Slashdot has reported:

A study published in Nature suggests microplastics can interact with water to generate highly reactive molecules, offering a possible explanation for inflammation and other biological effects. Microplastics have been linked to heart attacks, stroke, dementia and brain tumours, but what drives those associations remains unclear.

When water contacts a plastic particle, molecules near its surface can become chemically active and modify nearby substances, including biologically important molecules. The researchers examined several kinds of microplastics: polystyrene, polyethylene, polyvinyl chloride, polypropylene and polyethylene terephthalate.

As plastic breaks into microscopic fragments, its surface area grows sharply relative to its volume. Wei Min, a Columbia University chemist and one of the study’s senior authors, said fragmenting a credit card into particles about 10 microns across increases its surface area by more than 200 times. He said this amplifies any chemical activity.

Min said plastic surfaces repel water, preventing water molecules from forming the hydrogen bonds they maintain in liquid form. This changes molecular arrangements and, in turn, the local electrical environment and chemical reactivity. The assumption that bulk plastics are chemically inert does not account for the toxicity of their fragmented, microscopic forms.

“For microplastics, this is especially important because fragmentation creates enormous amounts of new surface area,” Min said. Earlier research has found that microplastics can cause inflammation, oxidative stress and decreased mitochondrial activity. The new study offers a possible mechanism, finding that interfaces between plastic and water can disturb proteins, cell membranes and other substances.

How those effects might contribute to damage in human tissues remains uncertain, 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.