Comparing Inhaled Ultrafine versus Fine Zinc Oxide Particles in Healthy Adults: A Human Inhalation Study

• Published in: American journal of respiratory and critical care medicine 2005-05, Vol.171 (10), p.1129-1135
• Main Authors: Beckett, William S, Chalupa, David F, Pauly-Brown, Andrea, Speers, Donna M, Stewart, Judith C, Frampton, Mark W, Utell, Mark J, Huang, Li-Shan, Cox, Christopher, Zareba, Wojciech, Oberdorster, Gunter
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Adult; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood coagulation. Blood cells; D. Environmental and Occupational Lung Disease; Electrocardiography; Environmental Exposure; Female; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods, hemostasis, fibrinolysis; Humans; Intensive care medicine; Male; Medical sciences; Middle Aged; Molecular and cellular biology; Particle Size; Pharmacology. Drug treatments; Respiratory system; Respiratory System - metabolism; Sputum - cytology; Zinc Oxide - administration & dosage; Zinc Oxide - chemistry; Zinc Oxide - metabolism; Zinc Oxide - toxicity
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.200406-837OC

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). We compared exposure-response relationships for respiratory, hematologic, and cardiovascular endpoints between ultrafine and accumulation mode zinc oxide particles. 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. 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. 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.