Study Offers Possible Mechanism for Microplastic-Linked Inflammation

The study found that as plastics wear down to microscopic sizes, their surface-to-volume ratio increases sharply. Wei Min, a chemist at Columbia University and one of the senior authors, said that when a credit card is fragmented into particles about 10 microns in diameter, its surface area increases more than 200-fold. That amplifies any chemical activity.

Min and colleagues examined polystyrene, polyethylene, polyvinyl chloride, polypropylene and polyethylene terephthalate. Plastic surfaces are hydrophobic and repel water, Min said, so water molecules cannot form the hydrogen bonds they maintain in liquid form. That changes molecular arrangements and, in turn, the local electrical environment and chemical reactivity.

The presumed chemical inertness of bulk plastics overlooks the toxicity of their fragmented microscale forms, according to the report. 'For microplastics, this is especially important because fragmentation creates enormous amounts of new surface area,' Min said.

Past research has shown that microplastics can cause inflammation, oxidative stress and decreased mitochondrial activity. The new study provides a possible mechanism, showing that plastic-water interfaces can perturb proteins, cell membranes and more.

How this might contribute to damage in living human tissues is still unclear, Min said. 'Ultimately, we hope to connect fundamental interfacial chemistry with quantitative measurements of biological effects, which would help us better understand potential health risks,' he added.