Microplastics Chemically React With Water, Potentially Generating Harmful Radicals
Scientists at Columbia University and UC Berkeley have discovered that water activates the surfaces of microplastics, generating reactive oxygen species that can damage cells.
What happened
Researchers published findings in Nature demonstrating that microplastics undergo chemical reactions when exposed to water, even under normal environmental conditions without sunlight or degradation agents. The reactions generate reactive oxygen species, particularly hydroxyl radicals, which can strip electrons from proteins and fats in cell membranes and disrupt their structure. The phenomenon occurs because microplastics have vastly greater surface area than larger plastic pieces, enabling these reactions. When researchers exposed mouse red blood cells to different microplastics, the cells deformed and ruptured; the damage was greater with plastics that reacted more intensely with water, confirming the reaction mechanism was responsible.
Context
This finding challenges the longstanding assumption that microplastics, like bulk plastic, are chemically inert. The human body has antioxidant defenses against reactive oxygen species, but if microplastics generate these compounds in sufficient quantities, they can overwhelm this defense system and trigger oxidative stress, leading to cellular damage. Blood, which is largely water, presents particular concern as a site where microplastic reactions could occur if the particles are present in the body. Prior research had associated oxidative stress with microplastic exposure but had not identified the mechanism; this work suggests the microplastics themselves, not just contaminants they carry, may be a source of biological harm. The extent of microplastic accumulation in human tissues remains debated, but even small amounts could pose a hazard if they are chemically reactive in the aqueous environment of the body.
What's disputed
The extent to which microplastics have pervaded human bodies remains an open debate, with some sensational findings having been called into question. The full range of biological mechanisms responsible for microplastic-related damage is not yet fully understood.