Ecotoxicity of Plastic Nanoparticles in Quagga Mussels Dreissena bugensis

Small plastics polymers have the potential to bioaccumulate in tissues and initiate toxicity, raising concerns about the long-term impacts towards 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 Dreissena bugensis. Mussels were exposed to 5, 50 and 100 µg/L of the above compounds for 96h at 15oC. They were then analyzed for total plastic accumulation, esterase, peroxidase, lipids and protein aggregation in the soft tissues. The data revealed that DBP reduced survival at concentrations > 5 µg/L and all died at 100 µg/L. An estimated bioavailability factor of 90, 40 and 1580 for PVC, PET and DBP was 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.