| Human Pulmonary Responses to Experimental Inhalation of High Concentration Fine and Ultrafine Magnesium Oxide Particles Ware G. Kuschner,
1,2,3
Hofer Wong,
3
Alessandra D'Alessandro,
1,3
Patricia Quinlan,
1
and Paul D. Blanc
1,2,3
1
Division of Occupational and Environmental Medicine, Department of Medicine;
2
Division of Pulmonary and Critical Care Medicine, Department of Medicine; and
3
Cardiovascular Research Institute, University of California, San Francisco, California 94717 USA Abstract
Exposure to air polluted with particles less than 2.5 µm in size is associated epidemiologically with adverse cardiopulmonary health consequences in humans. The goal of this study was to characterize human pulmonary responses to controlled experimental high-dose exposure to fine and ultrafine magnesium oxide particles. We quantified bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations in six healthy volunteers 18 to 20 hr after inhalation of fine and ultrafine magnesium oxide particles produced from a furnace system model. We compared postexposure studies with control studies from the same six subjects. Mean ± standard deviation (SD) cumulative magnesium dose was 4,138 ± 2,163 min  mg/m 3 . By weight, 28% of fume particles were ultrafine (<0.1 µm in diameter) and over 98% of fume particles were fine (<2.5 µm in diameter) . There were no significant differences in BAL inflammatory cell concentrations, BAL interleukin (IL) -1, IL-6, IL-8, tumor necrosis factor, pulmonary function, or peripheral blood neutrophil concentrations postexposure compared with control. Our findings suggest that high-dose fine and ultrafine magnesium oxide particle exposure does not produce a measurable pulmonary inflammatory response. These findings are in marked contrast with the well-described pulmonary inflammatory response following zinc oxide particle inhalation. We conclude that fine and ultrafine particle inhalation does not result in toxicity in a generic manner independent of particle composition. Our findings support the concept that particle chemical composition, in addition to particle size, is an important determinant of respiratory effects. Key words : BAL, bronchoalveolar lavage, cytokines, fine particles, inhalation, magnesium, occupational, pulmonary function, ultrafine particles. Environ Health Perspect 105:1234-1237 (1997) .
Address correspondence to P.D. Blanc, University of California, San Francisco, Division of Occupational and Environmental Medicine, 350 Parnassus Avenue, Suite 609, San Francisco, CA 94117 USA. Current addresses are Division of Pulmonary and Critical Care Medicine, Veterans Affairs Palo Alto Health Care System, Stanford University School of Medicine, Palo Alto, California, for W.G. Kuschner and Ist. Di Medicina del Lavoro e Tossicologia Professionale e Ambientale, Universita'Degli Studi di Perugia, Perugia, Italy, for A. D'Alessandro. The authors thank Homer Boushey for assistance with bronchoscopy and Jane Liu for assistance with the BAL protein assay. Supported in part by National Research Service Award No. HL07185 and a Foundation for Occupational Health and Research Award (W.G.K.) , and Research Career Development Award No. HL03225 (P.D.B.) . Received 27 December 1996 ; accepted 26 August 1997.
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