Determining the accumulation potential of nanoplastics in crops: An investigation of ¹⁴C-labelled polystyrene nanoplastic into radishes

The capacity of crops to accumulate nanoplastics has remained relatively unexplored largely due to analytical constraints. To address this challenge, the present study employed a radiolabelling approach to demonstrate, for the first time, that polystyrene nanoplastics (¹⁴C-PS NPs) accumulate and move into the edible tissues of radishes (Raphanus sativus). Radishes were exposed hydroponically for five days, with only their non-fleshy roots in contact with the ¹⁴C-PS NPs, while accumulation in the fleshy (edible) roots and shoots was subsequently measured. The radish roots retained nearly 5 % of the ¹⁴C-PS NPs from the exposure, either through accumulation or surface adsorption on the non-fleshy root system. The presence of ¹⁴C-PS NPs in the fleshy root and shoots supports the notion that PS NPs can cross the Casparian strip, facilitating uptake and accumulation into the internal plant tissues. The distribution of associated ¹⁴C-PS NPs followed the trend of non-fleshy root > fleshy root > shoots, decreasing further from the site of exposure. Notably, ∼25 % of the accumulated ¹⁴C-PS NPs were detected in the edible fleshy root, and approximately 10 % in the shoots. These results highlight a potential pathway for human exposure to nanoplastics through the ingestion of edible plant parts, which requires further exploration, underscoring the need for further research into this emerging food safety issue.