Airborne Matter “Geotoxicology”: Public Health, Policy, and Environmental Security

Airborne particulate matter (PM) has been documented or hypothesized as the cause of many adverse health effects. Most focus has been on occupational or environmental exposures to anthropogenic PM (e.g., industrial mineral dusts or fossil-fuel combustion byproducts).  However, geogenic PM (produced from the Earth by natural processes) and geoanthropogenic PM (produced from natural sources but modified by human activities) are increasingly of concern as potential agents of toxicity.
Geotoxicology can be defined as the study of the toxicological characteristics and potential health effects of geo(anthropo)genic PM and PM sources. Acute exposures to high PM are associated with worsened asthma and pulmonary inflammation, heart attacks, and cardiovascular problems. Diseases can result from inhalation of dust-borne pathogens such as the soil fungus that is the etiologial agent of Valley Fever. PM can contain bioaccessible (readily dissolved in the body’s fluids), potentially toxic heavy metals or metalloids. Acutely bioreactive PM, such as concrete dusts, wildfire ash, and volcanic fog can trigger acute irritation or tissue damage of the respiratory tract, eyes, and skin. Biodurable (insoluble) PM such as asbestos, crystalline silica, and coal dusts can persist in the body for years and, at high doses, cause fibroses of the lungs. Chronic interactions of biodurable minerals with the body (such as oxidation-reduction cycling, generation of reactive oxygen species, and immune responses) may lead to lung cancer, mesothelioma, and other cancers. However, many key questions remain, such as the exact mechanisms by which many types of PM cause disease, and the levels of exposure above which various PM types pose a substantial health risk.
Geotoxicology input, best accomplished collaboratively by scientists from a wide range of disciplines in the earth and health sciences, will be key for many PM-related policy and environmental security issues. Examples include: understanding and managing risks associated with living on or near asbestos-containing rocks; appropriately factoring geogenic PM into air quality regulations at local to regional scales, particularly as arid regions and dust sources shift in response to climate change or human stresses; and understanding how human practices and policies that influence PM generation in one continent or country may ultimately have an impact on public health, policy, and environmental security in countries downwind.