comparison of lung fiber burden in women with lung cancer and age-matched women without lung cancer (case-control comparison of lung tissue), using phase-contrast light microscopy and analytical transmission electron microscopy
• Who was studied: 211 women over 40 with no asbestos-related occupational history: 103 lung cancer cases (83 adenocarcinomas) and 108 age-matched non-lung cancer cases from urban (Tokyo and Osaka) and rural (Iwate and Nagano Prefecture) areas of Japan. Groups were 75 urban lung cancer, 76 urban non-lung cancer, 28 rural lung cancer and 32 rural non-lung cancer. Lung tissue came mostly from surgery, with some non-lung cancer samples from autopsies. Dates of collection were not given.
• Exposure: Nonoccupational (environmental) fiber burden in lung tissue. Measured as ferruginous bodies and uncoated fibers longer than 5 micrometres with aspect ratio greater than 3:1 by light microscopy. Electron microscopy identified fiber types including chrysotile, actinolite/tremolite, amosite/crocidolite and fibrous talc.
• Main results:
  • By light microscopy, urban lung cancer cases had a higher average count of ferruginous bodies plus uncoated fibers than urban non-lung cancer cases: 1380.5 vs. 550.3 per gram dry lung weight, p = 0.001
  • Rural lung cancer and rural non-lung cancer cases had average counts of 151.4 vs. 125.6 per gram dry lung weight. The authors saw no statistically significant difference between them (p greater than 0.5).
  • Among nonsmokers only, average counts were 1525.8 (urban lung cancer), 599.2 (urban non-lung cancer), 184.8 (rural lung cancer) and 233.2 (rural non-lung cancer) per gram dry lung weight. The urban lung cancer group was again significantly higher.
  • Ferruginous bodies were found in 123 (58.3%) and uncoated fibers in 186 (88.2%) of the 211 cases
  • In electron microscopy of 7 nonsmokers per group, amosite/crocidolite and fibrous talc fibers longer than 5 micrometres were highest in the urban lung cancer group. Fibrous talc counts were much higher than amosite/crocidolite counts.
  • For fibers longer than 5 micrometres, chrysotile counts were much greater in the rural non-lung cancer group than in the other three groups. This group also had the highest actinolite/tremolite counts.
  • Only 15.8% of chrysotile fibers were longer than 5 micrometres, compared with 63.5% of amosite/crocidolite, 82.3% of actinolite/tremolite and 75.6% of fibrous talc fibers
• The authors' conclusion: The authors concluded that urban counts were greater than rural ones and that fibers counted by light microscopy may be amphibole (especially amosite/crocidolite) and fibrous talc. They concluded that chrysotile and actinolite/tremolite may not affect lung carcinogenesis, particularly in rural areas. They also concluded that further studies are required on the role of fibrous talc in female lung cancer.
• Limitations the authors state:
  • Talc in the samples could have come from surgical gloves during operation or autopsy. The authors noted that higher talc counts were found only in the urban lung cancer group.
  • Light microscopy cannot detect the shorter and thinner fibers
  • Electron microscopy examines less tissue, giving more sampling bias and counting variability than light microscopy
  • Unused Nuclepore filters contained numerous short chrysotile fibers, mostly shorter than 0.1 micrometres

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Asbestosis, Crocidolite, Lung cancer, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Talc, Amosite, Crocidolite, Lung Cancer, Aspect Ratio (Length-to-diameter ratio), Mineral Fiber, Chrysotile, Actinolite.

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