Since the 1950s, plastic production has soared, and single-use plastics have driven pollution in both terrestrial and aquatic environments. As they degrade, they form micro- and nano-plastics that permeate every ecosystem — from 10,000 m beneath the ocean surface to Himalayan glaciers and even clouds.

A French national study by the MICROSOF project — led by National Research Institute for Agriculture, Food and Environment and Institute for Research in Materials — found MPs in 75% of soil samples across 33 sites. The findings highlight the widespread presence of MP pollution in French soils and its potential risks to ecosystems and agriculture.

Health Risks

Although quantifying MPs in the environment and human samples is challenging, micro- and nano-plastics can penetrate organs of exposure, such as the lungs, colon, and skin, and reach distant organs, such as the testes, placenta, kidneys, and brain.

A report by the Parliamentary Office for Scientific and Technological Assessment highlights that microplastics have been detected in human brain tissue, reaching levels as high as 0.5% by weight. Moreover, the number of MPs in the lungs increases with age, suggesting long-term persistence in the body. Data indicate that MP exposure may increase the risk for conditions such as stomach cancer, myocardial infarction, and stroke. Their toxicity is also linked to the chemical substances they contain or can absorb from the environment; over 4000 are classified as hazardous to human health.

Contamination Levels

Humans primarily ingest MPs through contaminated food and drinks. Numerous studies have noted the presence of MPs in bottled and tap water and in certain foods, such as vegetables, fruits, meat, eggs, tea, and rice.

ANSES researchers recently measured MP counts in bottled water, soft drinks, iced teas, lemonades, beers, and wines. They detected MPs measuring 30 μm to 500 μm in every beverage, with levels varying by beverage type.

Bottled water showed relatively low concentrations (2.9 MPs/L compared to the results already published in the literature. Sodas and lemonades registered 31.4 MPs/L and 101.5MPs/L, respectively; iced teas, 14.6 MPs/L; and beer, 84 MPs/L, with no notable difference between the varied brands evaluated. Wine in glass bottles averaged 12.0 MPs/L, although other studies have reported higher levels. The authors caution that comparing studies is challenging given the variations in standards, the variability in the size of the particles considered, the samples, and the volumes taken.

Glass Bottles 

Beverages in glass bottles contained higher levels of MPs than those in plastic bottles or cans. The MPs matched the color and polymer composition of the cap materials, suggesting that cap abrasion during large-scale storage drives contamination. Washing caps before sealing can significantly reduce MP levels. Within the glass bottle category, only wine stands out because of the use of cork stoppers.

Microplastics are present in all environments and have even been detected in humans. As a result, more and more worldwide studies are focusing on the contamination of food and beverages by microplastics. To date, none of these studies has examined the contamination levels in beverages sold in France. The current study was set up to address this gap and investigate the level of microplastic contamination in water, soft drinks, beer and wine. This study does not aim to provide an exhaustive overview of all the drinks sold in France. However, efforts were made to study the impact of different containers: plastic, glass, brick, can, cubitainer, on this contamination. Heterogeneous results were obtained with mean contamination levels of 2.9 ± 0.7 MPs/L in waters, 31.4 ± 16 MPs/L in colas, 28.5 ± 13.1 MPs/L in teas, 45.2 ± 21.4 MPs/L in lemonades, 82.9 ± 13.9 MPs/L in beers and 8.2 ± 3.3 MPs/L in wines. It was observed that the most contaminated containers were glass bottles. Caps were suspected to be the main source of contamination, as the majority of particles isolated in beverages were identical to the color of caps and shared the composition of the outer paint.

Introduction

Initially considered as a revolutionary material, plastic production has steadily increased over the years. Excluding fibers, it has grown from 1.5 million tons in the 1950s to 400.3 million tons in 2022 (PlasticsEurope, 2023). Because of their high strength, low cost, low weight, and ease of use, plastics are used worldwide. More specifically, packaging made of polyethylene (PE) (high-density HDPE and low-density LDPE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS) accounts for about 44 % of the volume produced on the global market (PlasticsEurope, 2022).

However, the increased manufacture of single-use plastics has also led to a rise in garbage found in terrestrial and aquatic habitats due to inefficient waste management. The 1970s marked the beginning of research into the existence of plastic debris in marine environments (Carpenter et al., 1972). The accumulation of plastics has been widely documented as a significant environment and human health concern.

The degradation of these plastics represents one threat, as fragmentation releases micro- or nanoplastics (Alimba and Faggio, 2019). Microplastics (MPs), defined in the current study as particles smaller than five millimeters (Arthur et al., 2009a), are present in all ecosystems. Their small size allows humans exposure through inhalation, ingestion, or skin penetration (Sun and Wang, 2023), with ingestion being the main route of human due to their presence in foods and beverages (Prata et al., 2020). Numerous studies have evaluated the degree of contamination of edible organisms, including bivalves, crustaceans, and different types of fish, due to the absorption of MPs by aquatic organisms (Rubio-Armendáriz et al., 2022).

Glass contamination

With the exception of wine, the MPs content of glass versus plastic bottles was significantly higher for all beverages (water, cola, tea, lemonade, and beer). Previous research on beverages has shown that various types, including soft drinks, beer, wine, and drinking water, tend to exhibit higher levels of contamination when stored in glass containers (Basaran et al., 2024, Lam et al., 2024, Li et al., 2023, Schymanski et al., 2018, Wang and Wang, 2024). However, other articles indicated that glass contained less MPs than plastic (Kankanige and Babel, 2020). This variability in results across studies can be attributed to differences in sampling between countries. However, no study has established a link between the contamination of glass bottles and the paint used on caps.

In this study, the MPs found in the glass bottles corresponded to the color and polymeric composition of the paint on the caps, which are coated with alkyd thermosetting resin or PES/PET-based paint.

In addition, encapsulation experiments with new caps and clean bottles filled with water revealed the presence of MP identical to the cap paint in the water. These results demonstrated that cap paint was a source of MP contamination in bottles. Pre-cleaning of new capsules, by blowing them out and rinsing them with water/ethanol/water, has significantly reduced the number of MPs per encapsulated bottle, lowering it by approximately three, compared to untreated capsules. Furthermore, the high concentration of MPs found in the rinse water from these capsules supported the hypothesis that pre-cleaning removed MPs that would have ended up in the liquid. Cleaning seems to be essential and could significantly minimize contamination of the liquid in the bottle by paint particles present in the capsule.

Actually, the obtained results indicated that one of the main sources of the contamination was the capsule, probably due to its storage before capping. It is likely that capsules are stored in large quantities packaging, increasing the possibility of abrasion and surface friction when capsules collide. This theory was supported by the discovery of scratches on their surface and pieces of capsules of the same color adsorbed inside of them.

The contamination from the paint on the outside of the capsule raises a significant concern, as in addition to the level of microplastic contamination, additives may be present.