Surprisingly, drinks in glass bottles can carry more microplastics than the same drinks in plastic, but the glass is not the problem: the painted metal cap is. A 2025 French government study found about 100 microplastic particles per liter in glass-bottled soft drinks, iced tea, and beer, five to 50 times more than in plastic bottles or cans. Bottled water and wine were the exceptions, staying low either way.
Key takeaways
– Glass itself does not shed plastic. The particles come from the plastic paint lining the metal caps.
– Soft drinks, iced tea, lemonade, and beer in glass showed the most; glass-bottled water and wine stayed low.
– Rinsing or wiping the cap before opening cut the particles by around 60 percent in testing.
What the study actually found
France’s food safety agency, ANSES, tested drinks in different containers and published the results in the Journal of Food Composition and Analysis (Chaib et al., 2025). Glass bottles of soda, lemonade, iced tea, and beer averaged roughly 100 microplastic particles per liter, far above plastic bottles and metal cans. Plain and sparkling water, though, stayed low in every container, from about 4.5 particles per liter in glass down to 1.6 in plastic, and wine was low too, even in capped glass bottles.
Why the cap, not the glass
The researchers matched the particles in the drink to the paint on the outside of the metal caps: same color, shape, and polymer. The caps are coated with a plastic-based paint, and as bottles are stored and transported, the caps rub against each other and develop tiny scratches that flake paint into the sealed drink. So the contamination tracks with the cap, which is why uncapped products like wine corked rather than capped, and water, came out lower.
Should you stop using glass bottles?
No. Glass is still one of the better choices for avoiding chemical leaching, and for water specifically it tested low. The takeaway is narrower: the painted metal cap is the weak point. It is also worth keeping perspective, since a group of scientists later published a comment noting the health significance of these particle counts is still uncertain (Food Packaging Forum, 2025). The finding is a useful surprise, not a reason to panic.
How to lower your exposure
Wipe or rinse the cap and the bottle rim before opening, which cut particle counts by about 60 percent in testing. Favor glass-bottled water and wine over capped glass sodas and iced teas if you are choosing. Best of all for daily drinking, use filtered tap water in a glass or stainless steel bottle, which avoids both the cap issue and the high counts found in plastic bottled water.
FAQ
Do glass bottles really have more microplastics than plastic?
For some drinks, yes. The ANSES study found glass-bottled sodas, iced tea, and beer had about five to 50 times more microplastics than plastic, traced to the painted metal caps. Glass-bottled water and wine stayed low, so it depends on the drink and the cap.
Where do the microplastics in glass bottles come from?
From the caps, not the glass. The metal caps are coated in plastic-based paint that scratches and flakes during storage and transport, dropping particles into the sealed drink. Researchers confirmed the particles matched the cap paint.
Is bottled water in glass safe from microplastics?
It is among the lower options. The study found glass-bottled water at about 4.5 particles per liter, low compared with the high counts in plastic bottled water. Wiping the cap first lowers it further.
How do I reduce microplastics from bottle caps?
Rinse or wipe the cap and bottle rim before opening, which reduced particles by around 60 percent in testing. Choosing corked or uncapped products and filtering your own tap water also avoid the issue.
Should I switch back to plastic bottles?
No. Plastic bottled water carries its own high microplastic counts plus chemical concerns. The better move is filtered tap water in a reusable glass or stainless steel bottle.
The bottom line
Glass is not the villain here, the painted cap is. Wipe the cap, prefer glass water and wine over capped sodas, and for everyday drinking switch to filtered tap in a reusable bottle, which sidesteps the whole problem.
