title: Causal relationship between indium compound inhalation and effects on the lungs.
abstract: BACKGROUND
  Recent case reports and epidemiological studies suggest that inhalation of indium dust induces lung damage.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo 160-8582, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Nakano
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Omae
authors.forename: Akiyo
authors.initials: A
authors.lastname: Tanaka
authors.forename: Miyuki
authors.initials: M
authors.lastname: Hirata
authors.forename: Takehiro
authors.initials: T
authors.lastname: Michikawa
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Kikuchi
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yoshioka
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nishiwaki
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Chonan
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000633:toxicity*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007204:Indium / Q000097:blood / Q000633:toxicity*; D019570:Inhalation Exposure / Q000009:adverse effects*; D007564:Japan / Q000453:epidemiology; D008171:Lung Diseases / Q000139:chemically induced* / Q000453:epidemiology; D008297:Male; D019370:Observation; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood; D012016:Reference Values
chemical_list: D000395:Air Pollutants, Occupational; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D007204:Indium