From ocean depths to kitchen shelves, microplastics have infiltrated nearly every corner of the environment. They’ve been found in food, water, soil, air, household dust, and even human waste. This widespread presence raises serious concerns about its impact on both health and ecosystems.
To better understand the risks and inform public debate, the French food safety agency ANSES ran multiple studies to measure microplastic levels in everyday foods, especially seafood and beverages.
They checked drinks like water, soda, iced tea, wine, and beer to find out how many microplastic particles were in each. The study also looked at whether the type of bottle or cap, like glass vs. plastic, affected how much microplastic ends up in your drink.
Surprisingly, they found that drinks in glass bottles often contain more microplastic particles than those in plastic or metal containers. For example, drinks like cola, lemonade, iced tea, and beer stored in glass bottles contained around 100 microplastic particles per liter, an unexpectedly high number.
In comparison, the same beverages packaged in plastic bottles or cans had five to 50 times fewer microplastics, challenging the common belief that glass is the safer option.
Scientists at ANSES’s Boulogne-sur-Mer lab discovered a surprising source of microplastic contamination: the paint on metal bottle caps. They suspect flakes of paint may break off the lids and end up in drinks. Among the tested beverages, water and wine had fewer microplastic particles compared to others.
Water had few microplastic particles, no matter the packaging, about 4.5 per liter in glass bottles and 1.6 per liter in plastic bottles or cartons. Wine also had low levels when packaged in corked glass bottles.
Why microplastic levels vary between drinks remains unknown, except in one clear case: glass bottles with metal caps.
Researchers wanted to confirm how microplastics get into drinks stored in glass bottles and whether cleaning bottle caps could help. They studied three scenarios after first cleaning the bottles and filling them with filtered water: resealing the bottles with uncleaned caps, blowing air on the caps before sealing, or blowing air and rinsing the caps before sealing.
Researchers found that uncleaned caps released about 287 microplastic particles per liter into bottled water. Blowing air on the caps reduced this to 106 particles per liter. Blowing air and rinsing with water and alcohol, dropped it further to 87 particles per liter.
Key clues that the paint from bottle caps may be the source of contamination include a match between the color and composition of cap paint particles found in the drinks; tiny scratches on the caps, likely caused by friction during storage; and the release of flakes too small to see – indicating that the paint layer itself, rather than the bottle material, is a major source of microplastics.
"We were expecting the opposite result when we compared the level of microplastics in different drinks sold in France," said Iseline Chaïb, a PhD student in the Aquatic Food Safety Unit conducting the study. "In the absence of toxicological reference data, it is not possible to say whether the levels of microplastics found pose a health risk."
The researchers point out that their study has uncovered a source of microplastics that beverage producers are well placed to tackle.
Source: Anses
