Microplastics release DNA-damaging chemicals on contact with water, study finds

A recent study published in the journal Nature has found that microplastic particles release highly reactive chemicals, known as reactive oxygen species (ROS), when they come into contact with water. These chemicals have been linked to heart disease, cancer, and neurological disorders such as Alzheimer’s. The discovery challenges the longstanding belief that plastics are among the safest materials.

Researchers at Columbia University conducted the study and discovered that these chemicals are produced even when new, pure plastic is exposed to water—not just when old, weathered plastic breaks down from sun and wind, according to The Washington Post.

Previously, companies and scientists believed that the long chemical chains in plastics did not react with food, water, or the human body, but the new findings prove otherwise.

In recent years, several studies have linked exposure to microplastic particles with a variety of health problems. Higher concentrations of microplastics in a major human artery have been associated with heart disease, and experiments in mice have shown symptoms similar to Alzheimer’s and atherosclerosis. However, these studies had not identified a clear mechanism for the damage.

The new study suggests that the chemicals released by microplastics may cause oxidative stress—a condition where the body produces dangerous free radicals in amounts that overwhelm natural defenses, potentially leading to inflammation and other health issues.

These chemicals can react with nearby biological molecules such as proteins, DNA, fats, and RNA, causing damage. They may also collide with DNA due to their high energy, resulting in mutations, according to Wei Min, a chemistry professor at Columbia University and one of the study’s authors.

In one experiment, researchers mixed polystyrene microplastic particles—used in foam cups and takeaway food containers—with water and methyl orange dye, which breaks down when exposed to reactive oxygen species.

After ten days, the dye had decomposed and the water remained nearly clear, indicating the presence of high-energy chemicals. The scientists also tested other common plastics, including polyethylene (used in cups and food container linings) and PET (used in water bottles).

Since the human body is mostly water, the researchers also examined the effect of microplastic particles in blood serum and cell cultures, finding that reactive oxygen species remained present.

These results are significant because it was previously believed that only old, weathered plastic could cause chemical effects. The study shows that even pure plastic becomes chemically reactive in water, according to Astrid Delorme, a lecturer at the University of Hawaii at Manoa who specializes in plastic degradation and was not involved in the study.

The reason lies in particle size: large pieces of plastic are unlikely to react with water, but microplastic particles have a much greater surface area, increasing the chances of forming hazardous molecules. When a plastic credit card breaks down into microplastic particles, its surface area increases a thousandfold, allowing water to split into reactive chemicals.

The human body does have defenses to eliminate reactive oxygen species, but scientists warn that the accumulation of microplastics could generate more reactive chemicals than the immune system can handle. Because plastics persist for so long, there is growing concern that they could lead to chronic inflammation.