Microplastics and per- and polyfluoroalkyl substances (PFAS) are two of the most persistent environmental contaminants, and they often co-occur in agricultural soils. A new study published in Eco-Environment & Health (DOI: 10.1016/j.eehl.2026.100216) reveals that the type of microplastic present can significantly alter how plants absorb these 'forever chemicals,' with some plastics increasing uptake and others decreasing it.
Researchers from Nanjing University examined the effects of three common microplastic types—polyvinyl chloride (PVC), polylactic acid (PLA), and tire wear particles (TWP)—on the uptake of 10 PFAS compounds by pak choi (Brassica chinensis L.). The study found 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 environmentally relevant levels of 0.01%.
The mechanism behind this increase was not stronger adsorption of PFAS by the plastic, but rather changes in the plant's physiology. PVC exposure upregulated aquaporin-related genes, including PIP1-1, TIP1-1, and TIP1-2 in shoots and NIP5-1 in roots, which enhance water transport and may facilitate the movement of PFAS from soil into edible tissues.
In contrast, tire wear particles reduced PFAS accumulation in shoots by 37.4%–54.1%. TWP showed the strongest adsorption capacity for PFAS among the tested plastics, 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, as indicated by changes in malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD).
Polylactic acid, a biodegradable plastic, 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 stress that microplastic pollution cannot be treated as a single, uniform risk. The material identity of microplastics matters, and risk assessments should move beyond total microplastic abundance and consider polymer type, particle behavior, plant response, and co-existing contaminants when evaluating agricultural soil safety.
These findings have important implications for food safety and soil management. Because PVC increased PFAS accumulation even at levels comparable to those found in real farmland soils, areas contaminated with 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 could harm crop performance. The study also cautions 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 develop stronger strategies for preventing PFAS and microplastics from entering the food chain.
