Bioaccumulation, Metabolism, and Biomarker Responses in Hyriopsis cumingii Exposed to 4-Mono-Chlorinated Dibenzothiophene

Polychlorinated dibenzothiophenes (PCDTs) are sulfur analogues of polychlorinated dibenzofurans with prevalent occurrence in aquatic environments and potential ecological risks. However, data on the behavior and toxicity of PCDTs in aquatic organisms remain scarce. In the present study, the bioaccumulation, metabolism, and oxidative damage of 4-mono-chlorinated dibenzothiophene (4-mono-CDT) in freshwater mussel (Hyriopsis cumingii) were investigated after exposure to 4-mono-CDT in semistatic water. The uptake rates, depuration rates, half-lives, and bioconcentration factors of 4-mono-CDT in hepatopancreas, gill, and muscle tissues ranged from 0.492 to 1.652 L d(-1) g(-1) dry weight, from 0.117 to 0.308 d(-1), from 2.250 to 5.924 d, and from 2.903 to 8.045 x 10(3) L kg(-1) dry weight, respectively. A dechlorinated metabolite (dibenzothiophene) was detected in hepatopancreas tissue, indicating that dechlorination was the main metabolic pathway of 4-mono-CDT. As the exposure time increased, the activities of superoxide dismutase, catalase, and glutathione peroxidase were induced or inhibited in the different experimental groups. The malondialdehyde content increased with increasing 4-mono-CDT dose and exposure time. A higher concentration of 4-mono-CDT corresponded to a greater integrated biomarker response in each tissue and greater oxidative damage. The antioxidant enzymes in hepatopancreas were more sensitive to 4-mono-CDT than those in gill. The results provide useful information on the behavior and ecotoxicity of PCDTs in freshwater mussels. Environ Toxicol Chem 2021;00:1-10. (c) 2021 SETAC

Automated summary

The research findings suggest that the behavior and ecotoxicity of PCDTs in freshwater mussels were studied by investigating the bioaccumulation, metabolism, and oxidative damage of 4-mono-chlorinated dibenzothiophene (4-mono-CDT) in freshwater mussels after exposure to it. The results show that dechlorination was the main metabolic pathway, and higher concentrations of 4-mono-CDT led to greater oxidative damage in the mussels.