Characterizing the respiratory inflammatory response to geogenic dusts

Aim: To determine the respiratory inflammatory response to geogenic PM10 ( < 10 μm diameter particulate matter).

Methods: Samples were collected from two communities associated with open cut iron ore (Newman) and gold mining activities (Kalgoorlie). The PM10 fraction was extracted from the top 2 cm of a 1 m2 plot at each of the sites. Adult BALB/c mice were exposed to 10, 30 or 100 μg of PM10 by intranasal instillation (in 50 μL of saline + 0.05% Tween-80). Control mice received 100 μg of polystyrene beads (2.5 μm or 10 μm) or vehicle alone. Mice were euthanased and bronchoalveolar lavage (BAL) fluid was collected for assessment of inflammation and cytokines (MIP-2, IL-6 and IL-1β) 3, 6, 12, 24 or 168 h post exposure. Metal content in the PM10 samples was assessed by ICP-MS and preparations were examined under electron microscopy to obtain particles size distributions.

Results: The chemical and physical properties of the geogenic particles varied with considerably more Fe and a much wider particle size distribution in the PM10 from Newman. Both geogenic particle preparations resulted in dose dependent increases in neutrophils and cytokines (MIP-2 and IL-6) in the BAL. Quantitatively the kinetics of the response was comparable, however, the magnitude of the response was greater in mice exposed to PM10 from Newman. The instillation of 2.5 μm polystyrene beads resulted in a significant neutrophilia comparable to the geogenic response; however, the production of proinflammatory cytokines was minimal.

Conclusions: The unique physical and chemical properties of geogenic particles induce an inflammatory response in the lung. This has important implications for respiratory health in communities exposed to high particulate loads of geogenic origin such as those associated with open cut mining activities.