Quantifying the trophic transfer of sub-micron plastics in an assembled food chain

Sub-micron plastics (SMPs, size < 1 µm) are potentially taken up by plants. Serious concerns arise that how
far SMPs can transfer from plants into food webs. Here, we show that lettuce takes up 250 nm gadolinium
labelled polystyrene (PS) and polyvinyl chloride (PVC) SMPs from the soil. The polymer type influences the
biodistribution of the particles in lettuce (roots and leaves) and the number of particles transferred from the
plants to insects feeding on the treated lettuce. The SMPs were further transferred from insects to insect-
feeding fish to accumulate mostly in the fish liver. No Gd was released from the particles upon bio-
transformation (formation of protein corona on the particles) in the plants or insects. However, Gd ion was
detected in fish fed with PS-SMP treated insects, indicating the possible degradation of the particles. No
biomagnification in fish was detected for either type of SMPs. We conclude that plastic particles can po-
tentially transfer from soil into food webs and the chemical composition of plastics influences their bio-
distribution and trophic transfer in organisms.