Microplastics and per- and polyfluorinated alkyl substances (PFAS) are increasingly common in agricultural soils, and new research shows that their interaction could have significant implications for food safety. A study published in Eco-Environment & Health (DOI: 10.1016/j.eehl.2026.100216) found that different types of microplastics can either increase or decrease the uptake of PFAS by vegetables, depending on the polymer.
PFAS are persistent synthetic chemicals used in many industrial and consumer products due to their water- and oil-resistant properties. When they enter soil, they can be taken up by crops, creating a direct route of exposure for humans. Microplastics, defined as plastic particles smaller than 5 millimeters, are also widespread in farmland through sources like plastic mulching, wastewater irrigation, and sewage sludge. While previous studies have shown that microplastics can adsorb pollutants or alter soil processes, how different microplastic types affect PFAS uptake in edible vegetables was unclear.
Researchers from Nanjing University's State Key Laboratory of Water Pollution Control and Green Resource Recycling examined the effects of polyvinyl chloride (PVC), polylactic acid (PLA), and tire wear particles (TWP) on the uptake of 10 PFAS by pak choi (Brassica chinensis L.). They discovered that PVC significantly increased total PFAS accumulation in the plant's shoots by 1.31- to 1.70-fold across all tested doses, including at 0.01%, a level comparable to the upper range reported in farmland soils. This increase was not due to adsorption but to changes in plant physiology—PVC exposure upregulated aquaporin-related genes, including PIP1-1, TIP1-1, and TIP1-2 in shoots and NIP5-1 in roots, which enhanced water transport and likely facilitated PFAS movement into edible tissues.
In contrast, tire wear particles reduced PFAS accumulation in shoots by 37.4%–54.1%. TWP showed the strongest PFAS adsorption capacity, but it also suppressed plant growth and transpiration. At the highest dose, TWP reduced transpiration rate 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 opposing effects on toxicity, sorption, and aquaporin expression largely 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 the transfer of PFAS 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, and risk assessment 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 PFAS 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 research should test more crop species, realistic field conditions, and mixed plastic pollution scenarios to support stronger strategies for preventing PFAS and microplastics from entering the food chain.
