Microscopic fragments of plastic have spread to virtually every corner of the planet, found in ecosystems everywhere. While scientists long believed that plastic debris remained chemically inert, researchers at Columbia University and UC Berkeley have discovered that water can make the surfaces of microplastics chemically active and transform them into a potential biological hazard.
Findings Published in Nature
According to findings published in Nature, this chemical activity can trigger the spontaneous creation of reactive agents capable of altering critical molecules required by living organisms. This phenomenon occurs under normal environmental conditions without needing sunlight or other external agents that typically cause plastic degradation. The greater available surface area of tiny fragments compared to larger objects drives these reactions.
Insights From Columbia University
Wei Min, a professor of chemistry and biomedical engineering at Columbia University, explained that as plastic breaks down into smaller particles, its surface area increases enormously. Wei Min noted that microplastics then alter the surrounding water, generating high-energy reactive radicals that likely contribute to the biological damage observed in animals and potentially humans following exposure.
Hydroxyl Radicals and Cellular Damage
Among these potentially dangerous chemical products known as reactive oxygen species, hydroxyl radicals stand out. They can snatch electrons from the fats and proteins comprising cell membranes, thereby disrupting their structure and function. Naixin Qian, a postdoctoral researcher in Min's lab who helped lead the research, added that these represent textbook examples of molecules capable of damaging animal and human tissue.
Antioxidants and Oxidative Stress
Human bodies maintain defenses against such damage through antioxidant molecules designed to neutralize reactive chemicals. However, when reactive compounds significantly outnumber antioxidants, this defense line becomes overwhelmed. This can develop into oxidative stress leading to cell damage, a response previously associated with microplastic exposure even though the underlying mechanisms were not fully understood.
Impact on Red Blood Cells
Researchers examined red blood cells extracted from mice by exposing them to various types of microplastics. The cells deformed and ruptured in a process known as hemolysis, and the effects proved greater with plastics that showed higher water reactivity, indicating that this chemical activity caused the cellular damage.
Challenging Longstanding Assumptions
Research into microplastics has historically focused on chemicals leaching from the particles or their physical effects, often treating the plastic itself as inert. These new findings challenge the core assumption that microscopic breakdown pieces behave just like larger plastic objects.
