Lifecycle Implications of Poly(vinyl chloride) (PVC) Micro(nano)plastics (MNPs): Interactions with Coexposed Environmental Pollutants (EPs) and Impact on Their Toxicity and Bioavailability

Sorption of environmental pollutants (EPs) on micro(nano)plastics (MNPs) across their lifecycle raises significant concerns regarding potential toxicological effects, but remains understudied. To address these knowledge gaps, we assessed the sorption of EPs, including toxic elements (arsenic (As), chromium (Cr), and lead(Pb)), and organic pollutants (boscalid and PFOS) on poly(vinyl chloride) (PVC) MNPs generated across their lifecycle by mechanical fragmentation/cryomilling, photo-oxidation, and incineration. The toxicological effects of EP-MNP coexposure were assessed using a small intestinal epithelium (SIE) model, coupled with a three-phase simulated GI digestion. Sorption of most EPs was MNP lifecycle-stage- and EP-specific, with aged-MNPs (cryomilled and UV photo-oxidized) having a higher EP affinity than unaged MNPs (cryomilled) and incinerated MNPs. While MNPs and EPs alone or combined did not produce cytotoxicity in the SIE, aged-MNPs and incinerated MNPs in the presence of EPs triggered oxidative stress, suggesting MNP lifecycle-stage and EP dependency. Importantly, MNP- and EP translocation across SIE were MNP concentration, MNP lifecycle-stage, and EP-dependent. Aged PVC (at 50 μg/mL) enhanced the translocation of Cr (78.8%), Pb (54.2%), boscalid (23.4%), and PFOS (56.9%), while incinerated PVC increased translocation of only boscalid (23.4%) and PFOS (56.9%) significantly when compared to EPs alone. EPs enhanced the translocation of aged PVC and incinerated PVC at 50 μg/mL by 102.2% and 54.0%, respectively, when compared to MNPs alone. Such reciprocal enhancement of the translocation of EPs and aged-MNPs, and of incinerated MNPs, correlated with the downregulation of cell junction genes, suggesting compromised cell junction integrity. Collectively, our findings offer significant toxicological insights into the lifecycle of ecologically relevant PVC MNPs, their interactions with EPs, and the consequent implications for the integrity of human intestinal epithelial structures.