Do polyethylene terephthalate microparticles (PET-µPs) affect the oxidative status of the clam Ruditapes philippinarum?

Polyethylene terephthalate (PET) is the most favorable polymer used as packaging material (e.g., drinking water bottle). PET items continue to be marketed for four decades but their uncorrect disposal represents an underestimated environmental problem. Moreover, in the environment PET can be degraded by diverse environmental factors, resulting in the formation of PET microplastics (PET-µPs). Microplastics, plastic particles < 5 mm, represent a major concern in the marine ecosystems because they are the predominant form of plastic debris and are small enough to be ingested by and potentially threathen marine organisms. Several monitoring studies have demonstrated the presence of PET-µPs in marine sediments and their ingestion in diverse marine species worldwide. However, there is a dearth of information on PET-µPs potential ecotoxicity. This study aimed at exploring the ingestion and potential effects on oxidative status (i.e., pro-oxidant production, modulation of antioxidant enzyme activity and oxidative damage) caused by a 7-days exposure to two concentrations (0.125 and 12.5 µg/mL) of PET-µPs in the clam Ruditapes philippinarum. Although PET-µPs were efficiently ingested and egested by clams, null or negligible effects on oxidative status were found, suggesting a low risk towards our model species, at least at the tested concentrations and for short-term exposure periods.