Microplastics' vector effect on Co-bioaccumulation of it and polychlorinated biphenyls in Crassostrea hongkongensis

Microplastics (MPs) and polychlorinated biphenyls (PCBs) are known with high persistence and toxicity, posing urgent threats to food safety and human health. However, little is known about the synergistic effect of MPs on PCBs bioaccumulation on Crassostrea hongkongensis. In the present study, diverse types of MPs were analyzed on sea water and C. hongkongensis sampled from three distinct estuary sites, and film-shaped MPs were discovered to be preferentially ingested by the oysters. Interestingly, the content of MPs and PCBs showed negative correlation (R² = 0.452, p< 0.001) in the oysters sampled from site 2. Upon MPs and PCBs co-treatment, the in vivo accumulation of PCBs in C. hongkongensis was inhibited by 25.90 % when compared to the group treated with PCBs solely. PCBs stresses significantly induced the expression of genes of CYP2C31, GST, SOD and HSP70 in C. hongkongensis, while, the elevated state was compromised when co-treated with PCBs. The present research alleviates concerns about the potential effects of MPs on promoting PCBs bioaccumulation and provide a better understanding of the combined impact of MPs and PCBs on C. hongkongensis.