Glass bottles, long considered the environmentally-friendly alternative to plastic, are contaminating beverages with up to 50 times more microplastics than their plastic counterparts, according to a shocking new study from French researchers.
Key Takeaways
- French food safety agency ANSES found glass-bottled beverages contain 5-50 times more microplastic particles than drinks in plastic bottles or metal cans
- Bottle cap paint was identified as the primary source of contamination, with microplastics matching the color and composition of the caps
- Beer showed the highest contamination levels, while wine and water had significantly lower microplastic presence
- Rinsing bottle caps with water and alcohol can reduce microplastic contamination by up to 60%
- Health impacts remain uncertain, though microplastics have been found in human tissues including the brain
Unexpected Findings Challenge Environmental Assumptions
The comprehensive study, published in the Journal of Food Composition and Analysis by France’s food safety agency ANSES, has turned conventional wisdom about packaging safety upside down. Researchers found glass bottles of cola, lemonade, iced tea, and beer contained substantially more microplastic fragments than plastic bottles or metal cans. Glass containers averaged around 100 microplastic particles per liter, with some beverages showing up to 50 times more contamination than their plastic-bottled equivalents.
“We were expecting the opposite result when we compared the level of microplastics in different drinks sold in France,” said Iseline Chaïb, one of the researchers involved in the study.
The investigation aimed to assess microplastic contamination in beverages and determine how container types impact pollution levels. Researchers analyzed various drinks sold in France, examining microplastic concentrations and identifying potential contamination sources. Beer showed the highest contamination levels, followed by lemonade and soft drinks, while water and wine had substantially lower microplastic presence, even when packaged in glass.
Glass bottles found to have five to 50 times as many microplastics as plastic bottles in shocking new study https://t.co/het6HQMnsF pic.twitter.com/NrbyGivG7h
— New York Post (@nypost) June 22, 2025
Bottle Caps Identified as Primary Culprit
After careful analysis, researchers pinpointed painted bottle caps as the main source of contamination. The microplastics found in beverages matched the color and composition of the paint on the outside of caps that seal glass bottles. Microscopic examination revealed tiny scratches on the cap paint, likely created by friction during handling, which released microplastic particles into the beverages. This discovery explains why glass bottles, despite their solid structure, introduced more contaminants than plastic containers.
“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,” explained Iseline Chaib, researcher with ANSES.
Simple Solutions and Lingering Questions
Fortunately, the researchers discovered that simple cleaning methods can significantly reduce contamination. Blowing air and rinsing caps with water and alcohol can decrease microplastic pollution by up to 60%. This straightforward approach offers consumers an immediate way to reduce their exposure while manufacturers potentially work on longer-term solutions. The simplicity of this fix stands in stark contrast to the complexity of the global microplastic problem, which has seen these tiny particles detected worldwide in air, food, and human bodies.
“The reason for this discrepancy remains to be explained,” said Guillaume Duflos, a researcher involved in the study, referring to the varying contamination levels across different beverages and the surprisingly low microplastic presence in wine bottles.
While the health implications of microplastic ingestion remain uncertain due to limited toxicological reference data, previous research has detected microplastics in human tissues, including the brain. Some studies have linked microplastic exposure to inflammation and hormone disruption, raising concerns about long-term health effects. The ANSES researchers didn’t assess specific health risks in this study but emphasized the importance of reducing exposure through simple preventative measures.
Rethinking Sustainable Packaging
These findings challenge the common assumption that glass is inherently cleaner than plastic for food and beverage packaging. For decades, environmentally-conscious consumers have chosen glass over plastic, believing it to be safer for both human health and the environment. This study suggests the reality is more nuanced, with different packaging materials presenting distinct advantages and disadvantages. Manufacturers may need to reconsider bottle cap designs and materials to address this newly identified contamination source.
The research underscores how environmental science continually evolves, sometimes producing counter-intuitive results that force us to reassess conventional wisdom. While glass remains recyclable and doesn’t break down into environmental microplastics like plastic bottles, this study highlights that no packaging solution is perfect. Consumers now face more complex decisions when selecting products based on environmental and health considerations, with traditional assumptions about packaging safety requiring reevaluation.
