Turns Out the Cleanest Part of Your Glass Bottle Is the Glass

By Mark J Kaylor

Turns out choosing glass over plastic may not keep plastic out of your drink, at least not when the bottle wears a painted metal cap.

When France’s food safety agency tested water, sodas, lemonade, iced tea, beer and wine, the researchers expected glass to come out cleanest. It didn’t. Glass-bottled sodas, lemonades, iced teas and beers averaged around 100 microplastic particles per liter, roughly 5 to 50 times more than the same drinks in plastic bottles or cans.

The particles matched the paint on the outside of the caps in color, shape and type of plastic. Tiny scratches, likely from caps rubbing together in storage, seem to release flakes that end up in the drink. Water stayed low across the board: about 4.5 particles per liter in glass and 1.6 in plastic.

Two things belong alongside this. The study counted larger microplastics, not the far smaller nanoplastics that other research finds in plastic-bottled water in the hundreds of thousands per liter. And just cleaning the caps before bottling cut contamination by more than half.

So glass still earns its place on the shelf. The weak spot is the lid.

Turns out the cleanest part of your glass bottle is the glass.

References

1. Glass-bottled drinks carry more microplastics, traced to cap paint

Supports: particle counts by drink and container, cap-paint source, cap-cleaning reduction

Chaïb, I., et al. (2025). Microplastic contaminations in a set of beverages sold in France. Journal of Food Composition and Analysis, 107719.

https://doi.org/10.1016/j.jfca.2025.107719

2. Plastic-bottled water holds hundreds of thousands of nanoplastic particles per liter

Supports: the nanoplastic caveat

Qian, N., Gao, X., Lang, X., et al. (2024). Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Proceedings of the National Academy of Sciences, 121(3), e2300582121.

https://doi.org/10.1073/pnas.2300582121