title: A comparative assessment of liver function in workers in the petroleum industry.
abstract: OBJECTIVE
  The group studied included 666 workers from the benzene (n = 30), xylenes (n = 144), ethylene oxide (n = 91), 1,3-butadiene (n = 110) and transport and mechanisation (n = 82) departments of a petrochemical plant in Bulgaria. The leading hazards for the particular departments are as follows: Benzene: benzene (up to ten times the threshold limit value; TLV): xylenes: benzene (up to nine times TLV) and xylenes (up to 1.6 times TLV); ethylene oxide: ethylene oxide (up to 20 times TLV) and ethylene (up to 30 times TLV); divinyl: 1,3-butadiene (five times TLV) and acetonitrile (six times TLV); transport and mechanisation: benzene, xylenes and pentane (0.7-10 times TLV).
  
  
  METHODS
  The functional status of the liver was assessed by clinical (medical check-up), echographic and biochemical (ASAT, ALAT, APh, gamma-GT, lipid fractions, reduced glutathione and SH groups) investigations. Biochemical analyses were performed with POINTE 190 (USA). The results obtained were compared with those of a control group (n = 150), consisting of subjects with no occupational exposure to chemical hazards.
  
  
  RESULTS
  Comparisons showed that the metabolic disturbances determined were most significant in workers from the ethylene oxide department. Significant decreases in the serum levels of reduced glutathione (up to 48%) and of thiol groups (with 23%), increased enyzme activity (up to 18%) and lipid fractions (up to 24%) were observed. In the benzene and xylenes departments, deviations in the indices studied were equally manifest. In workers exposed to 1,3-butadiene, the changes in lipid indices were prevalent (registered in 25% of the studied persons). The staff in transport and mechanisation showed deviations in enzyme indices at a slight increase of the lipid fractions. The changes determined in serum biochemical characteristics corresponded to the clinical findings--hepatomegaly, confirmed echographically in 10%-20% in the different departments.
  
  
  CONCLUSIONS
  The results obtained followed the exposure-response relationship. The deviations registered in workers with a length of service of more than 10 years were the most significant. The occupational genesis of the determined disturbances was confirmed in 11 subjects.
authors.affiliation: National Centre of Hygiene, Medical Ecology and Nutrition, Sofia, Bulgaria. popov@mgu.bg
authors.forename: A
authors.initials: A
authors.lastname: Michailova
authors.forename: T
authors.initials: T
authors.lastname: Kuneva
authors.forename: T
authors.initials: T
authors.lastname: Popov
mesh_terms: D000328:Adult; D019652:Extraction and Processing Industry; D005260:Female; D006801:Humans; D008099:Liver / Q000502:physiology*; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D010578:Petroleum
chemical_list: D010578:Petroleum