title: Five-year cohort study: emphysematous progression of indium-exposed workers.
abstract: BACKGROUND
  Dose-dependent adverse lung effects due to indium exposure have been reported in a cross-sectional study. This is a 5-year longitudinal cohort study of indium-exposed and unexposed workers, assessing indium exposure levels and its clinical lung effects.
  
  
  METHODS
  From 2008 to 2011, a 5-year follow-up study was conducted on 40 unexposed and 240 workers formerly or currently exposed to indium at 11 factories. Indium exposure was assessed by serum indium (In-S) (μg/L). Lung effects were assessed by subjective symptoms, serum biomarkers, spirometry, and chest high-resolution CT scan. Effect biomarkers used were Krebs von den Lungen and surfactant protein D.
  
  
  RESULTS
  Mean values of In-S, Krebs von den Lungen, and surfactant protein D among the workers exposed to indium at baseline declined during the 5-year follow-up by 29.8%, 27.2%, and 27.5%, respectively. Of the exposed subjects with In-S levels > 20 μg/L, 26.3% experienced emphysematous progression on high-resolution CT scan. Ninety percent (18 of 20) of workers with emphysematous progression during follow-up were current smokers at baseline, and a trend of increasing incidence of emphysematous progression at higher In-S levels was observed among the smokers (P = .005). Emphysematous changes among subjects with In-S levels > 20 μg/L were likely to progress, after adjusting for age, mean duration since initial indium exposure, and smoking history (OR = 10.49, 95% CI = 1.54-71.36).
  
  
  CONCLUSIONS
  Long-term adverse effects on emphysematous changes were observed. The results suggest workers exposed to indium with In-S levels > 20 μg/L should be immediately removed from exposure.
authors.affiliation: From the Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo. Electronic address: nakano.makiko@z8.keio.jp.
authors.forename: Makiko
authors.initials: M
authors.lastname: Nakano
authors.affiliation: From the Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Omae
authors.affiliation: From the Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Uchida
authors.affiliation: Environmental Epidemiology Section, Center for Environmental Health Sciences, National Institute for Environmental Studies, Tsukuba.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Michikawa
authors.affiliation: From the Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yoshioka
authors.affiliation: Environmental Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Hirata
authors.affiliation: Environmental Medicine, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors.forename: Akiyo
authors.initials: A
authors.lastname: Tanaka
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007204:Indium / Q000009:adverse effects*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D011656:Pulmonary Emphysema / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology; D037663:Pulmonary Surfactant-Associated Protein D / Q000378:metabolism; D012189:Retrospective Studies; D013147:Spirometry; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D037663:Pulmonary Surfactant-Associated Protein D; D007204:Indium