Bioaccumulation, Biotransformation, and Multicompartmental Toxicokinetic Model of Antibiotics in Sea Cucumber (Apostichopus japonicus)

Abstract

Extensive application of antibiotics leads to their ubiquitous occurrence in coastal aquatic environments. However, it remains largely unknown whether antibiotics can be bioaccumulated and biotransformed in major mariculture organisms such as sea cucumbers and toxicokinetic models for Echinodermata are lacking. In this study, laboratory exposure experiments on juvenile sea cucumber (Apostichopus japonicus) were performed for seven antibiotics (sulfadiazine, sulfamethoxazole, trimethoprim, enrofloxacin, ofloxacin, clarithromycin, and azithromycin). Field sea cucumber and surrounding seawater samples were also analyzed. Results show that the sea cucumbers tend to accumulate high concentrations of the antibiotics with kinetic bioconcentration factors (BCFs) up to 1719.7 L•kg −1 for ofloxacin. The BCFs determined in the laboratory agree well with those estimated from the field measurements. Seven biotransformation products (BTPs) of the antibiotics were identified, four of which were not reported previously in aquatic organisms. The BTPs were mainly found in the digestive tract, indicating its high capacity in the biotransformation. A multicompartmental toxicokinetic model based on the principles of passive diffusion was developed, which can successfully predict time-course concentrations of the antibiotics in different compartments of the juvenile sea cucumbers. The findings may offer a scientific basis for assessing health risks and guiding healthy mariculture of sea cucumbers.

Tissue-Specific Accumulation, Biotransformation, and Physiologically Based Toxicokinetic Modeling of Benzotriazole Ultraviolet Stabilizers in Zebrafish (Danio rerio)

“…In the depuration phase, C UV-P,j decreased quickly in all of the tissues and dropped below LODs in the gills, intestines, livers, ovaries, and muscles between days 32 and 34. Previous studies also observed rapid uptake and depuration of chemicals with low log K OW (e.g., sulfonamides 68 ) in aquatic organisms, while those with high log K OW (e.g., dioxins 69 ) were the opposite.…”

Generic Solving of Physiologically-based Kinetic Models in Support of Next Generation Risk Assessment Due to Chemicals

“…Given parameter values in Table 4, we performed simulations over time for the six antibiotics and the four internal organs. As shown in Figure 6, we reproduced the same median curves as those of 46 in Figure S10 of their supplementary information.…”

“…Two case studies concern the species Gammarus fossarum exposed to cadmium (Cd). 27, 45 The third one concerns Apostichopus japonicus sea cucumber exposed to six different antibiotics; 46 the fourth one concerns species Danio rerio exposed to arsenic (As). 47 Gestin and colleagues 27,45 used several one-compartment PBK models compared with one four-compartment PBK model to gain knowledge on the accumulation and fate dynamic of Cd in and between gammarids' organs.…”

“…5). Based on the original paper, 46 biological parameter values were extracted to calculate the model's coefficients used for the simulations. All these parameters are provided in Table 4.…”

“…for uptake and elimination rates from or towards seawater, respectively; parameters k i,j represent from and back exchanges between compartments i and j, ∀i, j = 1,5. 46…”