title: Airway oxidative stress and inflammation markers in exhaled breath from children are linked with exposure to black carbon.
abstract: BACKGROUND
  The current study aimed at assessing the associations between black carbon (BC) exposure and markers for airway inflammation and oxidative stress in primary school children in a Western European urban area.
  
  
  METHODS
  In 130 children aged 6-12 years old, the fraction of exhaled nitric oxide (FeNO), exhaled breath condensate (EBC) pH, 8-isoprostane and interleukin (IL)-1β were measured in two seasons. BC concentrations on the sampling day (2-h average, 8:00-10:00 AM) and on the day before (24-h average) were assessed using measurements at a central monitoring site. Land use regression (LUR) models were applied to estimate weekly average BC exposure integrated for the time spent at home and at school, and seasonal average BC exposure at the home address. Associations between exposure and biomarkers were tested using linear mixed effect regression models. Next to single exposure models, models combining different BC exposure metrics were used.
  
  
  RESULTS
  In single exposure models, an interquartile range (IQR) increase in 2-h BC (3.10 μg/m(3)) was linked with a 5.9% (95% CI: 0.1 to 12.0%) increase in 8-isoprostane. FeNO increased by 16.7% (95% CI: 2.2 to 33.2%) per IQR increase in 24-h average BC (4.50 μg/m(3)) and by 12.1% (95% CI: 2.5 to 22.8%) per IQR increase in weekly BC (1.73 μg/m(3)). IL-1β was associated with weekly and seasonal (IQR=1.70 μg/m(3)) BC with respective changes of 38.4% (95% CI: 9.0 to 75.4%) and 61.8% (95% CI: 3.5 to 153.9%) per IQR increase in BC. An IQR increase in weekly BC was linked with a lowering in EBC pH of 0.05 (95% CI: -0.10 to -0.01). All associations were observed independent of sex, age, allergy status, parental education level and meteorological conditions on the sampling day. Most of the associations remained when different BC exposure metrics were combined in multiple exposure models, after additional correction for sampling period or after exclusion of children with airway allergies. In additional analyses, FeNO was linked with 24-h PM10 levels, but the effect size was smaller than for BC. 8-Isoprostane was not linked with either 2-h or 24-h concentrations of PM2.5 or PM10.
  
  
  CONCLUSIONS
  BC exposure on the morning of sampling was associated with airway oxidative stress while 24-h and weekly exposures were linked with airway inflammation.
authors.affiliation: Environmental Risk and Health Unit, VITO (Flemish Institute for Technological Research), Boeretang 200, B-2400 Mol, Belgium; Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium. Electronic address: sofie.deprins@vito.be.
authors.forename: Sofie
authors.initials: S
authors.lastname: De Prins
authors.affiliation: Environmental Risk and Health Unit, VITO (Flemish Institute for Technological Research), Boeretang 200, B-2400 Mol, Belgium. Electronic address: evi.dons@vito.be.
authors.forename: Evi
authors.initials: E
authors.lastname: Dons
authors.affiliation: Environmental Risk and Health Unit, VITO (Flemish Institute for Technological Research), Boeretang 200, B-2400 Mol, Belgium. Electronic address: martine.vanpoppel@vito.be.
authors.forename: Martine
authors.initials: M
authors.lastname: Van Poppel
authors.affiliation: Environmental Risk and Health Unit, VITO (Flemish Institute for Technological Research), Boeretang 200, B-2400 Mol, Belgium; Transportation Research Institute (IMOB), Hasselt University, Wetenschapspark 5 Bus 6, B-3590 Diepenbeek, Belgium. Electronic address: luc.intpanis@vito.be.
authors.forename: Luc
authors.initials: L
authors.lastname: Int Panis
authors.affiliation: Environment and Health Unit, Provincial Institute of Hygiene, Kronenburgstraat 45, B-2000 Antwerp, Belgium. Electronic address: els.vandemieroop@pih.provant.be.
authors.forename: Els
authors.initials: E
authors.lastname: Van de Mieroop
authors.affiliation: Environment and Health Unit, Provincial Institute of Hygiene, Kronenburgstraat 45, B-2000 Antwerp, Belgium. Electronic address: vera.nelen@pih.provant.be.
authors.forename: Vera
authors.initials: V
authors.lastname: Nelen
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium. Electronic address: bianca.cox@uhasselt.be.
authors.forename: Bianca
authors.initials: B
authors.lastname: Cox
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium. Electronic address: tim.nawrot@uhasselt.be.
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
authors.affiliation: Environment & Health, Flemish Government, Department of Environment, Nature and Energy, Koning Albert II-laan 20 Bus 8, B-1000 Brussels, Belgium. Electronic address: caroline.teughels@lne.vlaanderen.be.
authors.forename: Caroline
authors.initials: C
authors.lastname: Teughels
authors.affiliation: Environmental Risk and Health Unit, VITO (Flemish Institute for Technological Research), Boeretang 200, B-2400 Mol, Belgium; Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium. Electronic address: greet.schoeters@vito.be.
authors.forename: Greet
authors.initials: G
authors.lastname: Schoeters
authors.affiliation: Environmental Risk and Health Unit, VITO (Flemish Institute for Technological Research), Boeretang 200, B-2400 Mol, Belgium. Electronic address: gudrun.koppen@vito.be.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Koppen
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D015237:Dinoprost / Q000031:analogs & derivatives / Q000032:analysis; D004781:Environmental Exposure; D045853:Exhalation; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis; D053583:Interleukin-1beta / Q000032:analysis; D008297:Male; D009569:Nitric Oxide / Q000032:analysis; D018384:Oxidative Stress; D052638:Particulate Matter / Q000032:analysis; D012137:Respiratory System / Q000737:chemistry*; D053260:Soot / Q000032:analysis / Q000633:toxicity*
chemical_list: D000393:Air Pollutants; D015415:Biomarkers; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D052638:Particulate Matter; D053260:Soot; C075750:8-epi-prostaglandin F2alpha; D009569:Nitric Oxide; D015237:Dinoprost
keywords: Air pollution; Airway inflammation; Biomarkers; Children; Exhaled breath condensate; Land use regression