Urinary Benzo[a]pyrene and Its Metabolites as Molecular Biomarkers of Asphalt Fume Exposure Characterized by Microflow LC Coupled to Hybrid Quadrupole Time-of-Flight Mass Spectrometry

As a step to study the health effects of asphalt fume exposure, an analytical method was developed to characterize benzo[a] pyrene and its hydroxy metabolites in the urine of asphalt fume-exposed rats. This method is based on microflow liquid chromatography (LC) coupled to hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry (Q-TOFMS). Twenty-four female Sprague-Dawley rats were used in the experiment, with 8 as controls and 16 exposed to asphalt fumes in a whole-body inhalation chamber for 10 days (4 h/day). Generated at 150 (degree)C, the asphalt fume concentration in the animal exposure chamber ranged 76-117 mg/m3. In the urine of the asphalt fume-exposed rats, benzo[a]pyrene and its metabolites of 3-hydroxybenzo[a]pyrene, benzo[a]pyrene-7,8-dihydrodiol(+-), and benzo[a]pyrene-7,8,9,10tetrahydrotetrol(+-) were identified, and their concentrations were determined at 2.19 +- 0.49, 16.17 +- 0.3, 6.28 +- 0.36, and 29.35 +- 0.26 ng/100 mL, respectively. The metabolite concentrations from the controlled group, however, were either under the detection limits or at a relatively very low level (0.19 +- 0.41 ng/100 mL for benzo[a]pyrene-7,8,9,10tetrahydrotetrol metabolite). The results clearly indicate that the benzo[a]pyrene and its hydroxy metabolites were significantly elevated (p < 0.001) in the urine of asphalt fume-exposed rats relative to controls. The study also demonstrated that the combination of microflow LC separation and collision-induced dissociation le