Assessment of geographical variation in the respiratory toxicity of desert dust particles

Abstract

The health consequences of sand particle inhalation are incompletely understood. This project evaluated the respiratory toxicity of sand particles collected at military bases near Fort Irwin USA, in Iraq (Camp Victory, Taji and Talil), and Khost Afghanistan. Our primary focus was on assessing the role of soluble metals in the respiratory toxicity of the sand particles using in vitro and in vivo methods. Replicating rat type II alveolar cell cultures (RLE-6TN) were exposed to sand extracts or vehicle control in serum-free media for ≤24 h. Cytotoxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and assessment of lactate dehydrogenase leakage. The relative in vitro cytotoxicity of the sand extracts was Taji ≈ Talil > Afghanistan > Camp Victory ≈ Fort Irwin. We also assessed extracts of Camp Victory, Afghanistan, and Taji sand for acute and delayed pulmonary toxicity in rats following intratracheal administration. Assessments included biochemical analysis of bronchoalveolar lavage fluid (BALF) and lung histopathology. The in vitro cytotoxicity assay results were partially predictive of in vivo responses. The more cytotoxic Taji sand extract induced an acute irritant response in rats following intratracheal administration. Rats given the less cytotoxic Camp Victory sand extract had minimal biochemical or cytological BALF changes whereas rats given either the Afghanistan or Taji sand extracts demonstrated BALF changes that were suggestive of mild lung inflammation. Unexpectedly, we observed similar lung pathology in all extract-exposed rats. The results of our study can be used to prioritize future particle inhalation studies or guide epidemiological study design.

• Cytotoxicity
• dust inhalation
• in vitro
• in vivo
• particle toxicity
• pulmonary toxicity
• rat

Acknowledgements

We acknowledge Bobbi McQuown, Elise Grover, and the staff of the NCSU College of Veterinary Medicine’s Laboratory Animal Resource, Histology, and Central Procedures Laboratories for their assistance with this project.

Disclaimers

Several authors are military service members (or employee of the US Government) and this work was prepared as part of their official duties. Title 17 USC §105 provides that “Copyright protection under this title is not available for any work of the United States Government”. Title 17 USC §101 defines all US Government work as a work prepared by a military service member or employee of the US Government as part of that person’s official duties.