title: Exposure to benzene induces oxidative stress, alters the immune response and expression of p53 in gasoline filling workers.
abstract: BACKGROUND
  Chronic exposure to benzene can lead to deleterious effects on many biological systems including blood and blood-forming organs. We investigated the adverse effects of benzene among workers occupationally exposed to benzene in India.
  
  
  METHODS
  Four hundred twenty-eight gasoline filling workers occupationally exposed to benzene and 78 unexposed individuals were recruited for this study. Benzene concentration was determined by gas chromatography, reactive oxygen species (ROS) by dichlorofluorescin diacetate (DCFH-DA) method, malondialdehyde (MDA) by thiobarbituric acid reactive substances assay (TBARS), total superoxide dismutase (T-SOD) by RANSOD kit and glutathione (GSH) by 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) reaction, respectively. CD4, CD8, IgG were carried out by using fluorescence activated cell sorter (FACS Calibur) and mRNA expression of p53 by reverse transcriptase PCR (RT-PCR).
  
  
  RESULTS
  A significant increase in the concentration of benzene and its byproducts in both blood and urine were found in the workers compared with the controls. The levels of ROS and MDA were significantly elevated, and GSH and total T-SOD were decreased in the workers compared with the controls. A statistically significant decrease in the immunoglobulin levels, CD4T cells, CD4/CD8 ratio was observed in workers (vs. controls), whereas no significant difference was observed in CD8T cells. p53 gene expression was markedly higher in workers than in controls.
  
  
  CONCLUSIONS
  Occupational exposure to benzene causes oxidative stress, immune suppression and increases the expression of tumor-suppressing gene p53 in gasoline filling workers. These bio-functional markers might be useful in screening and surveillance for occupational hazard.
authors.affiliation: Department of Physiology, Deccan College of Medical Sciences, Hyderabad 500 058, Andhra Pradesh, India.
authors.forename: Nazia
authors.initials: N
authors.lastname: Uzma
authors.forename: B Santhosh
authors.initials: BS
authors.lastname: Kumar
authors.forename: Mohammed Abdul Hannan
authors.initials: MA
authors.lastname: Hazari
mesh_terms: D000328:Adult; D001554:Benzene / Q000633:toxicity*; D015704:CD4 Antigens / Q000187:drug effects / Q000276:immunology; D005260:Female; D005742:Gasoline / Q000633:toxicity*; D016158:Genes, p53 / Q000187:drug effects / Q000235:genetics; D005978:Glutathione / Q000187:drug effects; D006801:Humans; D007107:Immune System / Q000187:drug effects*; D007074:Immunoglobulin G / Q000187:drug effects / Q000276:immunology; D007136:Immunoglobulins / Q000187:drug effects; D008297:Male; D008315:Malondialdehyde / Q000633:toxicity*; D016273:Occupational Exposure / Q000009:adverse effects*; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000187:drug effects; D017382:Reactive Oxygen Species; D011948:Receptors, Antigen, T-Cell / Q000187:drug effects; D013223:Statistics as Topic; D013482:Superoxide Dismutase / Q000187:drug effects
chemical_list: D015704:CD4 Antigens; C067361:CD8 receptor; D005742:Gasoline; D007074:Immunoglobulin G; D007136:Immunoglobulins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D011948:Receptors, Antigen, T-Cell; D008315:Malondialdehyde; D013482:Superoxide Dismutase; D005978:Glutathione; D001554:Benzene