Multicompartmental Toxicokinetic Modeling of Discrete Dietary and Continuous Waterborne Uptake of Two Polycyclic Aromatic Hydrocarbons by Zebrafish Danio rerio

In the present study, we developed a multicompartmental toxicokinetic model for two polycyclic aromatic hydrocarbons (phenanthrene and anthracene) in their deuterated form (PAHs-d(10)) in zebrafish considering continuous waterborne uptake and discrete dietary uptake. We quantified the bioconcentration, bioaccumulation, and depuration of these two PAHs-d(10) in zebrafish, and then estimated the kinetic parameters by fitting the model into the experimental data. The experimental and fitting results both showed that there was a peak concentration in each compartment of zebrafish after every dietary uptake, while the peak value depended on the ingestion amount of the PAH-d(10) and varied among different compartments. The PAH-d(10) amount in the blood reached 20-27% of the total amount bioaccumulated in zebrafish at steadystate, followed by skin (20-26%), and fillet (16-22%). The rank of PAH-d(10) steady-state concentrations in each compartment showed inconsistency with its lipid contents, indicating that the distribution of the PAHs-d(10) in zebrafish was not merely affected by the lipid content in each compartment, but also affected by their kinetics and biotransformation. This study suggests that discrete dietary uptake caused by intermittent food ingestion significantly affects the bioaccumulation of PAHs in fish. Further studies are needed to investigate such effect on other toxicants that are more resistant to biotransformation than PAHs in fish.