Oligomer self assembly is a major source of nanoplastic release from household plastic cutting boards

<title>Abstract</title> Plastic cutting boards are ubiquitous, yet the scale and health significance of their nanoscale emissions remain poorly characterized. Here we report that seven new commercial cutting boards, after a 10-minute chopping session (600 knife strikes), released 2,750–7,242 microplastics (62–164 µm) and 2.33 × 10⁷–1.12 × 10⁸ nanoparticles (104–200 nm). One month of photoaging increased nanoparticle yield by up to 963% and produced particles smaller than 50 nm. Chemical analyses revealed that 38.2–55.0% of nanoparticles from new boards were oligomer-derived, increasing to 92.7% after aging. Molecular dynamics simulations further showed that polypropylene oligomers self-assemble into spherical aggregates, whereas polyethylene forms layered structures. In zebrafish, polypropylene oligomers induced pericardial edema, bradycardia, and developmental defects at concentrations as low as 0.01 µg mL⁻¹. We integrated these release data with regional cooking statistics across 144 regions (2019–2022), identifying a global exposure peak in 2021 (7.94 × 10⁷ MPs; 1.90 × 10¹¹ NPs) driven by pandemic-era home cooking. The Americas showed the highest exposures, and high-income countries ingested more microplastics than low-income ones. This study reveals that self-assembled oligomer nanoparticles represent a major, previously overlooked contributor to dietary plastic exposure.