Researchers discovered that common microplastics spontaneously generate DNA-damaging free radicals upon contact with water, challenging long-held assumptions that synthetic polymers are chemically inert. Published on October 14, 2026, in the journal Nature, the findings reveal how microscopic particles in drinking water and human blood can actively attack proteins and living cells.
For decades, commercial plastics have enjoyed a reputation for stability. From polypropylene food containers to polyethylene milk jugs and PVC piping, these fossil fuel-derived polymers were presumed to sit quietly inside the human body or natural ecosystems without triggering unwanted chemical interactions. A joint team of researchers from Columbia University, the University of California, Berkeley, and other institutions has dismantled that assumption.
Free Radicals Formed at the Plastic-Water Interface
When microscopic plastic fragments mingle with water, they do not remain passive bystanders. Instead, microplastics become chemically active, generating reactive oxygen species. These hydroxyl radicals rank among the most destructive, unstable molecules known in biological systems.
Contact between the water and plastic creates an environment that facilitates electron transfer and the formation of reactive radicals. When plastics fragment into smaller particles, their increasing surface-to-volume ratio creates more of these chemically active areas.
Teresa Head-Gordon, chemistry and bioengineering professor at UC Berkeley
In laboratory imaging experiments led by Columbia chemist Wei Min and postdoctoral researcher Naixin Qian, researchers tested six common commercial polymer powders, including polystyrene, polypropylene, and polyethylene. Water-repellent plastics demonstrated the highest reactivity, producing unstable molecules that clumped proteins and ruptured mouse red blood cells in controlled tests.
Microplastics in Human Blood Create Biological Stress
The discovery carries particular weight because human blood contains a great deal of water. With scientists having already detected microplastics in human blood vessels, brain tissue, testicles, the placenta, and arterial plaque, the presence of these particles creates an ongoing source of biological stress.
Dr. David Christiani, professor of medicine at Harvard Medical School and the Elkan Blout professor of environmental genetics at the Harvard T.H. Chan School of Public Health, noted that microplastics are ubiquitous in the environment and have been found in food, water, and air. While small studies associate microplastics in blood and neck artery plaque with heart attacks, strokes, and mortality, researchers emphasize that proving direct causation remains complex.
The new research suggests that microplastics that enter the bloodstream or cells could remain chemically active in this water-rich biological environment.
Wei Min, Columbia University chemist and study co-author, via Yahoo News
Rutgers University professor of pharmacology and toxicology Phoebe Stapleton, who co-authored the study, explained that human bodies deploy natural defense mechanisms against cellular stress. However, she cautioned that environmental toxin exposures, genetics, and personal lifestyle choices can cause these reactive molecules to accumulate until physiological systems reach a breaking point.
Natural Lipids May Envelop Inhaled Plastic Fragments
Scientists investigating the mechanism also identified a potential buffering effect. This finding mirrors biological realities inside the human respiratory tract, where natural fats and lipids coat inhaled particles immediately upon contact.
Matthew Campen, a researcher not involved with the study, observed that microplastics hit your lung, and they are surrounded by surfactants immediately, noting that lipids in biological systems will likely envelop these fragments in a similar manner over time.
- Swap single-use plastic water bottles and food containers for glass or stainless-steel alternatives.
- Transfer leftovers to glass or ceramic dishes rather than microwaving food inside plastic containers.
- Replace plastic kitchen items, such as cutting boards and utensils, with wooden or metal equivalents.
- Wash synthetic clothing less frequently on cooler temperatures and hang them to dry.
With global plastic production continuing to generate hundreds of millions of metric tons annually—and single-use items accounting for roughly 40 percent of that total—the newly uncovered physicochemical reactivity adds urgency to regulatory discussions and the search for biodegradable materials.