Pure, old water could be responsible for producing plastics that are harmful to humans, according to a new study that portends significant consequences for human health.
The study, published on October 14 (2026) in the scientific journal Naturediscovered chemical reactions between water and six types of fossil fuel-based plastics, generating particles that damaged red blood cells and proteins in laboratory tests.
As plastic in the body breaks down into smaller and smaller pieces — called microplastics and nanoplastics — the potential danger increases, said Dr. Min Wei, lead author of the study and professor of chemistry and biomedical engineering at Columbia University.
“Whether this phenomenon is responsible for 5% or 90% of the health effects that we see, I cannot answer,” he said in an interview.
“But I would be surprised if that doesn’t play a role.”
The interactions between water and plastic could help explain why other studies have shown that microplastics trigger inflammation, which contributes to various diseases that together account for more than half of all deaths worldwide.
At the moment, it is impossible to prevent these reactions within the body.
Human blood is about 50% water and cells are up to 80% water, Professor Min noted.
“This challenges the prevailing theory that plastic is inert (meaning it does not cause chemical or biological reactions),” said Dr. Sherri “Sam” Mason, who studies plastic pollution in freshwater.
“I think this highlights the need for a truly biodegradable plastic, rather than what industry is increasingly putting on the market,” said the chemist at Gannon University in Erie, Pennsylvania, US, who was not involved in the new study.
Scientists are also discovering microplastics in almost every part of the human body, for example the brain, heart, ovaries and testicles.
The fragments, most of them invisible, circulate in the blood and pass from mother to child through the placenta and breast milk.
Emerging research suggests that ingesting and inhaling microplastics — almost all of which are made from climate-changing fossil fuels — contributes to, or outright triggers, heart disease, dementia, Parkinson’s disease, fertility disorders and premature birth, among other health problems.
Professor Min and 11 colleagues, including researchers from the University of California, Berkeley and Rutgers University, both in the United States, found that water molecules behave differently when they come into contact with microplastics.
Water essentially acts as a catalyst that spontaneously creates particles called hydroxyl radicals, unstable molecules linked to aging and disease.
Two common types of plastic – polyethylene and polypropylene, widely used to make food containers, packaging, milk jugs and bottle caps – produced the most hydroxyl radicals detected by the researchers.
These results suggest that some plastics could be reformulated or phased out of consumer products, Professor Min said.
“Our bodies have natural defense mechanisms,” said Dr. Phoebe Stapleton, study co-author and Rutgers professor of pharmacology and toxicology.
“But depending on what other exposures we’ve had, our genetics and our lifestyle choices, all of these elements (hydroxyl radicals) could build up to a point where we can’t handle them anymore.”
More than eight billion tons of plastic already pollute the Earth.
Manufacturers, including the world’s largest oil companies, plan to triple production by 2060.
Craig Davis, senior director of plastics chemistry at the American Chemistry Council, the industry’s leading trade group, said in an email that the study “offers a new look at microplastics outside the body.”
But he said: “This does not establish whether the observed effects occur within the body’s complex biological systems or at actual levels of human exposure to microplastics.
“Additionally, the limited information on the particles tested in the version provided also makes the results difficult to fully evaluate.
“These gaps are important before drawing conclusions about human health. »
Professor Min acknowledged the study’s limitations.
Still, he said, the findings should help guide future research.
He noted that a group of Chinese researchers found that mixing plastic waste in hot water caused similar chemical changes that broke down polymers into the building blocks of new plastics, raising the possibility of a less toxic and more effective way to keep plastic waste out of the environment. – By Michael Hawthorne/Chicago Tribune/Tribune News Service
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