Toxic effects of fluoxetine-loaded onto virgin or aged polypropylene, polyamide and polyvinyl chloride microparticles on Daphnia magna

There is an increasing recognition that microplastics can act as a vector for micropollutants when co-occurring in the environment and that pollutant-loaded microplastics can become integral to food-webs. To evaluate whether fluoxetine-loaded microplastics can act as a vector for fluoxetine to enter the food chain, a toxicity assay with Daphnia magna neonates was performed. This study evaluated the fluoxetine availability when adsorbed onto virgin or aged polypropylene, polyamide, and polyvinyl chloride (PVC). Results demonstrated that fluoxetine-loaded microplastics displayed toxic effects for all microplastic types, with varying toxicity depending on plastic type and weathering. D. magna ingested microplastics in all experiments that microplastics were present, but survival rates were not significantly affected by microplastics alone. Neonate mortality did not correlate with the adsorption/desorption capacity of the microplastics. Fluoxetine showed the highest adsorption on virgin and aged polypropylene (83-98 %), followed by aged polyamide (25-68 %) and PVC (38-90 %). While negligible desorption occurred with polypropylene, polyamide and PVC exhibited up to 20 % desorption. However, higher mortality was observed with fluoxetine-loaded virgin polypropylene (30 %), polyamide (40 %), and PVC (35 %) compared to aged particles (0-10 %). The results indicate that microplastic can enter the food-chain and act as a vector for pollutants, exhibiting hazardous effects to wildlife.