title: Comparing inhaled ultrafine versus fine zinc oxide particles in healthy adults: a human inhalation study.
abstract: BACKGROUND
  Zinc oxide is a common, biologically active constituent of particulate air pollution as well as a workplace toxin. Ultrafine particles (< 0.1 microm diameter) are believed to be more potent than an equal mass of inhaled accumulation mode particles (0.1-1.0 microm diameter).
  
  
  OBJECTIVE
  We compared exposure-response relationships for respiratory, hematologic, and cardiovascular endpoints between ultrafine and accumulation mode zinc oxide particles.
  
  
  METHODS
  In a human inhalation study, 12 healthy adults inhaled 500 microg/m3 of ultrafine zinc oxide, the same mass of fine zinc oxide, and filtered air while at rest for 2 hours.
  
  
  RESULTS
  Preexposure and follow-up studies of symptoms, leukocyte surface markers, hemostasis, and cardiac electrophysiology were conducted to 24 hours post-exposure. Induced sputum was sampled 24 hours after exposure. No differences were detected between any of the three exposure conditions at this level of exposure.
  
  
  CONCLUSIONS
  Freshly generated zinc oxide in the fine or ultrafine fractions inhaled by healthy subjects at rest at a concentration of 500 microg/m3 for 2 hours is below the threshold for acute systemic effects as detected by these endpoints.
authors.affiliation: Department of Envrionmental Medicine, University of Rochester School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Avenue, Box EHSC, Rochester, New York 14642, USA. bill_beckett@urmc.rochester.edu
authors.forename: William S
authors.initials: WS
authors.lastname: Beckett
authors.forename: David F
authors.initials: DF
authors.lastname: Chalupa
authors.forename: Andrea
authors.initials: A
authors.lastname: Pauly-Brown
authors.forename: Donna M
authors.initials: DM
authors.lastname: Speers
authors.forename: Judith C
authors.initials: JC
authors.lastname: Stewart
authors.forename: Mark W
authors.initials: MW
authors.lastname: Frampton
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Utell
authors.forename: Li-Shan
authors.initials: LS
authors.lastname: Huang
authors.forename: Christopher
authors.initials: C
authors.lastname: Cox
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Günter
authors.initials: G
authors.lastname: Oberdörster
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D004562:Electrocardiography; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D012137:Respiratory System / Q000378:metabolism; D013183:Sputum / Q000166:cytology; D015034:Zinc Oxide / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*
chemical_list: D015034:Zinc Oxide
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