title: Pulmonary effects in workers exposed to indium metal: A cross-sectional study.
abstract: OBJECTIVE
  Indium was added to the list of substances regulated by the Ordinance on Prevention of Hazards due to Specified Chemical Substances (OPHSCS) in 2013. Indium metal (IM), however, is not regulated by the OPHSCS due to insufficient information on pulmonary effects following exposure.
  
  
  METHODS
  From 2011 to 2013, a cross-sectional study was conducted on 141 IM-exposed workers at 11 factories. Subjective symptoms were assessed, including levels of serum biomarkers, spirometry readings and total and diffuse lung capacity. Krebs von den Lungen-6 (KL-6) and surfactant protein D (SP-D) were selected as biomarkers of interstitial pneumonia. Indium serum concentration (In-S) and personal air sampling data were used to estimate exposure. Subjects were categorized into 5 groups based on occupation and type of exposure: smelting, soldering, dental technician, bonding and other.
  
  
  RESULTS
  The highest level of In-S was 25.4 µg/l, and the mean In-S level was significantly higher in the smelting group than in other groups. In the smelting group, the prevalence of increased In-S levels was 9.1%, while that of abnormal KL-6 was 15.2%. A significant dose-effect relationship was observed between the In-S and KL-6 levels. No marked differences were observed between any of the groups in SP-D values, pulmonary symptoms, or pulmonary function test results. A total of 31% of the subjects worked in an environment with IM levels exceeding 0.3 µg/m(3), which requires a protective mask to be worn.
  
  
  CONCLUSIONS
  For workers exposed to IM, work environments should be monitored, appropriate protective masks should be worn, and medical monitoring should be conducted according to the OPHSCS.
authors.affiliation: Department of Preventive Medicine and Public Health, Keio University School of Medicine.
authors.forename: Makiko
authors.initials: M
authors.lastname: Nakano
authors.forename: Akiyo
authors.initials: A
authors.lastname: Tanaka
authors.forename: Miyuki
authors.initials: M
authors.lastname: Hirata
authors.forename: Satoko
authors.initials: S
authors.lastname: Iwasawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Omae
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D006801:Humans; D007204:Indium / Q000009:adverse effects*; D007564:Japan; D008297:Male; D009784:Occupational Diseases; D016273:Occupational Exposure / Q000032:analysis*; D012129:Respiratory Function Tests; D012131:Respiratory Insufficiency / Q000139:chemically induced*
chemical_list: D007204:Indium