Glass Bottles May Contain Up to 50 Times More Microplastics, Study Finds

The evidence showing the harmful effects of microplastics is building up. Study after study shows that microplastics are appearing in our land, food, and even in our brains. While research on how microplastics affect human health is still developing, there is evidence to suggest they negatively affect our gut, liver, and possibly even our DNA. But if you've switched to glass to avoid microplastics, you might want to reconsider.  

In late June, France's food safety agency released the findings of a surprising study, which showed that drinks sold in glass bottles contain more microplastics than those in plastic bottles. 

Guillaume Duflos, research director at the French food safety agency, explained to AFP that the researchers aimed to “investigate the quantity of microplastics in different types of drinks sold in France and examine the impact different containers can have.”

Their work examined the “impact of different containers,” including plastic, glass, brick, can, cubitainer, and included water, tea, lemonade, soda, beer, and wine. And while it found microplastics in all the containers studied, the team concluded that “Counterintuitively, drinks sold in glass bottles were more contaminated by [microplastics].”

But how?

“Experiments have shown that these [microplastics] originate from the exterior paint of capsules,” the team wrote, indicating that the plastics are likely coming from the plastic caps on top of the bottle. They added that “a cleaning step before encapsulation can significantly reduce beverage contaminations. However, cleaning does not remove all the [microplastics] from the capsule.”

“We expected the opposite result,” Iseline Chaib, a PhD student who conducted the research, additionally shared with AFP. “We then noticed that in the glass, the particles emerging from the samples were the same shape, color, and polymer composition — so, therefore, the same plastic — as the paint on the outside of the caps that seal the glass bottles.”

And it wasn't by a small margin. The study found that glass bottles of soda, iced tea, beer, and lemonade contained about 100 microplastic particles per liter, which Phys.org explained is up to 50 times higher than the number detected in plastic or cans. 

These findings shouldn't surprise regular readers of Food & Wine. As we previously reported, a 2024 study found that the more you open and close a soda bottle, the more microplastics are introduced to the drink through the cap. The researchers discovered that with each additional opening, microplastic levels rose, reaching 46 particles for Coca-Cola by the 20th opening and 62 for Schweppes.

There was, however, some good news in this latest study. The team found that water contained fewer microplastics, as did wine, even in glass bottles. The researchers couldn't determine why.