The Acute and Long-Term Effects of Middle East Sand Particles on the Rat Airway Following a Single Intratracheal Instillation

Abstract

Military personnel deployed in the Middle East have emphasized concerns regarding high levels of dust generated from blowing desert sand and the movement of troops and equipment. Airborne particulate matter levels (PM₁₀; PM < 10 μm) in the region may exceed 1500 μg/m³, significantly higher than the military exposure guideline (MEG) of 50 μg/m³. Increases in PM₁₀ have been linked to a rise in incidences of asthma, obstructive pulmonary disease, lung cancer, and cardiovascular diseases. Male Sprague-Dawley rats received a single intratracheal (IT) instillation of 1, 5, or 10 mg of Middle East PM₁₀ collected at a military occupied site in Kuwait, silica (positive control), or titanium dioxide (TiO₂; negative control) suspended in 400 μl sterile saline, or saline alone (vehicle control). Twenty-four hours, 3 d, 7 d and 6 mo postexposure (n = 15/group), organs including lung were evaluated for histopathological changes and for particle contaminants. Bronchoalveolar fluid (BALF) was also analyzed for cellular and biochemical parameters, including cytokines and chemokines. Instillation of silica resulted in early, pronounced, sustained inflammation indicated by significant increases in levels of total protein and neutrophils, and activities of lactate dehydrogenase activity and β-glucuronidase activity. Lower magnitude and transient changes using the same markers were observed in animals exposed to TiO₂ and Middle East PM₁₀. The results suggest that for acute exposures, this Middle East PM₁₀ is a nuisance-type dust with relatively low toxicity. However, since average deployment of military personnel to the Middle East is 180 d with potential for multiple follow-on tours, chronic exposure studies are needed to fully understand the pulmonary effects associated with Middle East PM exposure.

Acknowledgments

This work was supported by Defense Health Promotion work unit number 60262. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of the Army, Department of Defense, or the U.S. government. This article is approved for public release, distribution unlimited. The authors are military service members (or employees of the U.S. government). This work was prepared as part of their official duties. Title 17 U.S.C. §105 provides that copyright protection under this title is not available for any work of the United States government. Title 17 U.S.C. §101 defines a U.S. government work as a work prepared by a military service member or employee of the U.S. government as part of that person's official duties.

The experiments reported herein were conducted in compliance with the Animal Welfare Act and in accordance with the principles set forth in the “Guide for the Care and Use of Laboratory Animals,” Institute of Laboratory Animal Resources, National Research Council, National Academy Press, 1996. All procedures involving live animals were approved by the WPAFB Institutional Animal Care and Use Committee (IACUC) as protocol number F-WA-2005-0084A.

Notes

This article is not subject to U.S. copyright.