title: Cytotoxic and inflammatory potential of size-fractionated particulate matter collected repeatedly within a small urban area.
abstract: BACKGROUND
  Exposure to coarse, fine, and ultrafine particles is associated with adverse population health impacts. We investigated whether size-fractionated particles collected repeatedly in the vicinity of industrial (steel mills and associated coking operations, wastewater treatment), high traffic, and residential areas display systematic differences in biological potency.
  
  
  METHODS
  Particulate matter (PM<0.1, PM0.1-0.5, PM0.5-2.5, PM2.5-10, PM>10) samples collected at sites within Windsor, Ontario, were screened for biological potency in human A549 lung epithelial and murine J774A.1 macrophage-like cells using cytotoxicity bioassays (cellular ATP, resazurin reduction, lactate dehydrogenase (LDH) release), cytokine production, and transcript profiles. Potency was determined from the slope of each dose-effect relationship.
  
  
  RESULTS
  Cytotoxic potency varied across size fractions and within a fraction across sites and sampling periods, suggesting that particle composition, in addition to size and mass, affected particle toxicity. While ATP and LDH profiles showed some similarity, resazurin reduction (a measure of metabolic activity) exhibited a unique pattern of response, indicating that the cytotoxicity assays were sensitive to distinct particle characteristics. Chemical speciation varied in relation to prevailing winds, consistent with enrichment of source emissions (e.g. higher metal and polycyclic aromatic hydrocarbon content downwind of the industrial site). Notwithstanding this variability, site-dependent differences in particle toxicity were evident, including greater potency of coarse fractions at the industrial site and of ultrafine particles at the traffic site (Site × Size interactions, p < 0.05). Regression of potency against particle constituents revealed correlations between resazurin reduction, induction of metal-responsive genes, and metal content, which were particularly strong for the coarse fraction, and between cytokine release and endotoxin, suggesting that these factors were important drivers of biological effects that explain, at least in part, the contrasting potencies of particles compared on an equivalent mass basis.
  
  
  CONCLUSIONS
  The data show that 1) particle potency and composition can exhibit significant temporal variation in relation to source contributions; 2) sources may differentially impact the potency of specific size fractions; and 3) particle constituents, notably metals and endotoxin, may elicit distinct biological responses. Together, the data are consistent with the notion that sources and composition, in addition to size and mass concentration, are relevant to particle toxicity.
authors.affiliation: Inhalation Toxicology Laboratory, Hazard Identification Division, Environmental Health Science and Research Bureau, Health Canada, 0802B Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada. errol.thomson@hc-sc.gc.ca.
authors.forename: Errol M
authors.initials: EM
authors.lastname: Thomson
authors.affiliation: Inhalation Toxicology Laboratory, Hazard Identification Division, Environmental Health Science and Research Bureau, Health Canada, 0802B Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada. dalibor.breznan@hc-sc.gc.ca.
authors.forename: Dalibor
authors.initials: D
authors.lastname: Breznan
authors.affiliation: Inhalation Toxicology Laboratory, Hazard Identification Division, Environmental Health Science and Research Bureau, Health Canada, 0802B Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada. subramanian.karthikeyan@hc-sc.gc.ca.
authors.forename: Subramanian
authors.initials: S
authors.lastname: Karthikeyan
authors.affiliation: Inhalation Toxicology Laboratory, Hazard Identification Division, Environmental Health Science and Research Bureau, Health Canada, 0802B Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada. christine.mackinnon-roy@cihr-irsc.gc.ca.
authors.forename: Christine
authors.initials: C
authors.lastname: MacKinnon-Roy
authors.affiliation: Analysis and Air Quality Section, Air Quality Research Division, Atmospheric Science and Technology Directorate, Environment Canada, Ottawa, ON, K1A 0H3, Canada. jean-pierre.charland@ec.gc.ca.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Charland
authors.affiliation: Analysis and Air Quality Section, Air Quality Research Division, Atmospheric Science and Technology Directorate, Environment Canada, Ottawa, ON, K1A 0H3, Canada. ewa.dabek@ec.gc.ca.
authors.forename: Ewa
authors.initials: E
authors.lastname: Dabek-Zlotorzynska
authors.affiliation: Analysis and Air Quality Section, Air Quality Research Division, Atmospheric Science and Technology Directorate, Environment Canada, Ottawa, ON, K1A 0H3, Canada. valbona.celo@ec.gc.ca.
authors.forename: Valbona
authors.initials: V
authors.lastname: Celo
authors.affiliation: Mechanistic Studies Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, K1A 0K9, Canada. premkumari.kumarathasan@hc-sc.gc.ca.
authors.forename: Prem
authors.initials: P
authors.lastname: Kumarathasan
authors.affiliation: Air Quality Processes Research Section, Air Quality Research Division, Atmospheric Science and Technology Directorate, Environment Canada, Toronto, ON, M3H 5T4, Canada. jeff.brook@ec.gc.ca.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Brook
authors.affiliation: Inhalation Toxicology Laboratory, Hazard Identification Division, Environmental Health Science and Research Bureau, Health Canada, 0802B Tunney's Pasture, Ottawa, ON, K1A 0K9, Canada. renaud.vincent@hc-sc.gc.ca.
authors.forename: Renaud
authors.initials: R
authors.lastname: Vincent
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D016207:Cytokines / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods*; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D007220:Industrial Waste / Q000009:adverse effects*; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism; D019570:Inhalation Exposure; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008168:Lung / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D051379:Mice; D009864:Ontario; D010084:Oxidation-Reduction; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*; D011014:Pneumonia / Q000139:chemically induced* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018570:Risk Assessment; D014504:Urban Health; D001335:Vehicle Emissions / Q000633:toxicity*; D014919:Wind
chemical_list: D016207:Cytokines; D007220:Industrial Waste; D018836:Inflammation Mediators; D052638:Particulate Matter; D001335:Vehicle Emissions; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase