Causal relationship between indium compound inhalation and effects on the lungs

Makiko Nakano, Kazuyuki Omae, Akiyo Tanaka, Miyuki Hirata, Takehiro Michikawa, Yuriko Kikuchi, Noriyuki Yoshioka, Yuji Nishiwaki, Tatsuya Chonan

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)


Department of Preventive Medicine and Public Health, School of Medicine, Keio University-Background: Recent case reports and epidemiological studies suggest that inhalation of indium dust induces lung damage. Objectives: To elucidate the dose-dependent effects of indium on the lungs and to prove a causal relationship more clearly. Methods: A baseline observation was conducted on 465 workers currently exposed to indium, 127 workers formerly exposed to indium and 169 workers without indium exposure in 12 factories and 1 research laboratory from 2003 to 2006. Indium in serum (In-S) was determined as an exposure parameter, and its effects on the lungs were examined. Results: The means of In-S in the current, former and no exposure workers were 8.35, 9.63 and 0.56 ng/ml, respectively. The current and former exposure workers had significantly higher levels of KL-6, and showed significant dose-dependent increases in KL-6, SP-D, and SP-A. Current exposure workers with In-S of 3 ng/ml or above demonstrated a significant increase of KL-6 in both GM and prevalence exceeding the reference value. Approximately a quarter of the former exposure workers had interstitial changes as seen on chest HRCT. In-S of exposed workers who had been working before improvements of the working environment (Group Bef) and those who started working after improvements (Group Aft) were 12.29 and 0.81 ng/ml, respectively. Adjusted odds ratios indicated 87%, 71% and 44% reductions among Group Aft workers who exceeded the reference values of KL-6, SP-D and SP-A, respectively. Conclusion: Dose-dependent lung effects due to indium exposure were shown, and a decrease of indium exposure reduced the lung effects. An In-S value of 3 ng/ml may be a cut-off value which could be used to prevent early effects on the lungs.

Original languageEnglish
Pages (from-to)513-521
Number of pages9
JournalJournal of occupational health
Issue number6
Publication statusPublished - 2009 Nov


  • Cross-sectional study
  • HRCT
  • Indium
  • Interstitial pneumonitis
  • KL-6
  • SP-D

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health


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