Microplastics can become chemically active when they break down in water, according to a study published in Nature. Researchers from Columbia University and the University of California, Berkeley found that as plastic fragments break down into micro- and nanoplastics, the increased surface area exposes the materials to water, triggering chemical reactions. “As plastic breaks down into increasingly smaller particles, the surface area increases enormously,” said Wei Min, a professor of chemistry and biomedical engineering at Columbia. “We then see the water in which those particles float change. High-energy, reactive radicals are formed that contribute to biological damage.”
The study challenges the long-held belief that microplastics are chemically inert, a perception that contributed to their widespread use in food packaging, toys, and other products. The research highlights that water acts as a catalyst, generating reactive oxygen species that could harm tissues in animals and humans. “When plastics break down into smaller particles, their increasing surface-to-volume ratio creates more of these chemically active regions,” Min added. The findings suggest microplastics may be active in the bloodstream, as blood is predominantly water.
Chemical Reactivity in Water
The study identified specific chemical reactions that occur when microplastics interact with water, including the formation of reactive oxygen species. These radicals, which are highly reactive, could potentially damage biological tissues. The research builds on earlier work by Min’s team, which found that a liter of bottled water contains an average of 240,000 detectable plastic particles, mostly nanoplastics. This discovery has raised concerns about microplastics’ presence in the food system and their health impacts.
Potential Health Risks and Research Implications
Previous studies have linked exposure to microplastics with conditions such as heart attacks, strokes, dementia, and brain tumors, though the mechanisms remained unclear. The new research provides an explanation, showing that water’s role in activating microplastics may underpin these health risks. “When microplastics come into contact with water – as is the case in bottled water or in our bloodstream – they generate so-called reactive oxygen species that can eventually damage tissue in animals and humans,” said co-author Naixin Qian. The study emphasizes the need to reevaluate the chemical properties of common plastics to mitigate toxic reactions.
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