Dynamic release of phthalate esters from pristine and aged microplastics in indoor environments and their potential...

Microplastics (MPs) in indoor environments are a significant source of phthalate ester (PAEs) release, posing potential health risks. This study investigated PAEs release kinetics from polyethylene (PE) and polylactic acid (PLA) in indoor air, and from four common MPs (polyamide, polycarbonate, polyethylene, and polylactic acid) at multiple aging stages (0, 7, 14, 21, and 28 days) in simulated lung fluids (ALF and GS) through simulation experiments. Results demonstrated that light, temperature, and aging degree significantly influence PAEs release. Aging altered surface properties (increased specific surface area and hydrophilicity), causing non-monotonic release trends of PAEs. Both light exposure and elevated temperature significantly promoted PAEs release (p < 0.05), with kinetics following a pseudo-second-order model, governed by surface desorption and intraparticle diffusion. PAEs release was significantly higher in ALF than in GS (p < 0.05). Aged MPs exhibited elevated relative concentrations of ·OH and ·O₂⁻ in lung fluids, indicating a potential oxidative burden. This study elucidates the dynamic release behavior of additives during aging of microplastics, and highlights the dynamic aging process of MPs as well as the potential health impacts.