Microplastics and per- and polyfluoroalkyl substances (PFASs) are increasingly found together in agricultural soils, raising concerns about their combined impact on food safety. PFASs, known as 'forever chemicals' due to their persistence, are widely used in industrial and consumer products for their water- and oil-resistant properties. Once in soil, they can enter vegetables, creating a direct dietary exposure pathway. Microplastics (MPs), plastic particles smaller than 5 millimeters, are also prevalent in farmland through sources like plastic mulching, wastewater irrigation, and sewage sludge application. Previous studies have shown that MPs can adsorb pollutants or alter soil and plant processes, but the effect of different MP types on PFAS uptake by edible vegetables remained unclear.
Researchers from the State Key Laboratory of Water Pollution Control and Green Resource Recycling at Nanjing University addressed this gap in a study published in Eco-Environment & Health (DOI: 10.1016/j.eehl.2026.100216). The study investigated how polyvinyl chloride (PVC), polylactic acid (PLA), and tire wear particles (TWP) influence the uptake of 10 PFASs by pak choi (Brassica chinensis L.).
The findings revealed 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 reported in farmland soils. The researchers linked this increase not to stronger adsorption, but to plant physiological regulation. PVC exposure upregulated aquaporin-related genes, including PIP1-1, TIP1-1, and TIP1-2 in shoots and 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%, partly because it showed the strongest PFAS adsorption capacity and partly because it suppressed plant growth and transpiration. At the highest dose, TWP reduced transpiration rate to 73% of the control and triggered oxidative stress, as indicated by changes in malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD). PLA inhibited growth and metabolism, but its opposing effects on toxicity, sorption, and aquaporin expression largely offset each other, leaving PFAS uptake mostly unchanged.
The authors emphasized that microplastic pollution cannot be treated as a single, uniform risk. PVC may increase the transfer of PFASs into edible vegetables by altering plant water-transport pathways, while TWP may reduce PFAS uptake but introduce a separate ecological concern by damaging plant growth. The key message is that the material identity of microplastics matters. Risk assessment should move beyond total microplastic abundance and consider polymer type, particle behavior, plant response, and co-existing contaminants when evaluating agricultural soil safety.
The study has important implications for food safety, soil management, and emerging 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 findings also suggest that biodegradable plastics such as 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 stronger strategies for preventing PFASs and MPs from entering the food chain.
