Published ahead of print on February 25, 2005, doi:10.1164/rccm.200406-837OC Am. J. Respir. Crit. Care Med., Volume 171, Number 10, May 2005, 1129-1135 A more recent version of this article appeared on May 15, 2005
Submitted on July 23, 2004 Comparing Inhaled Ultrafine vs Fine Zinc Oxide Particles in Healthy Adults:A Human Inhalation StudyWilliam S Beckett1*,1 Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA; Department of Medicine, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA, 2 Department of Medicine, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA, 3 Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA, 4 Department of Medicine, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA; Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA, 5 Department of Biostatistics, University of Rochester School of Medicine and Dentistry: Division of Epidemiology, Statistics and Prevention, Rochester, NY, USA, 6 National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA * To whom correspondence should be addressed. E-mail: Bill_Beckett{at}urmc.rochester.edu.
Rationale: Zinc oxide is a common, biologically active constituent of particulate air pollution as well as a workplace toxin. Ultrafine particles (less than 0.1 micrometer diameter) are believed to be more potent than an equal mass of inhaled accumulation mode particles (0.1 to 1.0 micrometer diameter). Objectives: 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 micrograms per cubic meter of ultrafine zinc oxide, the same mass of fine zinc oxide, and filtered air while at rest for two hours. Measurements and Main Results: Pre-exposure 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 micrograms per cubic meter for two hours is below the threshold for acute systemic effects as detected by these end points. Key words: air pollution; metal fume fever; ultrafine particles
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