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Talc and Amosite/Crocidolite Preferentially Deposited in the Lungs of Nonoccupational Female Lung Cancer Cases in Urban Areas of Japan
Hiroyuki Yamada, Hisako Hashimoto, Masako Akiyama, Yoshinori Kawabata, and Kazuro Iwai
Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose, Tokyo, Japan
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 bodies (FBs) and uncoated fibers (UFs), which had length longer than 5 µm 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. Key words: asbestos, female, ferruginous bodies, fibrous talc, lung cancer, mineral fibers, nonoccupational exposure. Environ Health Perspect 105:504-508 (1997)
Address correspondence to Hiroyuki Yamada, Division of Pathology, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, 3-1-24, Matsuyama, Kiyose, Tokyo, 204, Japan.
We thank the following doctors for their generous cooperation in sending lung tissue samples: M. Tamura (Iwate Medical University Internal Medicine, Iwate), S. Kusama (Shinshu University Internal Medicine, Nagano), E. Tsuchiya (Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo), T. Arai (National Sanatorium, Nakano Hospital, Tokyo), A. Koyama (Japan Anti-Tuberculosis Association, Fukujuji Hospital, Tokyo), I. Sakurai (Nihon University Itabashi Hospital, Tokyo), M. Fukuoka (Osaka Prefectural Habikino Hospital, Osaka), and T. Tachibana (Osaka Prefectural Hospital, Osaka). We also thank N. Kohyama, National Institute of Industrial Medicine, Kawasaki, Japan, for critical technical advice on analytical electron microscopy, and we thank A. Churg, University of British Columbia, Vancouver, Canada, for critical comments on this paper.
This study was supported by a grant from the Environmental Agency of the Japanese Government.
Received 30 September 1996; accepted 8 January 1997.
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