title: Increased oxidative stress and plasma Hsp70 levels among gasoline filling station attendants.
abstract: OBJECTIVE
  Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) and is used as an antiknock agent and octane enhancer in gasoline. In this article, we tested the oxidative stress and heat stress protein (Hsp) 70 levels of gasoline station attendants to explore potential plasma biomarkers. Furthermore, the dose-response relationship was also identified.
  
  
  METHODS
  A total of 144 workers, including 96 petrol fillers and 48 cashiers, participated in the study. Ambient concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX) and Mn were monitored at nine filling stations. During the measuring process, the individual cumulative exposure index was calculated. Plasma oxidative stress and Hsp70 levels were also analysed using enzyme-linked immunosorbent assay.
  
  
  RESULTS
  The BTEX time-weighted average in office areas was significantly lower than in refuelling areas ( p < 0.05). In refuelling areas, the content of Mn ranged from 6.44 μg/m3to 127.34 μg/m3, which was much higher than that in office areas (3.16-7.22 μg/m3; p < 0.05). Exposed workers had significantly different plasma oxidative stress indicators compared with the control group, respectively: superoxide dismutase (SOD), 39.18 ± 6.05 U/mL versus 52.84 ± 3.87 U/mL; glutathione peroxidase (GSH-Px), 186.07 ± 15.63 U versus 194.38 ± 10.42 U; and malondialdehyde (MDA), 1.68 ± 0.52 nmol/L versus 1.43 ± 0.64 nmol/L (in all comparisons, p < 0.05). Plasma Hsp70 level in the exposed group (2.77 ± 0.64 ng/mL) was significantly higher than in the control group (2.32 ± 0.87 ng/mL; p < 0.05). Furthermore, Hsp70 levels were inversely correlated with the activities of SOD ( r = -0.305) and GSH-Px ( r = -0.302) in the exposed group ( p < 0.05). Moreover, a positive correlation ( r = 0.653) was found between plasma Hsp70 levels and plasma MDA levels ( p < 0.05).
  
  
  CONCLUSIONS
  Exposure to MMT-containing gasoline may result in increasing reactive oxygen stress among filling station attendants. Plasma Hsp70 levels could be used as a sensitive responsive biomarker for exposed workers.
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Xia
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Kangcheng
authors.initials: K
authors.lastname: Chen
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Lv
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Damin
authors.initials: D
authors.lastname: Huang
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: 2 Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Guiqiang
authors.initials: G
authors.lastname: Liang
authors.affiliation: 2 Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Li'e
authors.initials: L
authors.lastname: Zhang
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Fenfen
authors.initials: F
authors.lastname: Wang
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Su
authors.affiliation: 2 Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Zou
authors.affiliation: 1 Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.|3 Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Yang
mesh_terms: D000328:Adult; D004305:Dose-Response Relationship, Drug; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000097:blood*; D006801:Humans; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D018384:Oxidative Stress / Q000187:drug effects*; D010578:Petroleum / Q000009:adverse effects*
chemical_list: D018840:HSP70 Heat-Shock Proteins; D010578:Petroleum
keywords: BTEX; Methylcyclopentadienyl manganese tricarbonyl; heat stress protein 70; manganese; oxidative stress