Identification and quantification of 1-nitropyrene metabolites in human urine as a proposed biomarker for exposure to diesel exhaust.
1-nitropyrene (1-NP) is one of the most abundant nitrated polycyclic aromatic hydrocarbons (NPAHs) in diesel exhaust particulate matter (DEP) and is a main contributor of direct-acting mutagenicity in DEP. Therefore, the metabolites of 1-NP are expected to be a biomarker for assessment of exposure to DEP. In this study, a highly specific and sensitive analytical method using liquid chromatography with tandem mass spectrometry (LC-MS/MS) was developed to determine urinary 1-NP metabolites. After enzymatic hydrolysis of the conjugated metabolites, the analytes were selectively extracted from the urine matrix with blue rayon. The eluate from the rayon was further purified on an acidic alumina cartridge. Hydroxy-N-acetyl- 1-aminopyrenes (6- and 8-OHNAAP) and hydroxy-1-nitropyrenes (3-, 6-, and 8-OHNP) in human urine were identified by their retention times and MS/MS spectra and quantified by using deuterated internal standards. 1-NP metabolites were quantified in urine from all healthy, nonoccupationally exposed subjects. 6-OHNAAP, 8-OHNAAP, 6-OHNP, and 8-OHNP (means of 117, 109, 203, and 137 pmol/mol creatinine, respectively) were the most abundant isomers in human urine. This report is the first to demonstrate the presence of OHNAAPs and OHNPs in human urine, in agreement with previous in vivo and in vitro studies that predicted that these metabolites should be excreted into human urine. This method for determining urinary 1-NP metabolites should be useful for the surveillance of exposure to NPAHs and DEP and will facilitate the study of cancer risk associated with these exposures.
Toriba
Akira
A
Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan. toriba@p.kanazawa-u.ac.jp
Kitaoka
Hitomi
H
Dills
Russell L
RL
Mizukami
Satoko
S
Tanabe
Kaori
K
Takeuchi
Naoki
N
Ueno
Mariko
M
Kameda
Takayuki
T
Tang
Ning
N
Hayakawa
Kazuichi
K
Simpson
Christopher D
CD
D000328:Adult; D000397:Air Pollution / Q000032:analysis; D015415:Biomarkers / Q000652:urine*; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011721:Pyrenes / Q000032:analysis* / Q000378:metabolism; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods; D001335:Vehicle Emissions / Q000032:analysis*
D015415:Biomarkers; D011721:Pyrenes; D001335:Vehicle Emissions; C033146:1-hydroxypyrene; C032668:1-nitropyrene