There’s not a place on Earth free from plastic now. For 75 years, plastic has been a ubiquitous part of the human experience, and since day one, it has been shedding micro- and nanoplastic shards everywhere.

Researchers from Columbia University have now shown why the unique construction that makes plastic so useful also makes it break off into tiny fragments: the layered structure that makes semicrystalline plastic both strong and flexible.

When left alone in water, no sunlight, waves or agitation at all, the softer parts of semicrystalline plastics break down, leading to cracks that release stacks of nanoplastics into the environment.

The tougher, crystalline layers stay intact. The research found that only plastics with a structured, layered design create nanoplastics. These fragments were very different from smooth, lab-made plastic particles, which means they could behave differently in the environment or in living things. A gentle reminder of how much plastic is already found in our oceans, washing machines and water-based human bodies.

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