title: Comparative toxicity of size-fractionated airborne particulate matter collected at different distances from an urban highway.
abstract: BACKGROUND
  Epidemiologic studies have reported an association between proximity to highway traffic and increased cardiopulmonary illnesses.
  
  
  OBJECTIVE
  We investigated the effect of size-fractionated particulate matter (PM), obtained at different distances from a highway, on acute cardiopulmonary toxicity in mice.
  
  
  METHODS
  We collected PM for 2 weeks in July-August 2006 using a three-stage (ultrafine, < 0.1 microm; fine, 0.1-2.5 microm; coarse, 2.5-10 microm) high-volume impactor at distances of 20 m [near road (NR)] and 275 m [far road (FR)] from an interstate highway in Raleigh, North Carolina. Samples were extracted in methanol, dried, diluted in saline, and then analyzed for chemical constituents. Female CD-1 mice received either 25 or 100 microg of each size fraction via oropharyngeal aspiration. At 4 and 18 hr postexposure, mice were assessed for pulmonary responsiveness to inhaled methacholine, biomarkers of lung injury and inflammation; ex vivo cardiac pathophysiology was assessed at 18 hr only.
  
  
  RESULTS
  Overall chemical composition between NR and FR PM was similar, although NR samples comprised larger amounts of PM, endotoxin, and certain metals than did the FR samples. Each PM size fraction showed differences in ratios of major chemical classes. Both NR and FR coarse PM produced significant pulmonary inflammation irrespective of distance, whereas both NR and FR ultrafine PM induced cardiac ischemia-reperfusion injury.
  
  
  CONCLUSIONS
  On a comparative mass basis, the coarse and ultrafine PM affected the lung and heart, respectively. We observed no significant differences in the overall toxicity end points and chemical makeup between the NR and FR PM. The results suggest that PM of different size-specific chemistry might be associated with different toxicologic mechanisms in cardiac and pulmonary tissues.
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Cho
authors.forename: Haiyan
authors.initials: H
authors.lastname: Tong
authors.forename: John K
authors.initials: JK
authors.lastname: McGee
authors.forename: Richard W
authors.initials: RW
authors.lastname: Baldauf
authors.forename: Q Todd
authors.initials: QT
authors.lastname: Krantz
authors.forename: M Ian
authors.initials: MI
authors.lastname: Gilmour
mesh_terms: D055371:Acute Lung Injury / Q000139:chemically induced / Q000503:physiopathology; D000393:Air Pollutants / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004731:Endotoxins / Q000737:chemistry / Q000633:toxicity; D005260:Female; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology; D019570:Inhalation Exposure / Q000009:adverse effects*; D008670:Metals / Q000737:chemistry / Q000633:toxicity; D051379:Mice; D015428:Myocardial Reperfusion Injury / Q000139:chemically induced / Q000503:physiopathology; D009657:North Carolina; D010316:Particle Size; D052638:Particulate Matter / Q000737:chemistry / Q000633:toxicity*; D013997:Time Factors; D001335:Vehicle Emissions / Q000633:toxicity
chemical_list: D000393:Air Pollutants; D015415:Biomarkers; D004731:Endotoxins; D008670:Metals; D052638:Particulate Matter; D001335:Vehicle Emissions