title: Exposure to BTEX and Ethers in Petrol Station Attendants and Proposal of Biological Exposure Equivalents for Urinary Benzene and MTBE.
abstract: OBJECTIVE
  To assess exposure to benzene (BEN) and other aromatic compounds (toluene, ethylbenzene, m+p-xylene, o-xylene) (BTEX), methyl tert-butyl ether (MTBE), and ethyl tert-butyl ether (ETBE) in petrol station workers using air sampling and biological monitoring and to propose biological equivalents to occupational limit values.
  
  
  METHODS
  Eighty-nine petrol station workers and 90 control subjects were investigated. Personal exposure to airborne BTEX and ethers was assessed during a mid-week shift; urine samples were collected at the beginning of the work week, prior to and at the end of air sampling.
  
  
  RESULTS
  Petrol station workers had median airborne exposures to benzene and MTBE of 59 and 408 µg m(-3), respectively, with urinary benzene (BEN-U) and MTBE (MTBE-U) of 339 and 780 ng l(-1), respectively. Concentrations in petrol station workers were higher than in control subjects. There were significant positive correlations between airborne exposure and the corresponding biological marker, with Pearson's correlation coefficient (r) values of 0.437 and 0.865 for benzene and MTBE, respectively. There was also a strong correlation between airborne benzene and urinary MTBE (r = 0.835). Multiple linear regression analysis showed that the urinary levels of benzene were influenced by personal airborne exposure, urinary creatinine, and tobacco smoking [determination coefficient (R(2)) 0.572], while MTBE-U was influenced only by personal exposure (R(2) = 0.741).
  
  
  CONCLUSIONS
  BEN-U and MTBE-U are sensitive and specific biomarkers of low occupational exposures. We propose using BEN-U as biomarker of exposure to benzene in nonsmokers and suggest 1457 ng l(-1) in end shift urine samples as biological exposure equivalent to the EU occupational limit value of 1 p.p.m.; for both smokers and nonsmokers, MTBE-U may be proposed as a surrogate biomarker of benzene exposure, with a biological exposure equivalent of 22 µg l(-1) in end shift samples. For MTBE exposure, we suggest the use of MTBE-U with a biological exposure equivalent of 22 µg l(-1) corresponding to the occupational limit value of 50 p.p.m.
authors.affiliation: Department of Clinical Sciences and Community Health, University of Milan and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via S. Barnaba, 8 - 20122 Milan, Italy laura.campo@policlinico.mi.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Campo
authors.affiliation: Department of Clinical Sciences and Community Health, University of Milan and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via S. Barnaba, 8 - 20122 Milan, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Rossella
authors.affiliation: Department of Clinical Sciences and Community Health, University of Milan and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via S. Barnaba, 8 - 20122 Milan, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Mercadante
authors.affiliation: Department of Clinical Sciences and Community Health, University of Milan and Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via S. Barnaba, 8 - 20122 Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Fustinoni
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000032:analysis / Q000652:urine; D001554:Benzene / Q000032:analysis*; D001555:Benzene Derivatives / Q000652:urine*; D015415:Biomarkers / Q000652:urine*; D004784:Environmental Monitoring / Q000379:methods; D005019:Ethyl Ethers / Q000652:urine; D005742:Gasoline; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000652:urine*; D008875:Middle Aged; D016273:Occupational Exposure; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D001555:Benzene Derivatives; D015415:Biomarkers; D005019:Ethyl Ethers; D005742:Gasoline; D008738:Methyl Ethers; C043243:methyl tert-butyl ether; C098546:ethyl tert-butyl ether; D001554:Benzene
keywords: biological exposure equivalent; biological monitoring; biomarkers; exposure assessment; petrol station workers; urinary MTBE; urinary benzene