title: Possibilities to control the health risk of petrochemical workers.
abstract: OBJECTIVE
  It is well known that the adverse health effects of a number of chemical substances are related to the formation of free radicals. The aim of this study was to assess the degree of oxidative stress and the possibility of strengthening the antioxidative potential of the organism by antioxidant treatment.
  
  
  METHODS
  The levels of benzene, toluene, xylene, hexane, ethylbenzene and total hydrocarbons were measured in workplace air by personal dosimetry. A questionnaire was used to collect data on length of service, past and current occupational exposure to chemicals, lifestyle, diet, past and current diseases, drug use. The antioxidative status was measured by indices: malondialdehyde (MDA) and reduced glutathione (GSH); glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity; total antioxidant status (TAS), levels of alpha-tocopherol and vitamin A; selenium, before and after the treatment. The workers were given tablets containing vitamins, micro-elements, and bioflavonoids, in appropriate doses. All subjects had signed an informed consent.
  
  
  RESULTS
  Before treatment the workers had significantly higher MDA levels ( P<0.001) and lower GSH concentrations ( P<0.001) and GPx activities ( P<0.001) than did the controls. Other indices were without significant changes. The results after 40 days of supplementation demonstrated that the number of subjects with high values of MDA decreased significantly; the activity of GPx was within the referent values; the level of GSH had also recovered and conformed to physiological norms.
  
  
  CONCLUSIONS
  The decrease of GPx and GSH and the increase of the MDA levels give evidence of misbalance in the antioxidant status. The decreased values of MDA and the increased GPx activity and GSH concentrations at the second examination proved the positive effect of the treatment. The strengthened antioxidant potential of workers exposed to a mixture of hydrocarbons confirmed the possibilities that the exposure-related health risk can be controlled and the adverse effects prevented.
authors.affiliation: Department of Toxicology, National Center of Hygiene, Medical Ecology and Nutrition, 15D Nestorov Boulevard, 1431 Sofia, Bulgaria. tzvege@dir.bg
authors.forename: Tzveta
authors.initials: T
authors.lastname: Georgieva
authors.forename: Anna
authors.initials: A
authors.lastname: Michailova
authors.forename: Teodor
authors.initials: T
authors.lastname: Panev
authors.forename: Todor
authors.initials: T
authors.lastname: Popov
mesh_terms: D000328:Adult; D002617:Chemical Industry; D005260:Female; D005978:Glutathione / Q000032:analysis*; D005979:Glutathione Peroxidase / Q000032:analysis* / Q000494:pharmacology; D006306:Health Surveys; D006801:Humans; D006838:Hydrocarbons / Q000009:adverse effects*; D008297:Male; D008315:Malondialdehyde / Q000032:analysis* / Q000494:pharmacology; D008875:Middle Aged; D016273:Occupational Exposure / Q000517:prevention & control; D018384:Oxidative Stress; D010578:Petroleum / Q000009:adverse effects*; D018570:Risk Assessment; D017132:Workplace
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D008315:Malondialdehyde; D005979:Glutathione Peroxidase; D005978:Glutathione