title: Inhalable particulate matter and mitochondrial DNA copy number in highly exposed individuals in Beijing, China: a repeated-measure study.
abstract: BACKGROUND
  Mitochondria are both a sensitive target and a primary source of oxidative stress, a key pathway of air particulate matter (PM)-associated diseases. Mitochondrial DNA copy number (MtDNAcn) is a marker of mitochondrial damage and malfunctioning. We evaluated whether ambient PM exposure affects MtDNAcn in a highly-exposed population in Beijing, China.
  
  
  METHODS
  The Beijing Truck Driver Air Pollution Study was conducted shortly before the 2008 Beijing Olympic Games (June 15-July 27, 2008) and included 60 truck drivers and 60 office workers. Personal PM2.5 and elemental carbon (EC, a tracer of traffic particles) were measured during work hours using portable monitors. Post-work blood samples were obtained on two different days. Ambient PM10 was averaged from 27 monitoring stations in Beijing. Blood MtDNAcn was determined by real-time PCR and examined in association with particle levels using mixed-effect models.
  
  
  RESULTS
  In all participants combined, MtDNAcn was negatively associated with personal EC level measured during work hours (β=-0.059, 95% CI: -0.011; -0.0006, p=0.03); and 5-day (β=-0.017, 95% CI: -0.029;-0.005, p=0.01) and 8-day average ambient PM10 (β=-0.008, 95% CI: -0.043; -0.008, p=0.004) after adjusting for possible confounding factors, including study groups. MtDNAcn was also negatively associated among office workers with EC (β=-0.012, 95% CI: -0.022;-0.002, p=0.02) and 8-day average ambient PM10 (β=-0.030, 95% CI: -0.051;-0.008, p=0.007).
  
  
  CONCLUSIONS
  We observed decreased blood MtDNAcn in association with increased exposure to EC during work hours and recent ambient PM10 exposure. Our results suggest that MtDNAcn may be influenced by particle exposures. Further studies are required to determine the roles of MtDNAcn in the etiology of particle-related diseases.
authors.affiliation: Department of Preventive Medicine Feinberg, School of Medicine Northwestern University, Chicago, IL 60611, USA. l-hou@northwestern.edu
authors.forename: Lifang
authors.initials: L
authors.lastname: Hou
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhang
authors.forename: Laura
authors.initials: L
authors.lastname: Dioni
authors.forename: Francesco
authors.initials: F
authors.lastname: Barretta
authors.forename: Chang
authors.initials: C
authors.lastname: Dou
authors.forename: Yinan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Mirjam
authors.initials: M
authors.lastname: Hoxha
authors.forename: Pier Alberto
authors.initials: PA
authors.lastname: Bertazzi
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Shanshan
authors.initials: S
authors.lastname: Wu
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Baccarelli
mesh_terms: D000328:Adult; D000397:Air Pollution; D001336:Automobiles; D002681:China; D056915:DNA Copy Number Variations; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000097:blood / Q000187:drug effects*; D004784:Environmental Monitoring; D005260:Female; D018628:Gene Dosage; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D008297:Male; D015999:Multivariate Analysis; D018384:Oxidative Stress / Q000187:drug effects*; D052638:Particulate Matter / Q000009:adverse effects*; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors; D001335:Vehicle Emissions / Q000633:toxicity*; D055815:Young Adult
chemical_list: D004272:DNA, Mitochondrial; D052638:Particulate Matter; D001335:Vehicle Emissions