New research from Columbia University has revealed that microplastics can trigger the release of highly reactive chemicals that may harm human health. Published recently in the journal Nature, the study challenges previous assumptions that plastics are chemically inert and safe within the human body.

The researchers found that when water comes into contact with tiny microplastic particles, it releases reactive oxygen species (ROS)—unstable molecules known to damage biological materials including proteins, DNA, lipids, and RNA. These molecules are implicated in a range of diseases such as heart disease, cancer, and neurological disorders like Alzheimer’s.

“We found that these high-energy molecules can interact with key biological molecules and cause damage, including mutations in DNA,” said Wei Min, a chemistry professor at Columbia and an author of the study.

While earlier research had established correlations between microplastic exposure and various health issues, the precise mechanism causing such damage remained unclear. This new work proposes that microplastics induce oxidative stress, a process where free radicals overwhelm the body’s antioxidant defenses, potentially leading to inflammation and chronic disease.

In laboratory experiments, the team exposed small particles of polystyrene—commonly found in Styrofoam—to water containing methyl orange dye. Over a period of 10 days, the dye degraded significantly, indicating the presence of reactive oxygen species. Similar effects were observed using other plastics such as polyethylene, used in food containers, and PET, typical in water bottles.

Recognizing that the human body is largely composed of water, the scientists also tested microplastics in blood serum and cell cultures. These tests confirmed the generation of ROS in biological fluids, reinforcing concerns about their impact on human health.

Astrid Delorme, a lecturer at the University of Hawaii at Manoa who studies plastic degradation but was not involved in the study, noted the significance of these findings. She said that the research challenges the conventional view that only weathered plastics undergo chemical changes, highlighting that pristine plastics can be chemically active in aqueous environments.

The study emphasizes the role of microplastic size in this chemical reactivity. Smaller particles have a much larger surface area relative to their volume, which enhances their ability to catalyze the production of harmful molecules. Min explained that when larger plastic objects break down into microplastics, their surface area can increase by a factor of a thousand, thus facilitating these reactions.

While the body has mechanisms to neutralize reactive oxygen species, researchers express concern that accumulated microplastics might produce ROS quantities exceeding these defenses, potentially triggering chronic inflammation.

“Plastics persist in the environment and the body for long periods,” Min said. “This finding suggests a need for increased awareness regarding the potential health risks associated with microplastic exposure.”