title: Use of stable isotopically labeled benzene to evaluate environmental exposures.
abstract: The use of stable, isotopically labeled compounds in controlled exposure experiments at environmentally relevant levels allows for the distinguishing of urinary metabolites associated with known exposure from background levels generally present in the urine. Exposures of volunteers to (13)C-benzene for 2 h at 40+/-10 p.p.b. were conducted after obtaining informed consent, and urinary phenol, catechol, hydroquinone and trans,trans- muconic acid were measured. Each isotopically labeled urinary metabolite was determined in the presence of significantly higher concentrations of the unlabeled metabolite. Following exposure, free and acid hydrolyzed phenol, acid hydrolyzed catechol and hydroquinone, and free trans,trans-muconic acid were determined by GC/MS. The percentage of trans,trans-muconic acid excreted was higher than reported following exposure at occupational levels. The use of isotopically labeled compounds has the potential to investigate the metabolism of common environmental contaminants for validation of toxicokinetic models and improve risk extrapolation from high concentration occupational exposures and animal studies to environmentally relevant pollutant levels.
authors.affiliation: Environmental & Occupational Health Sciences Institute and Department of Environmental & Community Medicine, Robert Wood Johnson Medical School/University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, USA. weisel@eohsi.rutgers.edu
authors.forename: Clifford P
authors.initials: CP
authors.lastname: Weisel
authors.forename: Seongsoo
authors.initials: S
authors.lastname: Park
authors.forename: Heesoo
authors.initials: H
authors.lastname: Pyo
authors.forename: Krishnan
authors.initials: K
authors.lastname: Mohan
authors.forename: Gisela
authors.initials: G
authors.lastname: Witz
mesh_terms: D000328:Adult; D001554:Benzene / Q000032:analysis* / Q000493:pharmacokinetics*; D015415:Biomarkers / Q000652:urine; D002247:Carbon Isotopes; D002396:Catechols / Q000652:urine; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006873:Hydroquinones / Q000652:urine; D008297:Male; D008875:Middle Aged; D019800:Phenol / Q000652:urine; D013011:Sorbic Acid / Q000031:analogs & derivatives* / Q000032:analysis
chemical_list: D015415:Biomarkers; D002247:Carbon Isotopes; D002396:Catechols; D006873:Hydroquinones; D019800:Phenol; C005939:muconic acid; D001554:Benzene; C034221:catechol; D013011:Sorbic Acid; C031927:hydroquinone