Ecotoxicity of plastic nanoparticles in quagga mussels, Dreissena bugensis

Small plastic polymers have the potential to bioaccumulate in tissues and initiate toxicity, raising concerns about the long-term impacts on filter feeders such as freshwater mussels. The purpose of this study was to examine the toxicity of two common plastic polymers (polyvinyl chloride—PVC; polyethylene terephthalate—PET) and the plasticizer dibutylphthalate (DBP) to quagga mussels, also called Dreissena bugensis. Mussels were exposed to 5, 50, and 100 µg/l of the above compounds for 96 h at 15 °C. They were then analyzed for total plastic accumulation, esterase, peroxidase, lipids, and protein aggregation in soft tissues. The data revealed that DBP reduced survival at concentrations > 5 µg/l and all died at 100 µg/l. Estimated bioavailability factors of 90, 40, and 1580 for PVC, PET, and DBP were determined. These differences could be explained by particle size and form for PVC (0.5 µm fiber) and PET (2 µm diameter). DBP tissue levels were also detected in mussels exposed to PVC and PET, suggesting its presence in plastics. Esterase activity was strongly increased in DBP (ester)-treated mussels and was slightly decreased in mussels exposed to ester-containing PET. The biomarker data also revealed an increase in lipids, peroxidase, and protein aggregation in a concentration-dependent manner. It is concluded that these compounds are bioavailable to mussels and the changes in esterase activity could be a factor leading to oxidative stress and protein aggregation in mussel tissues.