Chemicals and harmful substances in bicycle and sports bottles - studies & alternatives

A recent study by the University of Copenhagen shows that numerous chemical substances are released into the drink when plastic bottles are used. Find out more about the study, its findings and possible alternatives here.

Underestimated danger: chemicals during sport
Our sense of smell and taste usually warns us of undesirable substances. But what about plastic bicycle bottles? Researchers at the University of Copenhagen have looked into this question and investigated whether chemicals from the bottles leach into the water.

In their study, they filled water into new, standard reusable sports bottles and left it to stand for 24 hours before analyzing it for chemical residues. The result raises many questions: over 400 different compounds were detected.

While BPA is now avoided in many bottles, it is now unknown substitutes that are causing concern. The researchers explain that the toxicity of around 70% of these substances has not yet been clarified . Photoinitiators, which are considered to be hormone-active and potentially carcinogenic, are particularly problematic. They also found plasticizers, antioxidants and release agents that are used in the production of plastics. Many of these substances could arise unintentionally through reactions with other chemicals.

Does the dishwasher help?
The assumption that a wash cycle effectively cleans the bottles is clearly refuted by the study. After a wash in the machine, the researchers found a total of 3,500 different chemical compounds - many of which were previously unknown. It is therefore strongly advised not to clean sports bottles in the dishwasher, as this can encourage the release of harmful substances.

Selina Tisler, postdoctoral researcher and first author of the study at the Department of Plant and Environmental Sciences at the University of Copenhagen, explains: "After rinsing, many chemicals from the bottle itself remain in the water. The most toxic substances that we identified only appeared after cleaning in the machine - presumably because washing attacks the plastic and promotes the release of the substances."

Microplastics in the brain:
New research results from Matthew Campen and his team at the University of New Mexico show that microplastics have been detected not only in organs such as the liver and kidneys, but also in particularly high concentrations in the brain. Plastic particles were found in all 52 corpses examined, in some cases in quantities equivalent to the weight of a small plastic spoon. This could also indicate a link between microplastics and the development of dementia.

The particles detected in the brain were mostly smaller than 0.2 micrometers and consisted mainly of polyethylene - a material used in many everyday objects. Due to their small size, they can cross the blood-brain barrier, although the health consequences are still unclear. It is also worrying that the amount of microplastics in tissue samples from 2024 was significantly higher than in samples from 2016.
This indicates that microplastics and nanoplastics are spreading rapidly in the environment.

20 times more microplastics from plastic bottles
According to the study, consuming water from plastic bottles can significantly increase the intake of microplastic particles - over 20 times more than when using tap water. According to an analysis of 21 studies, glass bottles also contain more plastic particles than tap water, possibly due to the filling process.

Heating food in plastic containers - especially in the microwave - also releases significant amounts of microplastics and nanoplastics. Even long-term storage at room temperature or in the refrigerator can lead to particles from the plastic being transferred into the food. The use of glass or stainless steel containers is therefore recommended as an effective measure to reduce plastic pollution.

What alternatives are there?
"We pay so much attention to low pesticide levels in our drinking water, but as soon as we fill it into a plastic bottle, hundreds or even thousands of substances are added. Even if we don't yet know exactly how these chemicals affect our health, I will prefer to use a glass or stainless steel bottle in future," - says Jan H. Christensen, Professor at the Department of Plant and Environmental Sciences at the University of Copenhagen.

However, glass and stainless steel bottles are often impractical for sports and cycling. They are heavier, cannot be crushed and pose a greater risk of injury in the event of a fall.

The start-up KEEGO offers an innovative solution:
Their bottle consists of several layers and has an interior made of pure titanium. This combines the advantages of a lightweight, flexible plastic bottle with the purity and neutral taste of a titanium bottle - without any unwanted chemicals.

Sources:

• University of Copenhagen: "Chemical leaching from reusable plastic bottles"

• University of New Mexico: "Microplastics accumulation in human brain tissue"

• Brain Medicine: "Human microplastic removal: what does the evidence tell us?"

• Nature Medicine: "Bioaccumulation of microplastics in decedent human brains."

• Science Advances: "Microplastics in the bloodstream can induce cerebral thrombosis by causing cell obstruction and lead to neurobehavioral abnormalities."

• Environmental Science & Technology: "Human Consumption of Microplastics."

• International Journal of Environmental Research and Public Health: "Occurrence of Microplastics in Tap and Bottled Water: Current Knowledge."

• Environmental Science & Technology: "Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea."

• Environmental Science & Technology: "Assessing the Release of Microplastics and Nanoplastics from Plastic Containers and Reusable Food Pouches: Implications for Human Health."