Drinks in glass bottles contained more microplastics than those in plastic bottles or cans, according to a new French study.
Researchers traced most of the microplastic particles to the painted metal caps used to seal glass bottles.
Simple changes in bottle cap handling—like rinsing or air-blowing—reduced microplastic levels by up to 60%.
You might think glass bottles are the safest way to enjoy your favorite drinks—but a new French study suggests otherwise.
Researchers from ANSES (France’s national food safety agency) discovered that, surprisingly, beverages in glass bottles can contain more microplastic particles than those in plastic containers or cans.
Let’s unpack what that means for your next sip.
The study
Here's how they did it:
What they tested: In June 2023, the team purchased six samples of each beverage type—water, soft drinks, lemonade, iced tea, beer, and wine—from local retailers in France. All samples came from the same production batch per drink type.
Goal: To find out how many microplastic particles are hiding in common drinks and whether the container (glass, plastic, or can) makes a difference.
Surprise finding: Glass bottles led in microplastics—averaging around 100 particles per liter, compared to much lower levels in plastic bottles and cans.
But where were these plastics coming from?
The researchers pinpointed the culprit: paint on the metal caps of glass bottles. Tiny scratches—likely from friction during storage—shedded plastic particles into the drinks.
What can brands do?
The researchers tested simple fixes: rinsing caps with water and alcohol, or air-blowing them, which cut particle levels by 60%.
So yes, companies can reduce microplastic contamination with better cap-handling practices.
Should You Worry?
There’s no evidence yet that these levels harm your health. This study simply shines a light on an unexpected source of microplastics in everyday drinks. If you love glass bottles, it's not that you need to ditch them—but maybe look out for drinks with untreated, paint-free caps or packaging innovations tackling this issue.
In short: the bottle might not be the problem, but the cap could be. And that’s a detail worth knowing before your next refill!