Influence of polystyrene nanoplastics on the uptake and distribution of potentially toxic elements in tomato plants investigated using isotopic tracers.

This study evaluated the impact of 200 nm polystyrene (PS) nanoplastics (NPs) on the uptake and distribution of potentially toxic elements (PTEs), including chromium (Cr), cadmium (Cd), lead (Pb), and zinc (Zn), in hydroponically grown tomato plants. To distinguish naturally occurring PTEs from those taken up by the plants from nutrient solutions, enriched isotopic tracers were used, while europium (Eu)-labelled PS NPs enabled following the presence of NPs in plant tissues via ICP-MS analysis. After accounting for Eu leaching, intact PS-Eu NP concentrations were highest in roots and decreased by approximately three-orders-of-magnitude in shoots. Scanning electron microscopy revealed the presence of internalized particles with size and morphology similar to PS-Eu NPs in roots; however, significant Eu leaching under acidic biological conditions during long-term exposure limited verification of NP translocation to shoots, particularly fruits. PS-Eu NPs did not significantly affect Cd and Zn uptake, but reduced Cr and Pb uptake and translocation in tomato, most likely due to their increased association with NPs, resulting in their reduced bioavailability due to NPs agglomeration and sedimentation. The influence of NPs on other macro- and naturally occurring trace elements was element-specific, indicating broader effects on plant nutritional composition and fruit safety. We showed that elevated Cd accumulation in tomato fruits, irrespective of NP presence, poses health risks under chronic consumption, especially for children. These findings highlight the importance of regulating NP and PTE concentrations in water used for plant irrigation and monitoring their accumulation in edible plant tissues to ensure food safety.