Dust and Human Health - Mineral Dust: A Key Player in the Earth System - page 395

Fig. 15.4 Dust storm at Kandahar Airfield, 2006, Afghanistan. (Photograph courtesy of Jared
Abraham, USGS)
(Korenyi-Both et al. 1992 ). Analysis of dust samples, after a high incidence of
respiratory disease, revealed the presence of many fine-grained (<1 m) sand
particles, but most cultures for pathogens were negative. The abundance of
respirable particles, the authors suggest, induced hyperergia or an increased
sensitivity to allergens and overwhelmed pulmonary macrophages, thereby reducing
their capacity to protect against infectious agents. Kelsall et al. ( 2004 ) found no
increase in respiratory disease related to dust storms in a study of deployed military
personnel. Studies are ongoing to understand exposures and related health effects
for currently or recently deployed troops to Iraq and Afghanistan (Engelbrecht et al.
2008 ; Szema et al. 2010 ; King et al. 2011 and others).
The health effects from exposures to dusts of asbestos have been known for
decades and include asbestosis, pleural plaques or pleural abnormalities, mesothe-
lioma cancer, lung cancer, tracheal cancer, and plausibly cancers of some other
organs (NIOSH 2011 ). These diseases have a long latency period (time from
exposure until disease presentation), making them difficult to study. As a result,
in spite of decades of research, considerable uncertainties remain regarding how
asbestos and so-called respirable elongate mineral particles or REMPs cause
toxicity (NIOSH 2011 ). Contributing factors are thought to include (1) their length,
which inhibits engulfment and clearance by the alveolar macrophages, (2) their
biodurability in the lungs, and (3) their ability to trigger inflammation and generate
reactive oxygen species (the latter, e.g., via release of iron from the fiber surfaces)
(Aust et al. 2011 ).