Benzo[a]pyrene (BaP) metabolites predominant in human plasma following escalating oral micro-dosing with [¹⁴C]-BaP

Journal Article · Wed Dec 15 00:00:00 EST 2021 · Environment International

DOI:https://doi.org/10.1016/j.envint.2021.107045· OSTI ID:1860872

Vermillion Maier, Monics L. ^[1]; Siddens, Lisbeth K. ^[1]; Pennington, Jamie M. ^[1]; Uesugi, Sandra L. ^[1]; Anderson, Kim A. ^[1]; Tidwell, Lane G. ^[1]; Tilton, Susan C. ^[1]; Ognibene, Ted J. ^[2]; Turteltaub, Kenneth W. ^[2]; Smith, Jordan N. ^[3]; Williams, David E. ^[1]

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1. Oregon State Univ., Corvallis, OR (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Oregon State Univ., Corvallis, OR (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Benzo[a]pyrene (BaP) is formed by incomplete combustion of organic materials (petroleum, coal, tobacco, etc.). BaP is designated by the International Agency for Research on Cancer as a group 1 known human carcinogen; a classification supported by numerous studies in preclinical models and epidemiology studies of exposed populations. Risk assessment relies on toxicokinetic and cancer studies in rodents at doses 5–6 orders of magnitude greater than average human uptake. Using a dose–response design at environmentally relevant concentrations, this study follows uptake, metabolism, and elimination of [¹⁴C]-BaP in human plasma by employing UPLC - accelerator mass spectrometry (UPLC-AMS). Volunteers were administered 25, 50, 100, and 250 ng (2.7–27 nCi) of [¹⁴C]-BaP (with interceding minimum 3-week washout periods) with quantification of parent [¹⁴C]-BaP and metabolites in plasma measured over 48 h. [¹⁴C]-BaP median T_max was 30 min with C_max and area under the curve (AUC) approximating dose-dependency. Marked inter-individual variability in plasma pharmacokinetics following a 250 ng dose was seen with 7 volunteers as measured by the C_max (8.99 ± 7.08 ng × mL^-1) and AUC0-48hr (68.6 ± 64.0 fg × hr^-1 × mL^-1). Approximately 3–6% of the [¹⁴C] recovered (AUC_{0-48 hr}) was parent compound, demonstrating extensive metabolism following oral dosing. Metabolite profiles showed that, even at the earliest time-point (30 min), a substantial percentage of [¹⁴C] in plasma was polar BaP metabolites. The best fit modeling approach identified non-compartmental apparent volume of distribution of BaP as significantly increasing as a function of dose (p = 0.004). Bay region tetrols and dihydrodiols predominated, suggesting not only was there extensive first pass metabolism but also potentially bioactivation. AMS enables the study of environmental carcinogens in humans with de minimus risk, allowing for important testing and validation of physiologically based pharmacokinetic models derived from animal data, risk assessment, and the interpretation of data from high-risk occupationally exposed populations.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: National Institute of General Medical Sciences (NIGMS); National Institutes of Health (NIH); USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC05-76RL01830; AC52-07NA27344
• OSTI ID: 1860872
• Alternate ID(s): OSTI ID: 2586786
• Report Number(s): LLNL-JRNL--832614; PNNL-SA--170137; 1050453
• Journal Information: Environment International, Journal Name: Environment International Vol. 159; ISSN 0160-4120
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
Biological and medical sciences
accelerator mass spectrometry
benzo[a]pyrene
human carcinogen dosing
polycyclic aromatic hydrocarbons
toxicokinetics in humans