Microplastics generate reactive molecules where they meet water
Six common plastics generated reactive molecules on contact with water in a peer-reviewed laboratory study. Experiments linked these reactions to protein aggregation and damage to mouse red blood cells. The findings identify a possible chemical mechanism of injury, while leaving its contribution to disease in people unresolved.
Science··Night
Reactions begin at the water boundary
Six widely used plastics generated hydroxyl radicals, highly reactive molecules, where their surfaces met water. The peer-reviewed laboratory study examined polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyethylene terephthalate and poly(methyl methacrylate). Electron spin resonance and fluorescence imaging detected the reactions. More water-repelling surfaces generally showed greater chemical activity, connecting the effect to properties of the boundary between water and plastic.[1], [2]
A dye breaks down in water
Methyl orange, a dye used in the experiments, gradually degraded in water containing polystyrene. The same effect did not appear with the other solvents tested. Molecular simulations and quantum calculations explored how the arrangement of water molecules and the electrical environment at the surface could facilitate radical formation. These calculations supplied a proposed explanation alongside the laboratory measurements.[1]
Protein and mouse-cell experiments follow
In further experiments, the protein lysozyme formed aggregates. Caffeine, which neutralizes radicals, and a surface coating reduced aggregation. Red blood cells taken from mice also fragmented after contact with plastic particles. These experiments concern proteins and cells outside the human body. They do not establish how much the mechanism contributes to human disease, or whether every plastic product behaves the same way.[1]
