title: Biomarkers of oxidative stress and its association with the urinary reducing capacity in bus maintenance workers.
abstract: BACKGROUND
  Exposure to particles (PM) induces adverse health effects (cancer, cardiovascular and pulmonary diseases). A key-role in these adverse effects seems to be played by oxidative stress, which is an excess of reactive oxygen species relative to the amount of reducing species (including antioxidants), the first line of defense against reactive oxygen species. The aim of this study was to document the oxidative stress caused by exposure to respirable particles in vivo, and to test whether exposed workers presented changes in their urinary levels for reducing species.
  
  
  METHODS
  Bus depot workers (n = 32) exposed to particles and pollutants (respirable PM4, organic and elemental carbon, particulate metal content, polycyclic aromatic hydrocarbons, NOx, O3) were surveyed over two consecutive days. We collected urine samples before and after each shift, and quantified an oxidative stress biomarker (8-hydroxy-2'-deoxyguanosine), the reducing capacity and a biomarker of PAH exposure (1-hydroxypyrene). We used a linear mixed model to test for associations between the oxidative stress status of the workers and their particle exposure as well as with their urinary level of reducing species.
  
  
  RESULTS
  Workers were exposed to low levels of respirable PM4 (range 25-71 μg/m3). However, urinary levels of 8-hydroxy-2'-deoxyguanosine increased significantly within each shift and between both days for non-smokers. The between-day increase was significantly correlated (p < 0.001) with the concentrations of organic carbon, NOx, and the particulate copper content. The within-shift increase in 8OHdG was highly correlated to an increase of the urinary reducing capacity (Spearman ρ = 0.59, p < 0.0001).
  
  
  CONCLUSIONS
  These findings confirm that exposure to components associated to respirable particulate matter causes a systemic oxidative stress, as measured with the urinary 8OHdG. The strong association observed between urinary 8OHdG with the reducing capacity is suggestive of protective or other mechanisms, including circadian effects. Additional investigations should be performed to understand these observations.
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Sauvain
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.|University of California, Davis; Department of Environmental Toxicology, 4422 Meyer Hall, One Shields Avenue, Davis CA 95616 USA.
authors.forename: Ari
authors.initials: A
authors.lastname: Setyan
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Wild
authors.affiliation: EDEL Therapeutics S.A., PSE-B/EPFL, CH-1015 Lausanne, Switzerland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Tacchini
authors.affiliation: EDEL Therapeutics S.A., PSE-B/EPFL, CH-1015 Lausanne, Switzerland.
authors.forename: Grégoire
authors.initials: G
authors.lastname: Lagger
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Storti
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Deslarzes
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Guillemin
authors.affiliation: Paul Scherrer Institute, Laboratory of Atmospheric Chemistry (LAC), CH-5232 Villigen PSI, Switzerland.
authors.forename: Michel J
authors.initials: MJ
authors.lastname: Rossi
authors.affiliation: Institute for Work and Health, University of Lausanne + Geneva, 21 rue du Bugnon, CH-1011 Lausanne, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Riediker