Full length articleAssociations between polycyclic aromatic hydrocarbon (PAH) exposure and oxidative stress in people living near e-waste recycling facilities in China
Graphical abstract
Introduction
Electronic waste (e-waste) recycling has received considerable attention globally because of its ensuing environmental health hazards. It was reported that approximately 40 million tons of e-wastes have been generated per year globally (Huisman et al., 2008). At present, approximately 70% of the e-waste generated worldwide is processed in China every year (i.e., 28 million tons yr− 1) (Zhang et al., 2012). E-waste contains toxic organic pollutants and metals; thus, these chemicals may travel around the globe and have adverse effects, far away from the locations of their production and initial use through international e-waste trade (Breivik et al., 2016).
The incomplete combustion of e-waste can cause the continuous emission of polycyclic aromatic hydrocarbons (PAHs) (Yu et al., 2006, Wang et al., 2012, Huang et al., 2014, Luo et al., 2015); besides, coal burning for the melting of circuit boards can release PAHs (Yu et al., 2006, Fan et al., 2014). Previous studies have demonstrated that elevated levels of PAHs exist in environmental matrices (e.g., soil, sediment and air) near e-waste dismantling sites (Yu et al., 2006, Wang et al., 2012, Huang et al., 2014, Luo et al., 2015). Concentrations of PAHs in soil samples collected from e-waste recycling sites (2340 ng/g) or dismantling areas (678 ng/g) were one to two orders of magnitude higher than those in soil from reference areas (77 ng/g) (Yu et al., 2006). Atmospheric particulate PAHs levels in e-waste recycling areas were significantly higher (p < 0.05) than those in urban reference areas (Luo et al., 2015). E-waste dismantling workers and people living near e-waste recycling sites were shown to have significantly elevated risks of developing cancer and cardiovascular diseases (Guo et al., 2012, Wang et al., 2012).
Although earlier studies have reported PAHs in environmental matrices in and around e-waste recycling areas, little is known on human exposure to PAHs in these sites. Urinary levels of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) are widely used as biomarker of PAH exposure (Guo et al., 2013, Gong et al., 2015, Thai et al., 2016). There are only few studies investigated urinary OH-PAH levels in participants living near an e-waste recycling area (Wang et al., 2014, Yang et al., 2015). Wang et al. (2014) found that the concentrations of 2-hydroxynaphthalene (2-NAP), 2-hydoxyfluorene (2-FLUO), 9-hydroxyphenanthrene (9-PHEN), and 1-hydroxypyrene (1-PYR) are significantly (p < 0.05) higher in participants living in e-waste site (n = 41) than in participants living in control area (n = 45). Nevertheless, the earlier study (Wang et al., 2014) used a small sample size; and high performance liquid chromatography (HPLC) with fluorescence detection [limit of detection (LOD): 44.0 to 1620 ng/mL], which was not as sensitive and selective as the mass spectrometric method.
Toxicological studies have shown that PAH metabolites can go through redox cycling and generate reactive oxygen species (ROS) (Palackal et al., 2002). The ROS can then elicit oxidative modification of DNA and lipids in the human body (Palackal et al., 2002). As one of the predominant forms of oxidative lesions in DNA, 8-hydroxy-2′-deoxyguanosine (8-OHdG) is a critical biomarker for oxidative DNA damage (Musarrat et al., 1996, Chiou et al., 2003). Malondialdehyde (MDA) is a reliable biomarker of lipid peroxidation (Sezer et al., 2012). Determination of 8-OHdG and MDA can be used to evaluate overall oxidation status in human bodies. Yang et al. (2015) observed elevated levels of urinary 8-OHdG in e-waste recycling area (n = 62) which indicating that exposure to e-waste-related pollutants (e.g., PAHs) could increase the occurrence of oxidative stress. However, the associations between PAH exposure and oxidative stress are still unclear in e-waste recycling site.
In this study, we therefore investigated human exposure to PAHs in e-waste dismantling locations and examined the association between PAH exposure and oxidative stress by measuring ten OH-PAHs, 8-OHdG and MDA in urine samples collected from participants living in one of the three largest e-waste recycling locations in China.
Section snippets
Sample collection
During July 2014, first-morning void (fasting time: > 8 h) urine samples were collected from volunteer participants in an e-waste recycling area located in Longtang Town, Qingyuan City, using 50-mL polypropylene (PP) tube. A detailed description of the sampling site has been provided elsewhere (Chen et al., 2014, Zhang et al., 2016). The study was approved by the Institutional Review Board of Sun Yat-sen University, China. All the participants consented for the participation; consent from
Results and discussion
Urinary concentrations [geometric mean (GM), median, minimum and maximum] of 10 target OH-PAHs, 8-OHdG and MDA in residents and workers from e-waste dismantling site and two reference sites are shown in Table 1.
Conclusions
In summary, elevated urinary ∑10OH-PAHs levels were found in participants living in the e-waste recycling areas. Besides, the levels of urinary 8-OHdG significantly increased with increasing urinary ∑10OH-PAHs or individual OH-PAHs; the levels of urinary MDA were significantly positively correlated with 1-PYR (r = 0.284) in the e-waste recycling area; these findings indicated that PAH exposure are associated with oxidative stress. Nevertheless, this is a cross-sectional design study, and the
Acknowledgments
The Natural Science Foundation of China (no. 41225004 and no. 41303094), Guangdong Provincial Natural Science Foundation (no. 2016A030306033) and Pear River S&T Nova Program of Guangzhou are acknowledged for their partial research supports. A part of this study (analysis was performed at Wadsworth Center) was funded by a grant (1U38EH000464-01) from the US CDC (Atlanta, GA) to Wadsworth Center, New York State Department of Health. Its contents are solely the responsibility of the authors and do
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