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Investigation into the Pulmonary Health Effects of Dust and Sea Spray Aerosol from the Salton Sea on Mice using Whole Body Exposure Chamber
QI LI, Ryan Drover, Trevor Biddle, Mia Rose Maltz, David Lo, David R. Cocker III, University of California, Riverside
Abstract Number: 284
Working Group: Aerosol Exposure
Abstract
The Salton Sea is a 345mi2 inland saline lake located in California imperial counties and fed by agricultural runoff. Due to a 2003 ordinance diverting water to San Diego county, the Salton Sea has been drying rapidly, exposing more lakebeds and causing the water to become hypersaline. This has caused significant ecology changes, resulting in algal blooms, fish and migratory bird die-offs, and an increase in dust production. As a result, serious concerns have been raised over the air quality in nearby areas. Surrounding communities suffer from one of the highest rates of childhood asthma in California at 20% - 22.4%, compared to an average of 14.5% for the rest of the state. While many types of particles may potentially contribute to the health effects, we focused on the dust particles and water spray aerosols. In this study, mice were exposed to either an aerosolized aqueous extract from dust surrounding the Salton Sea, filtered and aerosolized Salton Sea water, Alternaria aerosol, or filtered and aerosolized Pacific Ocean water separately for 7-day. Alternaria, a known effective fungal allergen, was used to set up a reference for an inflammatory lung response. Pacific Ocean sample served as a control to account for the potential inherent effects of saline water. Exposure experiments were conducted in the newly established dual animal whole body exposure chambers (540L per each). Particles were generated continuously with consistent size distribution and concentration of 1.5 mg m-3 through experiments. Chemical component analysis was done by using a ToF-AMS. Seasonal component fraction change was found with organics varying from 5.9% to 19.7% in Salton Sea sprayed particles and from 12.1% to 19.9% in Pacific Ocean sprayed particles, as compared to high organic fraction of 82.3% in Alternaria particles and 29.7% in Salton Sea dust extraction. Flow cytometry, NanoString analysis and histology were used to characterize the immune response due to the exposure. Our results confirmed that Alternaria caused strong inflammatory response from mice. Conversely, Pacific Ocean aerosol failed to trigger an inflammatory response. The Salton Sea dust extract was able to trigger a strong inflammatory response distinct from Alternaria. Despite cellular infiltrates in the dust exposure, Salton Sea water failed to recruit key inflammatory cells. However, the Salton Sea water aerosol was capable of generating a small, but significant change in inflammatory gene expression distinct from the other exposures. Detailed discussion on gene expression change will be presented. Thus, the Salton Sea water spray may play a key role in the progression to asthma or other inflammatory diseases despite the inability to generate asthma alone in this study.