title: Correlation between environmental and biological monitoring of exposure to benzene in petrochemical industry operators.
abstract: The present work was aimed to study in petrochemical industry operators the correlation, if any, between environmental exposure to low levels of benzene and two biological exposure indexes in end-shift urine, i.e. trans, trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (SPMA). Exposure to benzene was assessed in 133 male subjects employed in outdoor operations in a petrochemical plant, using personal passive-diffusive air samplers worn at the breathing zone; adsorbed benzene was determined by GC-FID analysis. S-PMA was determined by a new HPLCMS/MS method, after (quantitative) acidic hydrolysis of the cysteine conjugate precursor. t,t-MA was measured by an HPLC-UV method. Smoking habits were assessed by means of a self-administered questionnaire. Both environmental and biological monitoring data showed that benzene exposure of petrochemical industry operators was low (mean values were 0.014ppm, 101mug/g creat, and 2.8mug/g creat, for benzene, t,t-MA, and S-PMA, respectively) if compared with the ACGIH limits. Cigarette smoking was confirmed to be a strong confounding factor for the urinary excretion of both metabolites: statistically significant increases of t,t-MA and S-PMA levels were recorded in smokers when compared to non-smokers (p<0.0001). The best correlation found was that between exposure to benzene and S-PMA levels, particularly in non-smokers. This was partly due to the hydrolysis of the S-PMA precursor N-acetyl-S-(1,2-dihydro-2-hydroxyphenyl)-l-cysteine, a crucial step of the new analytical method used, which indeed reduced the variability of the results by means of an improved standardization of this critical preanalytical factor. A weaker correlation was found between exposure to benzene and t,t-MA, possibly explained by the fact that the latter is also a metabolite of sorbic acid, a common diet component. In summary, even at such low levels of exposure, urinary metabolites proved to be a useful tool for assessing individual occupational exposure to benzene, S-PMA appearing to be a more specific biomarker than t,t-MA, particularly in non-smokers.
authors.affiliation: Department of Environmental Medicine and Public Health, University of Padua, Padua 35128, Italy. mariella.carrieri@unipd.it
authors.forename: Mariella
authors.initials: M
authors.lastname: Carrieri
authors.forename: Giovanna
authors.initials: G
authors.lastname: Tranfo
authors.forename: Daniela
authors.initials: D
authors.lastname: Pigini
authors.forename: Enrico
authors.initials: E
authors.lastname: Paci
authors.forename: Fabiola
authors.initials: F
authors.lastname: Salamon
authors.forename: Maria L
authors.initials: ML
authors.lastname: Scapellato
authors.forename: Maria E
authors.initials: ME
authors.lastname: Fracasso
authors.forename: Maurizio
authors.initials: M
authors.lastname: Manno
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Bartolucci
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000652:urine; D001554:Benzene / Q000032:analysis* / Q000493:pharmacokinetics; D015415:Biomarkers / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007221:Industry; D008297:Male; D016273:Occupational Exposure / Q000032:analysis*; D010578:Petroleum; D052616:Solid Phase Extraction; D013011:Sorbic Acid / Q000031:analogs & derivatives / Q000032:analysis; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D010578:Petroleum; C005939:muconic acid; C053003:S-phenyl-N-acetylcysteine; D001554:Benzene; D000111:Acetylcysteine; D013011:Sorbic Acid