Effects and mechanisms of microplastic types on plant uptake of per- and polyfluorinated alkyl substances

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFASs) frequently co-occur in agricultural soils. MP type-dependent interactions with soil and plants can modify PFASs environmental behavior, complicating assessments of PFAS-related ecological and human exposure risks. This study investigated the effects of three MPs, namely polyvinyl chloride (PVC), polylactic acid (PLA), and tire wear particles (TWP), on the uptake of 10 PFASs by pak choi (<i>Brassica chinensis</i> L). PVC at 0.01%, 0.05%, and 0.5% significantly (<i>p</i> < 0.05) increased PFASs accumulation in shoots by 1.31-1.70 fold. The upregulation of aquaporin-related genes in pak choi co-exposed to PVC and PFASs represents a potential mechanism for the enhanced uptake and translocation of PFASs. In contrast, PLA did not affect PFASs accumulation but inhibited plant growth by downregulating lipid and amino acid metabolism. TWP at 0.01%, 0.05%, and 0.5% significantly (<i>p</i> < 0.05) decreased PFASs uptake in shoots by 37.4%-54.1%, primarily through its inhibitory effects on plant growth (9.2%-16.3% decrease in biomass) and transpiration rate (reduced to 73% of the control). The phytotoxicity of TWP was confirmed by metabolomic profiling, which was associated with downregulation of key lipid, amino acid, and jasmonic acid-related metabolites. This work provides the first systematic comparison of the effects of PVC, PLA, and TWP on PFASs uptake in vegetables, integrating multi-omics analyses to uncover mechanisms and distinct MP type-dependent effects on PFASs bioaccumulation. These findings highlight complex interactions between MPs and PFASs in soil and underscore the need to assess co-contaminant risks by MP types.