Microplastics and per- and polyfluorinated alkyl substances (PFASs) are increasingly found together in agricultural soils, raising concerns about their combined impact on food safety. A new study from Nanjing University reveals that the type of microplastic present can significantly alter how vegetables absorb these 'forever chemicals,' with some plastics enhancing uptake and others reducing it.
PFASs are persistent synthetic chemicals used in industrial and consumer products for their water- and oil-resistant properties. Once in soil, they can enter crops, creating a direct dietary exposure pathway. Microplastics (MPs), particles smaller than 5 millimeters, are also widespread in farmland through plastic mulching, wastewater irrigation, sewage sludge, atmospheric deposition, and tire wear. Previous research has shown MPs can adsorb pollutants or affect plant processes, but how different MP types influence PFAS uptake by edible vegetables was unclear.
Researchers from the State Key Laboratory of Water Pollution Control and Green Resource Recycling at Nanjing University investigated how polyvinyl chloride (PVC), polylactic acid (PLA), and tire wear particles (TWP) affect the uptake of 10 PFASs by pak choi (Brassica chinensis L.). Their findings were published in Eco-Environment & Health (DOI: 10.1016/j.eehl.2026.100216) on January 19, 2026.
The study found sharply different effects among the three MP types. PVC significantly increased total PFAS accumulation in pak choi shoots by 1.31- to 1.70-fold across all doses, including at 0.01%, a level comparable to the upper range in farmland soils. The increase was linked not to stronger adsorption but to plant physiological changes. PVC exposure upregulated aquaporin-related genes (PIP1-1, TIP1-1, TIP1-2 in shoots, NIP5-1 in roots), suggesting enhanced water transport that may facilitate PFAS movement from soil into edible tissues.
In contrast, TWP reduced PFAS accumulation in shoots by 37.4%–54.1%. This reduction was partly due to TWP's strong PFAS adsorption capacity and partly because it suppressed plant growth and transpiration. At the highest dose, TWP reduced transpiration to 73% of the control and triggered oxidative stress, indicated by changes in malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD). PLA inhibited growth and metabolism, but its effects on toxicity, sorption, and aquaporin expression offset each other, leaving PFAS uptake mostly unchanged.
The authors emphasize that microplastic pollution cannot be treated as a single, uniform risk. PVC may increase PFAS transfer into vegetables by altering plant water-transport pathways, while TWP may reduce PFAS uptake but introduce separate ecological concerns by damaging plant growth. The material identity of microplastics matters, and risk assessments should consider polymer type, particle behavior, plant response, and co-existing contaminants when evaluating agricultural soil safety.
These findings have important implications for food safety, soil management, and contaminant regulation. Because PVC increased PFAS accumulation even at environmentally relevant levels, farmland contaminated by both plastic residues and PFASs may require closer monitoring. TWP deserves attention in roadside and industrial soils, where tire-derived particles may be abundant and phytotoxicity could affect crop performance. The study also suggests that biodegradable plastics like PLA should not be assumed risk-free without evaluating their ecological effects. Future work should test more crop species, realistic field conditions, and mixed plastic pollution scenarios to support strategies for preventing PFASs and MPs from entering the food chain.
