Glitter's sparkle hides a darker side—it can change the chemistry of our oceans (2025)

Glitter is festive and fun—a favorite for decorations, makeup and art projects. But while it may look harmless, beautiful even, glitter's sparkle hides a darker side. Those shimmering specks often end up far from party tables and greeting cards. You can even spot them glinting on beaches, washed in with the tide.

In our recent research, we discovered that glitter—specifically, the kind made from a common plastic polymer called polyethylene terephthalate (PET)—is not merely polluting the ocean. It could actively interfere with marine life as it forms shells and skeletons, which is a much bigger deal than it might sound.

Put simply: glitter helps the formation of crystals that nature did not plan for. And those crystals can break the glitter into even smaller pieces, making the pollution problem worse and more long-lasting.

We tend to think of microplastics as tiny beads from face scrubs or fibers from clothes, but glitter is in its own special category. It is often made of layered plastic film with metal coatings—the same stuff found in craft supplies, cosmetics, party decorations and clothing. It is shiny, colorful and durable—and extremely tiny. That makes it hard to clean up and easy for marine animals to eat, because it looks tasty.

However, our research paper in the journal Environmental Sciences Europe suggests that what really sets glitter apart from other microplastics is the way it behaves once it enters the ocean. It actively interacts with its surroundings; it's not drifting passively.

In our lab, we recreated seawater conditions and added glitter to the mix to explore whether glitter would affect how minerals—like the ones marine animals use to make their shells—form. What we saw was surprisingly fast and incredibly consistent: the glitter was kickstarting the formation of minerals such as calcite, aragonite and other types of calcium carbonates in a process known as "biomineralization."

These minerals are the building blocks that many marine creatures—including corals, sea urchins and mollusks—use to make their hard parts. If glitter is messing with that process, we could be looking at a serious threat to ocean life.

A crystal-growing machine

Under the microscope, we saw that glitter particles acted like little platforms for crystal growth. Minerals formed all over their surfaces, especially around cracks and edges. It was not a slow build-up—crystals appeared within minutes.

This can complicate natural processes. Marine creatures use very precise conditions to make their shells the right shape and strength. When something like glitter comes along and changes the rules—speeding up crystal growth, changing the types of crystals that form—it could mess with those natural processes. Like baking a cake and suddenly having the oven heat up to 1,000ºC, you might still get a cake—but it will not be the one you intended to cook.

Worse still, as the crystals grow, they push against the layers of glitter, causing it to crack, flake and break apart. That means the glitter ends up turning into even smaller pieces, known as nanoplastics, which are more easily absorbed by marine life and nearly impossible to remove from the environment.

Microplastics are eaten by marine life, from fish and turtles to oysters and plankton. This affects how animals feed, grow and survive. When we eat seafood, these microplastics become part of our own diet.

But our findings show that glitter does not just get eaten. It changes the chemistry of the ocean in tiny but important ways. By promoting the wrong kind of mineral growth, glitter might interfere with how ocean animals form their shells or skeletons in the first place.

This problem does not stop with wildlife. The ocean plays a key role in regulating Earth's climate, and mineral formation is part of that equation. If calcium carbonate formation in the ocean changes, it could also affect how carbon moves through the planet.

So, the next time you see glitter on a birthday card or in a makeup palette, remember this: it might look like harmless sparkle, but in the ocean, it behaves more like a flashy chemical troublemaker. What seems small and shiny to us could be a big, silent disruptor for the marine world.

And once it is out there, it is not going away.

This article is republished from The Conversation under a Creative Commons license. Read the original article.