Microplastics may make harmful molecules when they touch water, study finds
Tiny bits of plastic can make harmful molecules when they touch water, a new study in Nature found. New Scientist and Scientific American reported on the lab work, which was led in part by Wei Min of Columbia University. It may help explain why microplastics are tied to health problems.
Tiny pieces of plastic can produce harmful molecules called hydroxyl radicals when they come into contact with water, New Scientist and Scientific American reported. The lab study was published in the journal Nature.
Microplastics form when plastic breaks down. They have been linked to health problems such as heart disease and poor thinking, but it has not been clear why, both outlets reported.
Plastics are usually thought of as safe and unreactive. "From a pure chemistry point of view, this should be inert," said Wei Min, a chemist at Columbia University, New Scientist reported.
The team tested common plastics, including polystyrene, polyethylene and polypropylene, Scientific American reported. Using special microscopes and other tools, they found that hydroxyl radicals form on their own where plastic meets water, New Scientist reported. Electric charges at that surface seem to drive the effect.
In tests, the particles appeared to damage proteins and red blood cells, New Scientist reported. In blood serum the effect was weaker but "still detectable," Min said.
Size matters because small bits have far more surface. Breaking a credit card into particles about 10 microns wide raises its surface area more than 200-fold, Min told Scientific American.
The most water-repelling plastics, such as polyethylene and polypropylene, made more radicals than PET, New Scientist reported.
Martin Wagner, a toxicologist at the Norwegian University of Science and Technology who was not involved, called the findings exciting, Scientific American reported. "It implies microplastics themselves are a source of oxidative species," he said.
Other experts urged caution. Matthew Campen of the University of New Mexico called the work a "critical building block," New Scientist reported. But he added, "I encourage people to take a deep breath." When the researchers added a soap-like substance called a surfactant, fewer radicals formed, New Scientist reported. In the lungs, microplastics are quickly surrounded by such substances, Campen said.
It is still unclear how much this matters inside the human body, Min said. "How much plastic is in a regular human being?" he told New Scientist. "We have no idea right now."
What we know: In lab tests, common microplastics formed hydroxyl radicals where they met water, and the effect was weaker in blood serum.
What we don't: How much this happens inside the human body.
Where outlets agree New Scientist and Scientific American both report that the reactive molecules form where the plastic surface meets water.
Where they differ The outlets cited here report the same key facts so far.