Effects of chronic exposure to microplastics and microplastics associated with polychlorinated biphenyl 153 on Daphnia magna

The present study investigates the potential effects and risks of polyethylene microbeads (PEMBs) and PEMBs associated with PCB-153 (PEMB-PCB) on Daphnia magna using a chronic exposure study approach. Daphnia magna were exposed to PEMBs, PCB-153, and PEMB-PCB for 21 days. Accumulation of PEMBs and PCB-153 in D. magna and effects on survival and reproduction of the organisms were measured. Overall, D. magna ingested and accumulated PEMBs and PCB-153. The accumulation of PEMBs increased with exposure time and was higher for PEMB exposure than for PEMB-PCB exposure. However, PCB-153 accumulation did not appear to increase over time. Exposure to PCB-153 in water resulted in higher PCB-153 accumulation than did PEMB-PCB exposure. Polyethylene microbeads and PCB-153 appeared to interact, resulting in a lower accumulation of PEMBs and PCB-153 and causing less effect on reproduction of D. magna. Survival of D. magna was affected by PEMBs, PCB-153, and PEMB-PCB. Results of the present study reveal potential risks of MPs to living organisms and ecosystems, especially when considering long-term exposure, which is relevant for microplastic pollution because of the persistence and continuous increase in MP abundance in the environment. More research should be conducted to understand the interactive effect mechanisms of MP and pollutant mixture exposure on organisms that would help explain the decreased accumulation of pollutants in organisms when MPs are present.