Biomarkers of oxidative stress and its association with the urinary reducing capacity in bus maintenance workers

Abstract

BackgroundExposure 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.MethodsBus 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.ResultsWorkers 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).ConclusionsThese 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.

Association between Urinary 8-Hydroxydeoxyguanosine, an Indicator of Oxidative Stress, and the Cardio-Ankle Vascular Index in Hypertensive Patients

“…This is in agreement with numerous previous reports studied in smokers 11,12) or bus depot workers, who were exposed to respirable particles and pollutants 27) ; however, our cross-sectional study can add new information by showing a significant association between the urinary 8-OHdG level and the CAVI as an indicator of arteriosclerosis in hypertensive patients. As CAVI has been demonstrated to be high in smoking subjects 24) , the smoking status also differed in the comparison between groups with normal and elevated CAVI in the present study (Table 4); therefore, we examined the relationship between urinary 8-OHdG and CAVI in 87 non-smokers in the present study.…”

Public health and components of particulate matter: The changing assessment of black carbon

“…For example, Sauvain et al (2011) found that oxidative stress levels in workers at a bus depot were elevated after a workday, compared to before work, and were more highly elevated at the end of a second consecutive workday than after the first workday. Relative to the general U.S. population, workers in the trucking industry most consistently exposed to higher levels of diesel exhaust (drivers and dock workers) had significantly elevated rates of both lung cancer and ischemic heart disease (Laden et al, 2007), while those with less exposure (hostlers and clerks) did not.…”

8-Hydroxydeoxyguanosine as a Useful Marker for Determining the Severity of Trichloroethylene Exposure

“…Once produced, 8-OHdG is very stable and is not further metabolized in the systemic circulation. 19 Another advantage of this marker is that it is affected by neither diet nor cell turnover. 8 Due to these unique properties, 8-OH-dG is an ideal biomarker for determining the severity of DNA damage and oxidative stress.…”

“…21 Sauvain et al and Wang et al suggested urinary 8-OH-dG as an oxidative stress indicator in kitchen workers of Chinese restaurants and bus maintenance workers, respectively. 19,22 Pan et al revealed that kitchen workers' urinary 8-OH-dG levels are higher than service staff. 23 In our study, we found that urinary creatinine adjusted 8-OH-dG levels are higher in TCE-exposed group compared with control group (p < .001).…”