New Study Reveals: Glass Bottles May Release More Microplastics Than Plastic. Implications for Health and How to Mitigate Risks — in the Open Oil Market article.
French scientists from the National Agency for Food Safety (ANSES) conducted a series of tests on various beverages – water, soda, iced tea, beer, and wine – packaged in different types of containers. Their results surprised even the researchers themselves: significantly more microplastics were found in drinks from glass bottles compared to similar drinks in plastic bottles or aluminum cans. In some instances, the level of microplastic particles found in glass was five to fifty times higher. This raises questions about the long-held perception of the "purity" of glass packaging.
Unexpected Findings of the Study
The new research conducted by ANSES laboratory in France compared microplastic levels in popular beverages based on their packaging. In every tested category – whether it be carbonated soft drinks, iced tea, beer, or mineral water – glass bottles displayed the highest contamination with plastic particles. On average, approximately 100 microplastic particles were detected per liter of beverage from glass containers. In contrast, the same drink packaged in a plastic bottle or metal can contained only between 2 to 20 particles per liter. Even the researchers admitted they "expected the opposite result," initially assuming glass would be cleaner.
The Paint on Caps – A Hidden Source of Particles
The unexpectedly high contamination in glass bottles is linked to their caps. Glass beverage bottles are typically sealed with metal caps that have an internal plastic liner and are painted externally. The ANSES study found that the microplastic particles identified in the contents of glass bottles matched in color and composition with the paint covering these metal caps. In other words, the painted metal cap becomes a source of microplastic in the drink.
The cause of plastic entering the drink stems from the friction of the caps against each other during storage and transportation. Metal caps, in contact with each other prior to bottling, subtly scratch the painted surface. Tiny, invisible particles of the coating then flake off into the bottle during capping. Thus, each glass container with a painted cap contributes invisible contamination to the drink. In contrast, plastic bottles feature solid plastic caps without paint, which explains why their microplastic levels are substantially lower. Additionally, glass bottles with cork or other unpainted caps (like wine bottles) produce virtually no such effect.
Why Some Beverages Are More Contaminated
The differences in microplastic levels among beverage types prompted scientists to consider additional factors. For instance, why did soda and beer in glass contain dozens of particles, while water had only a few? Specialists suggest that the properties of the beverage itself and storage conditions may play a role:
- Carbonation and Pressure: Carbonated drinks (cola, lemonade, beer) create increased pressure within the bottle. This may intensify the friction of the cap against the neck and facilitate the flaking of paint particles.
- Acidity of the Medium: Some carbonated sodas and soft drinks have an acidic pH. Acid can soften polymer coatings, making it easier for microplastic particles to be released.
- Temperature and Transportation: Temperature fluctuations, shaking, and extended transportation increase wear on the caps. The movement of bottles in crates or containers leads to constant friction, which enhances paint flaking.
Thus, the highest levels of microplastic were found where vulnerable packaging elements (painted caps) combined with aggressive conditions – pressure from carbonation, chemical composition, and mechanical impacts during transport. Water and non-carbonated beverages, by contrast, proved less susceptible to this issue.
Potential Health Risks
It remains unclear whether the detected levels of microplastic pose an immediate threat to health – scientists have no established "toxicity threshold" for such particles. Nonetheless, the very presence of microplastics in food and drinks alarms medical professionals and environmentalists. Microplastics can accumulate in the body and affect it in various ways:
- Accumulation in Organs: Entering through food and drink, microplastics can settle in different tissues. Particle traces have already been found in the lungs, liver, intestines, and even in human blood and breast milk. Long-term accumulation of foreign particles poses risks of cellular and organ damage.
- Chronic Inflammation: The immune system recognizes plastics as foreign objects and attempts to combat them. The constant presence of microplastics may trigger low-grade inflammatory processes, which over time can damage healthy tissues.
- Disruption of Gut Microbiota: Plastic particles in the digestive system may disrupt the balance of gut bacteria. Studies indicate that microplastics alter microbiota composition, leading to digestive disorders, reduced immunity, and metabolic disruptions.
- Transport of Toxic Substances: Microplastics attract and adsorb various toxic compounds on their surface – from pesticides and heavy metals to dioxins. When these chemicals enter the body along with the particles, they can cause additional harmful effects, including hormonal disruptions.
Although direct harm from small doses of microplastic has yet to be conclusively proven, medical experts agree that excess "plastic dust" in our diets certainly does not promote health. Particularly concerning is its ability to provoke chronic inflammation and carry harmful chemicals into the body – factors that may contribute to the development of serious diseases over time.
Ways to Reduce Microplastics in Packaging
Fortunately, having identified the source of contamination, researchers are also proposing solutions to reduce it. Beverage producers can relatively easily cut down on plastic from caps by improving technological processes. ANSES experts tested several methods for treating caps before capping and achieved a significant reduction in microplastics. Key measures include:
- Pre-Cleaning Caps. Blowing new caps with compressed air, followed by rinsing with filtered water and alcohol before bottling, reduced microplastic content by approximately 60%.
- Gentle Storage of Caps. It's crucial to minimize friction among caps before bottling. Producers can change the storage and transportation conditions of caps – for instance, using pads or dividers to prevent mass contact among caps. Reducing mechanical wear on the coating will lessen the formation of scratches and paint debris.
- Improving Materials and Coatings. Another direction is to develop more wear-resistant cap materials. Using paints that are less prone to flaking or alternative protective coatings can minimize particle migration.
Implementing these measures can significantly improve the situation. Adapting processes (cleaning or new storage conditions) is relatively inexpensive for manufacturers, and the effect for consumers is a cleaner product without excessive impurities.
Implications for the Beverage Industry
The findings from French specialists serve as a signal for the entire beverage and packaging industry. Glass containers have long been promoted as an eco-friendly alternative to plastic: they do not create plastic waste, are recyclable, and do not release harmful substances into their contents. However, the new factor of microplastics shows that glass also has hidden risks. This does not mean that we should abandon glass bottles; rather, improvements to their design and production cycle are necessary.
For beverage manufacturers, the takeaway is clear: quality control must consider not only the liquid itself but also all packaging elements. Additional checks for microplastics and preventive measures (such as the described cap cleaning) could become the new standard in the industry. Regulators and consumers are increasingly focused on the safety and purity of products. Companies investing in "microplastic-free" solutions will gain a competitive advantage in reputation.
What This Means for Consumers
Being aware of this issue enables consumers to make more informed choices. While fully avoiding microplastics in modern conditions is challenging, people have the right to expect transparency and technological improvements from brands. Simple actions – such as rinsing the neck and cap before resealing a bottle – can slightly reduce plastic contamination in the drink. Ultimately, heightened awareness of microplastics among all market participants stimulates the creation of cleaner and safer products for consumers.
