Excretion kinetics of urinary 3-hydroxybenzo[a]pyrene following dietary exposure to benzo[a]pyrene in humans

Urinary 3-hydroxy-benzo[a]pyrene (3-OHBaP) is considered as an exposure marker for assessing carcinogenic risks as it is a metabolite of benzo[a]pyrene (BaP). A controlled human study was conducted to examine the kinetics of urinary 3-OHBaP after consuming charcoal-barbecued meat. Two feeding experiments were performed, with meat doses of 15 and 30 g/kg (experiments 1 and 2, respectively). All voided urine over 7 days was collected and analyzed. The background urinary 3-OHBaP concentration was 0.002-0.085 ng/g creatinine, with large inter-individual (80-100%) and intra-individual of (90-100%) variations. The background amount of 3-OHBaP excreted by the current subjects was 40-50 pg/day. The amounts of urinary 3-OHBaP excreted within 12 h post-exposure increased significantly (P < 0.05) from background only in experiment 1. The proportion of the administered BaP dose that was excreted as urinary 3-OHBaP within 12 h post-exposure was 0.006 and 0.0012% in experiments 1 and 2, respectively. The excretion ratio declined as the dose increased. Urinary 3-OHBaP can be used to assess dietary exposure to BaP, but it may be not suitable for low-dose scenarios because of the low urinary excretion proportion and high variability of the background.