Polymer identity determines nanoplastic toxicity: A toxicokinetic-toxicodynamic analysis

Area of Science:

• Environmental Toxicology
• Aquatic Ecotoxicology
• Nanomaterial Science

Background:

• Nanoplastics (NPs) are pervasive environmental contaminants in aquatic systems.
• Current research predominantly focuses on polystyrene (PS) NPs, neglecting the toxicological impact of other prevalent polymers.

Purpose of the Study:

• To compare the toxicity of four common nanoplastic polymers: polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS), and polyvinyl chloride (PVC).
• To investigate the toxicokinetics and toxicodynamics of these NPs in the freshwater protozoan Tetrahymena thermophila.
• To establish a mechanism-based framework for assessing polymer-specific NP toxicity.

Main Methods:

• Utilized Tetrahymena thermophila as a model organism for aquatic NP toxicity assessment.
• Employed aggregation-induced emission (AIE) labeling for accurate quantification of intracellular NP burdens.
• Applied a toxicokinetic-toxicodynamic (TK-TD) framework with a damage assessment model (DAM) to link internal doses to Ca2+ dysregulation.

Main Results:

• PMMA and PS NPs showed high accumulation but moderate toxicity.
• PVC NPs exhibited the highest toxicodynamic damage accumulation rate, indicating polymer chemistry dictates toxicity.
• Polystyrene (PS), commonly used in research, was the least potent NP type tested.

Conclusions:

• Aquatic nanoplastic risk assessment must expand beyond polystyrene (PS)-centric models.
• Polymer type significantly influences nanoplastic toxicity, with PVC demonstrating higher potency than PS.
• A predictive, mechanism-based framework is crucial for evaluating polymer-specific nanoplastic ecotoxicity.