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Source-Apportioned Coarse Particulate Matter Exacerbates Allergic Airway Responses in Mice
Citation:
Hargrove, M., J. Mcgee, E. Gibbs-Flournoy, C. Wood, Y. Kim, Ian Gilmour, AND S. Gavett. Source-Apportioned Coarse Particulate Matter Exacerbates Allergic Airway Responses in Mice. INHALATION TOXICOLOGY. Informa Healthcare USA, New York, NY, 30(11):405-415, (2018). https://doi.org/10.1080/08958378.2018.1542047
Impact/Purpose:
The Cleveland Multiple Air Pollutant Study (CMAPS) was an intensive study of ambient air quality in the Cleveland airshed conducted by the U.S. EPA from August 2008 to October 2010. CMAPS is one of the first comprehensive studies of ambient air particulate matter (PM) characteristics and sources over local and regional scales. The Cleveland area was an ideal location for this study as regional coal combustion from the nearby Ohio River Valley provided a significant component of pollution (Keeler et al., 2006; White et al., 2009). Size-fractionated PM (coarse, fine, and ultrafine) samples were collected using high-volume (ChemVol) air samplers at an urban site (G.T. Craig (GTC) located near downtown Cleveland) and a rural site (Chippewa Lake monitor (CLM) located 53 km southwest of Cleveland) from July 2009 to June 2010, and then chemically analyzed. The resulting speciated PM data were apportioned by EPA positive matrix factorization to identify emission sources for each size fraction and location. A recent manuscript examines the chemistry and sources of PM collected for the CMAPS study and is currently undergoing internal EPA review and clearance (Kim et al., 2016). The source apportionment results demonstrated that PM samples collected at GTC and CLM were enriched with local industrial sources (e.g., steel plant and coal-fired power plant) but their contributions were influenced by meteorological conditions and the emission source operation conditions. The objective of this study was to evaluate the relationship between PM sources and biological markers of toxicity for coarse particles collected in the CMAPS study. This research examined the toxicity of coarse particulate matter in a house dust mite (HDM) model of allergic asthma. In this study we examined an array of factors from the PM samples collected in the CMAPS study, including particle size, location (urban – GTC vs. rural – CML), and source-rich components (e.g. traffic, steel, soil) as determined by source apportionment. Analysis of the chemical differences in conjunction with biological endpoints allowed determination of the key components responsible for exacerbation of allergic airways disease endpoints.
Description:
Exposure to coarse particulate matter (PM) is associated with lung inflammation and exacerbation of respiratory symptoms in sensitive populations, but the degree to which specific emission sources or other components of PM contribute to these effects is unclear. We examined whether coarse PM samples enriched with diverse sources differentially exacerbate responses in a mouse model of allergic airway disease. Coarse PM was collected weekly (July 2009 - June 2010) from urban (G.T. Craig, GTC) and rural (Chippewa Lake Monitor, CLM) sites in the Cleveland, Ohio area. Source apportionment results were used to pool GTC filter extracts into five samples (4-6 weeks each) dominated by traffic, coal, steel (2 samples), or road salt sources. Five CLM samples were prepared with filter extracts from corresponding weeks. Control non-allergic and house dust mite-allergic Balb/cJ mice were exposed by oropharyngeal aspiration to 100 μg coarse GTC or CLM, control filter extract, or saline only, and responses were examined two days after PM exposures. In allergic mice, exposure to all samples except GTC steel-1, CLM traffic and CLM road salt significantly increased airway responsiveness to methacholine compared with control treatments. All samples except GTC coal, CLM traffic and CLM steel-2 significantly increased bronchoalveolar lavage fluid (BALF) neutrophils in non-allergic mice, while only CLM traffic PM increased eosinophils in allergic mice. In non-allergic mice, CLM coal PM increased interleukin-13 and GTC steel-1 PM increased TNF-α levels in BALF. These results demonstrate that equal masses of GTC and CLM coarse PM enriched with a variety of sources exacerbate allergic airway disease, although greater PM concentrations at the urban GTC site signify a greater potential for human health effects.
URLs/Downloads:
DOI: Source-Apportioned Coarse Particulate Matter Exacerbates Allergic Airway Responses in Mice