Liquid polymers: Invisible plastic in everyday products

When we talk about plastic, many people think of packaging, bags or bottles. Less well known, but just as problematic, are liquid polymers. These synthetic plastics are not solid like plastic cups or films, but exist in dissolved or liquid form. They are found in cosmetics, detergents and care products - and end up in wastewater with every wash or shower.

What are liquid polymers?

Liquid polymers are plastics that are used as binders, coatings or consistency agents. Examples include acrylates, polyquaternium compounds and silicones. They are attractive to manufacturers because they make products creamier, create a protective film on skin and hair or stabilise pigments.

Invisible, but problematic

While microplastic particles are now more in the spotlight, liquid polymers often receive little attention. They have a similarly problematic behaviour in the environment:

• They are persistent, i.e. difficult to break down.
• They can accumulate in soil and water.
• Some enter sewage treatment plants via wastewater, but some pass through them unhindered and reach rivers and lakes.

This makes liquid polymers an "invisible contribution" to global plastic pollution.

How much liquid polymer ends up in wastewater?

In Germany, it is estimated that over 23,000 tonnes of poorly biodegradable organic polymers are discharged directly into the wastewater system every year through washing, cleaning and cleaning products. For cosmetic products, conservative estimates put the figure at around 23,700 tonnes, which also end up in wastewater after washing.

These liquid polymers are generally not biodegradable and often remain in sewage sludge. As around 40% of this sewage sludge is applied in agriculture or landscaping, residues of synthetic polymers can end up in the environment and represent an additional burden.

Effects on health and the environment

Research is still in its infancy, but there is growing evidence:

• Liquid polymers can be deposited on fish gills and plant surfaces and thus disrupt life processes.
• Some substances accumulate in organisms and enter the food chain.
• It is conceivable that they could also penetrate the human body via care products on damaged skin or mucous membranes.

Ubiquitous in everyday products

Typical applications are

• Creams and lotions (for smoothness and moisturising effect)
• Shampoos and conditioners (as a hair film or anti-frizz agent)
• Make-up and sun protection (for a smooth consistency or adhesion)
• Cleaning agents and detergents (as stabilisers or dirt carriers)

Regulation in Europe

While solid microplastic particles are already subject to stricter regulation and will be banned in many cosmetic products from 2025, liquid polymers are not yet subject to any comprehensive restrictions. However, the European Chemicals Agency (ECHA) is also increasingly analysing these substances in order to better assess their risks.

What consumers can do

• Look out for ingredients such as "acrylates", "polyquaternium" or "silicones" in the INCI list.
• If possible, choose natural cosmetics that do not use synthetic materials.
• Ask manufacturers specifically for polymer-free alternatives.

Conclusion

Liquid polymers are a hidden form of plastic that the public is barely aware of - and yet they can harm the environment and health. Precisely because they are invisible, many people underestimate their prevalence. A closer look at ingredients, stricter regulation and a reduction in everyday products are crucial to limiting this "invisible source of plastic".

Sources:

Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT (2020): Investigation of emissions of microplastics and liquid polymers from cosmetics and cleaning products in wastewater. Study commissioned by NABU. Berlin.

NABU study in cooperation with Fraunhofer UMSICHT, published via press portal, 2018 (updated data 2020). URL: https://www.presseportal.de/pm/6347/4079683