Scientists have discovered that microplastics, previously thought to be chemically stable, can react with water to become a significant biological hazard. This unexpected reactivity occurs under normal environmental conditions and could explain some of the cellular damage observed from microplastic exposure.
While larger plastic items are known for their chemical inertness, crucial for uses like food packaging, this new research from Columbia University and UC Berkeley reveals a different story for their microscopic counterparts. Microplastics, tiny fragments found everywhere on Earth, can have their surfaces activated by water, leading to the spontaneous formation of chemicals that can alter essential biological molecules.
The increased surface area of microplastics is key to this phenomenon. "As plastic fragments into smaller and smaller particles, its surface area increases enormously," explained Wei Min, a professor at Columbia University. "Then microplastics change the water that surrounds them, generating high-energy, reactive radicals that very likely contribute to biological damage."
Among the dangerous byproducts are reactive oxygen species, particularly hydroxyl radicals. These molecules are notorious for their ability to strip electrons from vital cellular components like proteins and fats, leading to structural damage and functional disruption. "These are textbook examples of the kinds of molecules that can damage animal and human tissue," stated Naixin Qian, a postdoctoral researcher involved in the study.
The body has natural defenses against such damage through antioxidants, but a high concentration of these reactive chemicals can overwhelm these systems, leading to oxidative stress and cell damage. Previous studies have linked microplastic exposure to oxidative stress, but the precise mechanisms were unclear until now.
The researchers are particularly concerned about microplastics' potential effects in the bloodstream, which is largely water. Experiments showed that when microplastics were exposed to mouse red blood cells, the cells deformed and ruptured, a process called hemolysis, with more reactive plastics causing greater damage. This challenges the long-held assumption that microplastics are chemically inert and points to a new, significant danger beyond the pollutants they might carry.
