Comparative uptake and translocation of polyvinyl chloride (PVC) and polypropylene (PP) nanoplastics in carrot, lettuce, and wheat

Abstract

Plastic particles smaller than one micrometer, termed nanoplastics (NPs), are pervasive in agricultural systems. Uptake of these particles in plants has been demonstrated, yet cross-species comparisons remain scarce, with most work to date focusing on polystyrene particles. Here, we investigated how gadolinium-labelled polyvinyl chloride (PVC; ∼257 nm) and polypropylene (PP; ∼352 nm) NPs are taken up and redistributed in three representative crops, carrot (Daucus carota), lettuce (Lactuca sativa), and wheat (Triticum aestivum). Using inductively coupled plasma–mass spectrometry, we quantified the Gd label to calculate the NP accumulation in roots and shoots. All species absorbed both types of NPs, with roots consistently serving as the dominant reservoir and root concentrations exceeding shoot concentrations by one or two orders of magnitude. Root-to-shoot translocation was generally limited, with translocation factors typically below 5%, but varied strongly among species, ranging from <1% in wheat to approximately 4% in carrot, with lettuce showing intermediate values. Differences between PVC and PP were also observed, with PVC showing higher uptake and translocation compared to PP. We also observed species-dependent growth responses, with lettuce exhibiting a reallocation of biomass from roots to shoots, whereas carrot and wheat were largely unaffected. These results highlight the need to consider both crop-specific traits and polymer type when assessing NP uptake and redistribution in plants, while the potential implications for food safety and health risks in agroecosystems should be evaluated further under soil-based and environmentally realistic exposure conditions.