Microplastics May Become Chemically Active in Water, Scientists Find

One of the reasons plastics have become so ubiquitous is their chemical stability. They generally do not react easily with the materials around them, which is why they are widely used in food packaging and water bottles.

Scientists once thought the same stability applied to microplastics. These tiny particles break off from larger plastic objects and, according to numerous studies, have spread to nearly every ecosystem on Earth. However, researchers at Columbia University and the University of California, Berkeley, have discovered that water can chemically activate the surface of microplastics, potentially turning them into hazards.

Water Can Activate the Surface of Microplastics

According to findings published in Nature, this activity can lead to the spontaneous formation of chemicals capable of changing other molecules, including molecules essential to living organisms. The authors note that the phenomenon occurs under normal environmental conditions, without sunlight or other factors typically associated with plastic degradation.

Why Smaller Plastic Particles May Be More Reactive

Scientists suggest that microplastics may be more reactive than larger pieces of plastic because they have a much greater surface area available for chemical reactions.

“As the plastic breaks down into smaller and smaller particles, its surface area increases significantly,” said Wei Ming, a professor of chemical and biomedical engineering at Columbia University, in a press release. “The microplastics then alter the surrounding water, producing high-energy reactive radicals. This is very likely to contribute to the biological damage seen in animals and potentially humans as a result of exposure to microplastics.”

Reactive Oxygen Species Could Damage Cells

Among the potentially dangerous chemicals produced through this process are reactive oxygen species. A class known as hydroxyl radicals is particularly concerning because these molecules can take electrons from the proteins and fats that make up cell membranes, damaging their structure and function.

“These are textbook examples of molecules that can cause damage to tissue in animals and humans,” added Naixin Qian, a postdoctoral researcher in Ming’s lab and the study leader.

Microplastics and Oxidative Stress

The human body has built-in defenses against this type of damage. Antioxidants neutralize reactive chemicals, but these defenses can become overwhelmed when reactive compounds greatly outnumber antioxidants.

This imbalance can lead to oxidative stress, a condition associated with cell damage. Previous studies have identified oxidative stress among the cellular responses linked to microplastic exposure, but the mechanisms responsible for this damage are still not fully understood.